A small, soft tumor in a dog. Tumors in dogs: types, symptoms and treatment

There are benign and malignant tumors.

Benign tumors have what is called expansive growth. It is characterized by the fact that normal tissue surrounding the tumor is compressed and pushed back (or pulled apart). Due to this, clear boundaries appear between the tumor and surrounding tissues and a capsule is formed, within which the tumor grows. The histological structure of benign tumors is similar to the structure of the original tissue.

Malignant tumors grow by penetrating (infiltrating) into surrounding tissues and destroying them. They usually do not have a capsule, but in dogs some, such as malignant mammary tumors, grow in a capsule. Malignant tumors are characterized by the ability to metastasize, that is, to spread throughout the body: tumor cells are carried through the bloodstream or, more often, lymphatic tracts to internal organs, where they give rise to the development of new (secondary) tumor nodes. Histologically, in malignant tumors, the differentiation of cellular elements is reduced and signs of similarity with the original tissue are lost.

With some experience and skill, one can presumably judge whether a tumor is benign or malignant; however, a definitive diagnosis can only be made on the basis of its microscopic examination. The simplest method is puncture of the tumor followed by examination of the punctate under a microscope.

Technique of puncture biopsy: a sterile needle is inserted into the depth of the tumor, placed on a syringe with a capacity of 20 cm 3, in which the piston is pushed in all the way. By repeatedly sharply pulling the piston upward, cellular material is drawn into the needle and then, using the piston, it is squeezed onto a glass slide. Usually this is a mucous liquid, which is smeared onto glass with the same needle, dried for 20-30 minutes and stained according to Leishman-Romanovsky. Using puncture, it is possible to fairly correctly determine the histological type of the tumor being studied. If a more accurate diagnosis is required, they resort to an incisional biopsy: the skin, subcutaneous tissue, surrounding tissues and capsule are dissected, a piece of tumor measuring 1´ 1 cm 3 is taken, subjected to special processing accepted in histological laboratories, and the biopsy sample is examined under a microscope.

In dogs, tumors account for 8-18% of the total number of diseases. They develop, as a rule, in the second half of life, on average at 7-9 years of age and older; in isolated cases they are up to 3-5 years of age and very rarely - up to 1-2 years.

Tumors occur approximately equally often in both females and males, with the exception of tumors of the mammary glands, which affect females and extremely rarely males.

There is evidence that certain breeds of dogs are predisposed to certain types of tumors. Thus, Scottish terriers are prone to tumors of the skin, English cocker spaniels - of the oral mucosa, fox terriers - of the perianal glands. Boxers are especially prone to tumors: they are more likely than dogs of other breeds to have tumor diseases of the blood, skin, etc. Dogs of large breeds (St. Bernards, Newfoundlands, Great Danes, etc.) often have bone tumors.

Tumors can be divided into two groups: external localization and internal organs. Much more is known about the former than about the latter, since they attract the attention of dog owners earlier and force them to go to veterinary clinics.

The principles of clinical classification of tumors have been developed, which allow unifying the assessment of the stage of the disease. The classification is accepted in most foreign veterinary clinics. Its goal is to create a unified system of signs that makes it possible to determine the spread of a tumor both within the affected organ and in areas of regional and distant metastasis.

Under the stage of the tumor process is meant a stage in the development of a tumor disease, expressed as the sum of certain clinical symptoms. The stage of the disease is determined on the basis of such clinical data as the size of the tumor, the degree of damage to the original organ, the degree of transition of the tumor to neighboring organs or surrounding tissues, the presence or absence of metastases. Based on these indicators, stage I means the restriction of tumor growth to the surface tissues of the original organ, small (up to 3 cm) size of the tumor node, and the absence of metastases. Stage II is characterized by large tumor sizes (up to 5-6 cm), its germination into deeper tissues of the original organ, but the tumor remains mobile (displaces relative to surrounding tissues), and there may be single small metastases in regional lymph nodes. At stage III, the tumor is significant in size (more than 5-6 cm), its mobility is limited due to germination into surrounding tissues and beyond the organ, and there are large metastases to regional lymph nodes. Stage IV is the spread of the tumor far beyond the affected organ and the presence of distant metastases to the liver, kidneys, lungs, i.e., in fact, damage to the entire body.

In 1974, a WHO expert committee developed the TNM classification of tumors for domestic animals, particularly dogs. This classification is based on three components:

T - primary tumor (tumores);

N - lymph nodes (noduli);

M - metastases (metastasis).

Each of the elements of this system has several gradations that characterize the degree of spread of the malignant tumor. Depending on the size of the tumor and its growth into the organ or surrounding tissues, T 1, T 2, T 3, T 4 are distinguished. Depending on the damage to the regional lymph nodes, N 0 (no metastases), N 1, N 2, N 3 are distinguished (respectively, suspicion of metastases, multiple mobile, immobile metastases). The symbol M characterizes the absence (M 0) or presence of distant hematogenous metastases (M 1). For example, T 3 N 2 M 0 means that there is a tumor larger than 5 cm with invasion into surrounding tissues, multiple metastases to regional lymph nodes, and there is no reliable data on the presence of distant metastases.

The TNM classification is, in essence, an improved 4-stage classification, in which stage I corresponds to T 1 N 0 M 0 , stage II corresponds to T 2 N 1 M 0 , stage III corresponds to T 1 N 2 M 0 , stage IV corresponds to T 1 N 3 M 1. The advantage of the classification is that it, in a concise form using symbols, provides a fairly clear and complete expression of the clinical stage in which the animal with a tumor is at the time of examination. The classification was created to ensure that veterinarians apply uniform principles and uniform terminology for assessing the stage of the tumor process.

Tumors of the mammary glands in dogs they account for more than half of all tumors. They are usually found in dogs older than 6-7 years and do not occur under the age of 4 years.

The appearance of a breast tumor is preceded by long-term hormonal disorders: an increase in the level of estrogen in the body. It is known that castration of females before the first heat reduces the likelihood of developing mammary tumors by 50 times. An important contributing factor is false pregnancy, which is common in dogs in the second half of life, as well as the lack of mating and natural feeding of puppies. It is obvious that the normal functioning of the mammary glands is a factor that prevents the development of tumor growth.

In the mammary glands of females, tumors occur with unequal frequency: in the 1st and 2nd pairs of glands they are rare, in the 3rd pair they are more common, and mainly affect the 4th and 5th pairs. The incidence of tumor growth depends on the functional activity and volume of mammary gland tissue. For example, in the 5th pair of mammary glands, which have the most pronounced functional activity, tumors occur 8-10 times more often than in the 1st pair, in which the volume of glandular tissue and its ability to lactation are very small.

Due to the superficial (subcutaneous) location of tumors in the mammary glands, their intravital diagnosis is not difficult. The formed tumor is a round, lumpy formation of elastic or dense consistency. Tumors are, as a rule, single, although multiple neoplasms are often observed, with one tumor node appearing first, and then others. Therefore, when speaking about multiple tumors of the mammary glands, we should mean only different stages of the same process, which is of no small importance when determining the size of surgical intervention.

The onset of tumor growth in the mammary gland is usually associated with estrus or false whelping; a small nodule with a soft, doughy consistency begins to be felt in the gland tissue. Sometimes the nodules are multiple in nature, which upon palpation creates the sensation of a “bag of shot.” Such changes are not yet a tumor, and they should be classified as mastopathy, that is, a pathological condition that is a pretumor, but can later turn into a tumor. Animals with mastopathy are subject to observation, since after a certain time one appears among the small nodules, which continues to increase in size and acquires a denser consistency. For a long time, the tumor nodule may not change its size or grow slowly, but after another estrus or false pregnancy it grows noticeably, becoming dense and lumpy (stage I). If palpation reveals a slight increase in regional lymph nodes, this means that the process has entered stage II. Further growth of the tumor is associated with its germination into the surrounding tissues, as a result of which it becomes immobile. The skin covering the tumor often loses hair and becomes tense, hyperemic, and hot to the touch. If the tumor is located in the 4th-5th pair of mammary glands, its surface facing the inner surface of the hind limbs becomes ulcerated as a result of constant trauma when the dog moves. However, ulcers, sometimes multiple, can also occur in those parts of the tumor that do not come into contact with the inner surface of the hind limbs. Their appearance can be explained by necrosis and suppuration of individual areas of the tumor. Multiple large metastases are detected in regional lymph nodes (stage III).

At the same time, very often there are tumors that grow in the form of a rounded dense formation, reach sizes of up to 10-15 cm or more, while maintaining mobility in relation to the underlying tissues. Metastases in regional lymph nodes are not detected, although the tumor is malignant, has a complex (mixed) structure with excess mesenchymal tissue up to the formation of a bone component.

A special group consists of tumors of the mammary glands that grow without a capsule and early invade the aponeurosis, rectus abdominal wall muscles and skin. In such cases, an extensive ulcerative surface with deep fistulous tracts and purulent-necrotic discharge is found. This form of tumors, called armored, is characterized by invasive tumor growth with spread through the lymphatic tract towards the regional lymph nodes, which together with the tumor form a single immobile complex.

The dog's progressive loss of body weight and appetite, increased thirst, obvious weakness and apathy, and cough indicate metastatic damage to the lungs and other internal organs (stage IV). Metastases in the lungs are clearly visible on chest x-ray, which is performed in a direct or lateral projection. Metastases in other internal organs are not determined by radiography.

Metastasis is a natural stage in the development of a tumor disease if the primary breast tumor has not been surgically removed. Due to the anatomical features of the dog’s body, lymph flow from the five pairs of mammary glands has different directions: from the 1st, 2nd, 3rd pairs of glands, lymph flows into the axillary lymph nodes, where metastases should be looked for when examining an animal with a tumor of this localization. From the 4th and 5th pairs of mammary glands, lymph enters the inguinal lymph nodes, where the first metastases appear. Due to the fact that the left and right chains of the mammary glands have separate lymph and blood circulation, metastases to the lymph nodes are always found on the side where the tumor is located.

Metastatic spread of a tumor is one of the signs of its malignancy, however, a final judgment about the nature of the tumor can only be given by a histological study of the removed tumor. The clinical behavior of a breast tumor is largely determined by its histological type, since even malignant tumors have different growth rates and unequal ability to metastasize. Differentiated (mature) tumors have the structure of so-called papillary or tubular cancers of the simple type, which have a moderate degree of malignancy and a low ability to metastasize.

Mammary cancer in dogs often has a very peculiar complex structure, when papillary or tubular structures are combined with neoplastic proliferation of so-called myoepithelial cells; in this case, the mammary tumor takes on a more benign clinical course, although it itself is malignant.

Canine mammary tumors are treated surgically. In this case, it is necessary to take into account the age of the animal, the presence of concomitant diseases of the heart, liver, kidneys, as well as the extent of the tumor, i.e. the clinical stage. A prerequisite for surgery for malignant tumors is adherence to the principles of oncological radicalism, which involves excision of the organ or tissue from which the tumor originates, within a wide range, including the surrounding healthy tissue.

Performing an oncological operation requires knowledge of the characteristics of tumor spread within the affected organ, transition to neighboring organs and tissues, and a clear understanding of the routes of metastasis through the lymphatic tract. High efficiency of long-term results is achieved if the principles of ablastics are followed, which involves preventing the surgeon from spreading tumor cells during surgery.

The operation to remove a breast tumor is performed in several stages:

1. If the tumor is localized in the 5th-4th pair, at least 3 cm away from the edge of the tumor, the skin is dissected with two bordering semi-oval incisions and separated to the side.

2. The anatomical boundaries of the tumor are exposed, the fatty tissue is dissected to the aponeurosis.

3. Vessels supplying the tumor are ligated with catgut in the cranial and caudal parts of the surgical wound, departing from the visible boundaries of the tumor by 3-5 cm.

4. Bluntly, a block of tissues is dissected together with fatty tissue and a tumor from the aponeurosis, exposing the feeding vascular pedicle. Allocate superficial inguinal lymph nodes.

5. The vascular pedicle is carefully stitched with silk and crossed. The surgical wound is sutured in layers and tightly, and rubber drainage is left in its caudal part for one day.

6. When removing a tumor located in the first three pairs of mammary glands, the fringing incision of the skin and fatty tissue is continued to the armpit and the tumor and lymph nodes are isolated in a single block, followed by layer-by-layer suturing of tissues and skin. Drainage in this case is inserted into the cranial end of the wound.

A contraindication to surgical treatment is generalization of the tumor process, i.e. tumor dissemination and the appearance of distant metastases.

Surgical treatment is most effective in the presence of the following conditions:

1. The tumor does not spread to surrounding tissues (stages I-II). When the tumor spreads to surrounding tissues and develops metastases to regional lymph nodes (stage III), the surgical method is also applicable, but long-term results in such cases are worse.

2. The boundaries of the tumor and its visible demarcation from surrounding tissues are clear. Their absence reduces the possibility of radical tumor removal.

3. The rate of tumor growth is a factor that determines the effectiveness of surgery in terms of prognosis. With a long development of the process, it is possible that the malignant tumor is mature and the favorable outcome in this case is much higher.

When it is known that radical removal of a tumor is impossible, sometimes they resort to so-called palliative surgery: a large disintegrating or bleeding tumor is removed in order to subsequently treat the remainder of the tumor or its metastases with radiation or antitumor drugs. However, this is only possible in specialized institutions.

Removing a breast tumor in clinical stages I-II does not present any difficulties. The outcome and prognosis are favorable. The volume of surgery for stage III is much larger; wide excision of the tumor, surrounding tissues, including the aponeurosis, sometimes part of the rectus abdominal wall muscles and a package of lymph nodes is required. The outcome and prognosis are not always favorable; relapses and distant metastases are possible. However, the life expectancy of dogs operated on for tubular or papillary mammary cancer of the simple type is on average 12-16 months, and for tubular or papillary cancer of the complex type - 16-36 months.

If an animal has several tumors of the mammary glands, then first the tumor node that is the largest and represents the main danger to the animal is removed. In the future, after the sutures are removed and after the animal has fully recovered from the surgery, the issue of the need to remove other mammary tumors is decided.

Tumors of the skin and subcutaneous tissue can occur in any part of the body; they are rounded formations that rise above the surface of the skin. Often there is a need to differentiate them from formations of a non-tumor nature: cysts (dermoid), which grow slowly and contain a thick liquid inside; retention cysts that develop as a result of blockage of the output ducts of the skin glands, such as sebaceous.

Papillomatosis of the skin and oral mucosa is a tumor-like disease and is a multiple rash in the form of small formations on thin legs. For the treatment of papillomatosis, intravenous administration of 0.5% novocaine can be recommended.

A benign tumor of the skin and subcutaneous tissue has a rounded shape and elastic texture, the coat over the tumor is not changed.

A malignant tumor of the skin is most often a flattened formation that grows mainly in breadth and retains mobility in relation to the underlying tissues for a long time. There is no coat over the tumor, the surface is bumpy, often bleeds, covered with fibrinous-necrotic overlays. Metastases to regional lymph nodes occur relatively late. This type of tumor is most often squamous cell carcinoma.

Treatment of tumors of the skin and subcutaneous tissue is their surgical removal.

Malignant tumors of the skin require a wide excision with the capture of surrounding tissues and regional lymph nodes, if they are enlarged due to metastatic lesions. If the tumor is located on the extremities, where the supply of skin is limited, then after excision of the tumor, a defect occurs that requires plastic replacement. To do this, on any area of ​​the skin where there is a sufficient supply of it, an area corresponding in size to the defect is marked and cut out, and it is sewn, aligning the edges of the flap and the skin defect. In more complex cases, they resort to the formation of a skin stalk according to Filatov.

Pigment-containing tumors - melanomas - occur in the skin or mucous membrane of the oral cavity in the form of a rounded dark-colored node. When localized in the skin, the tumor grows slowly, retains mobility and has a relatively benign clinical course, metastasizes late. Surgical removal of the tumor is not difficult. When localized on the mucous membrane of the mouth, melanoma quickly grows into the surrounding tissues, becomes immobile and early metastasizes to the cervical lymph nodes. The tumor is prone to bleeding due to constant trauma to its teeth and food. Surgical removal of such a tumor is not always possible even for an experienced specialist.

Mast cell tumors (mastocytomas), which are solitary rounded intradermal formations, constitute a special group. There is no fur over the tumor. It occurs more often on the lateral surfaces of the trunk and limbs and occurs, as a rule, in boxers. During surgical removal, it persistently recurs, and new nodes appear near the removed one. The tumor is resistant to both drug treatment and radiation.

Tumors of the perianal (near-anal) glands quite common in dogs, and it is characteristic that they occur only in males. Diagnosis of neoplasms is not difficult due to their typical location around or near the anus. Tumors are usually multiple. There is no fur over them, the skin is tense, and deep fistulous tracts with purulent-necrotic discharge often occur. The occurrence of tumors is associated with an increase in the body's level of male sex hormones (androgens), produced by special cells in the testes. A connection has been established between tumors of the perianal glands and tumors of the testes (Leydigoma) or hyperplasia of Leydig cells, which produce androgens.

Surgical removal of perianal gland adenomas is ineffective. Tumors persistently recur after removal, or new nodes appear in the perianal area. Due to the fact that these tumors are of dyshormonal origin, castration of the animal may be recommended, followed by long-term administration of female sex hormones (sinestrol at a dose of 1 mg per 5 kg of animal weight daily for 3-4 months). The ulcerative surface is epithelialized, tumor nodes are reduced and sometimes completely disappear, however, cessation of estrogen administration can lead to a re-enlargement of perianal tumors.

Lymphosarcoma(lymph node sarcoma) refers to a group of diseases with a general (systemic) lesion of the lymphoid tissue. The disease occurs in dogs aged 4-7 years and usually begins with a unilateral enlargement of the submandibular or other superficial lymph node, which is painless and retains mobility (stage I). In this period, the general condition of the animal is good, the appetite is preserved, no changes are noted in the peripheral blood. In the case of an increase in the submandibular lymph node, it is necessary to exclude the inflammatory process in the oral cavity (tonsillitis, dental disease), in which the enlarged lymph node is painful on palpation. The progression of the disease is expressed in an increase in the group of lymph nodes, which are a single immovable conglomerate with swelling of the surrounding tissues (stage II). No changes are observed in the blood either. Stage III is characterized by an increase in all superficial lymph nodes (cervical, axillary, inguinal, popliteal), which often leads to thickening and swelling of the limbs due to impaired lymph outflow (lymphostasis). Further development of the disease (stage IV) is accompanied by damage to the bone marrow and an increase in the liver and spleen, accumulation of fluid in the abdominal cavity (ascites) is possible. Immature lymphoid cell elements (blast forms) are observed in the peripheral blood. The general condition of the animal is characterized by lethargy, lethargy, lack of appetite, frequent, liquid stools, thirst, copious discharge of viscous saliva, and the dog sharply loses body weight.

The diagnosis of lymphosarcoma is made on the basis of puncture of the lymph node followed by microscopic examination of the puncture, in which immature (blastic) forms of lymphoid cell elements are detected. Lymphosarcoma is sensitive to modern antitumor drug therapy, which can cause a reduction in lymph nodes to normal size and stable complete remission lasting up to 3-4 months. Surgical removal of an enlarged lymph node is impractical, since this leads to rapid growth of the tumor at the surgical site and in other lymph nodes, i.e., it contributes to the rapid generalization of the process.

Sarcoma of the mesenteric lymph nodes (intestinal form of lymphosarcoma) is a rather rare disease and difficult to recognize because it does not have clear symptoms. Clinically, alternating constipation and diarrhea that are not amenable to conventional treatment, weakness, and weight loss are characteristic. Upon palpation, a tumor formation is detected in the abdominal cavity, which cannot immediately be associated with enlarged mesenteric lymph nodes. For a more accurate diagnosis, a trial laparotomy may be recommended, in which a conglomerate of enlarged mesenteric lymph nodes is detected. Treatment is only medicinal in specialized institutions.

Lymphocytic leukemia- is a tumor systemic disease of hematopoietic tissue; characterized by proliferation in the bone marrow, spleen, liver and other internal organs of immature (blast) cells of the lymphoid series. Occurs in relatively young dogs (average age 3-5 years). It begins with unexplained weakness, loose stools, and refusal to feed. Subsequently, pallor of the mucous membranes, shortness of breath develop, and a rise in body temperature to 40-41 ° C is possible. Superficial lymph nodes are not enlarged or enlarged very slightly. In lymphocytic leukemia, the proliferation of blast cells in the bone marrow and their release into the peripheral blood contribute to the suppression of hematopoiesis, which leads primarily to deep anemia (reduction in the number of red blood cells to 1.5 million, hemoglobin to 70 g/l) and leukocytosis (40-50 thousand). ), and not only a shift in the blood count to the left is characteristic, but also an absolute increase in the number of lymphocytes. The number of blast cells in the bone marrow and peripheral blood reaches 50% or more.

With the help of modern antitumor drugs, it is possible to cause a short-term remission and a general improvement in the animal’s condition, but in general the prognosis is unfavorable: depending on the stage of the disease, dogs live no more than 4-6 months, subject to intensive antitumor treatment.

Thus, the state of hematopoiesis in dogs with lymphosarcoma and lymphocytic leukemia has characteristic features that should be taken into account in differential diagnosis. Thus, in dogs with lymphosarcoma without bone marrow involvement, hematological parameters practically do not differ from the norm. The progression (generalization) of lymphosarcoma is accompanied by the appearance of blast cells in the bone marrow and peripheral blood. In lymphocytic leukemia, blast cells are found in the bone marrow and peripheral blood from the very beginning of the disease, and their proliferation in the bone marrow leads to suppression of hematopoiesis.

Transmissible sarcoma better known as venereal sarcoma. It occurs in both males and females aged 2-4 years, more often in stray dogs or dogs leading a relatively “free” lifestyle (huskies, hounds). The tumor is located on the mucous membrane of the genital organs and is transmitted from individual to individual only through sexual contact, being extremely contagious. The tumor is transmitted by living cells, which, during sexual intercourse, break off from the tumor and are implanted on the mucous membrane of the partner’s genitals. The tumor does not metastasize, and even in advanced cases, regional (inguinal) lymph nodes are free of metastases. You can often see the spread of tumors throughout the mucous membranes of the mouth, nose and eyes, which is not metastasis, but mechanical implantation of living tumor cells, which occurs, for example, when a dog licks a tumor.

The first clinical sign of a tumor is the release of drops of blood from the external genital organs, which, when examined, reveal a loose bleeding formation on a wide base, resembling a cauliflower.

Transmissible sarcoma occupies a special position among canine tumors because it is clearly contagious, i.e., it is not a tumor in the strict sense of the word. At the same time, according to the microscopic structure, it has all the signs of a malignant tumor, and it should be attributed to the group of alveolar-type sarcomas.

Transmissible sarcoma of the genital organs does not pose an immediate danger to the life of the animal, however, treatment should begin as soon as the diagnosis is made. Surgical removal of the tumor is possible, but it stubbornly recurs if radical excision is not performed, and this is associated, especially in males, with the need for careful hemostasis and suturing of a large defect in the cavernous bodies and mucous membrane of the penis. Local irradiation of the tumor with gamma or X-rays gives good results. The tumor is also sensitive to modern antitumor cytostatics (cyclophosphamide, vincristine).

Tumor of the vaginal wall(leiomyoma) occurs in old dogs (average age 10-11 years) and is benign in nature. In practical terms, there is a need to differentiate the tumor from transmissible sarcoma. The tumor of the vaginal wall has a dense consistency, does not bleed, the mucous membrane covering it is dry, and the submucosal blood vessels are full of blood.

The tumor may grow in the direction of the tissues surrounding the vagina. In this case, it can be palpated in the perineum in the form of a formation located in the depths of the small pelvis, which can lead to impaired urination and defecation.

Surgical removal of superficial tumors of the vaginal wall is not difficult. If the tumor is located deep in the pelvis, then access through the perineum is recommended, but in this case, removal of the tumor is associated with the danger of damaging the urethra, into which a catheter should be inserted before surgery.

Testicular tumors are easily detected by external examination and palpation of the scrotum, although they do not immediately attract the attention of dog owners. Usually the tumor develops in one testis, but in 10-15% of cases it occurs in both. It is typical that when a tumor occurs in one testis, the second one atrophies. About a third of all tumors develop in the undescended testis and in young dogs (average age 6-7 years). In a descended testis, a tumor occurs at an older age (9-10 years). An undescended testis with a tumor is located either in the inguinal canal, which is easy to detect by palpation, or in the abdominal cavity, where detecting a tumor is associated with certain difficulties.

According to the histological structure, testicular tumors can be divided into three types: seminomas (tumors of the seminal epithelium), Sertoli cell tumors (Sertoliomas) and Leydig cell tumors. Clinically, all these tumors behave differently. Thus, sertoliomas produce female sex hormones (estrogens), a prolonged increase in the level of which leads to suppression of secondary sexual characteristics and changes in the behavior of males. Dogs with sertolioma have symmetrical hair loss in the chest, abdomen, and sides of the hind legs. The coat becomes dry and brittle, the skin thickens, especially the scrotum, the mammary glands enlarge, the prepuce decreases, and sexual activity decreases. However, it would be incorrect to say that the described picture is characteristic of all sertoliomas. A certain proportion of tumors do not have such manifestations, but it has been noted that the effect of estrogenemia in sertoliomas is much more pronounced when the tumor occurs in a testis that has not descended from the abdominal cavity. After removal of the tumor, the phenomena of feminization disappear quite quickly: already 4-6 days after the operation, the level of estrogen in the urine decreases to normal. Sertoliomas metastasize late.

Tumors from Leydig cells (Leydigoma) usually arise in the descended testis and produce male sex hormones (androgens), the long-term elevated level of which in the body creates a constant background that contributes to the occurrence of tumors of the perianal glands. In practical work, it is quite common to see tumors of the testis (leidigoma) and tumors of the perianal glands at the same time. Leydigomas are benign and do not metastasize.

Seminomas do not have hormonal activity and usually develop in the descended testis of old dogs (average age 10-11 years); metastasize rarely, mostly to regional (inguinal) lymph nodes.

Tumors of the testes, regardless of their histological structure, have a relatively slow growth, do not germinate the membranes of the testis, and their surgical removal is not difficult, especially if the testis affected by the tumor is located in the scrotum or inguinal canal. The most crucial moment in the operation is the ligation and intersection of the feeding artery. Removal of a testicular tumor located in the abdominal cavity is performed in accordance with the general rules for abdominal operations.

Prostate tumors- very rare, although non-tumor enlargement of the prostate (hypertrophy) is common in dogs older than 10 years. The probability of hypertrophy turning into cancer is extremely low, no more than 1%. Prostatic hypertrophy for a long time does not have any clinical manifestations, and only in cases where its increase leads to compression of the rectum, characteristic symptoms begin to appear. Usually, owners note in dogs a gradual lengthening of the act of defecation, associated with the impossibility of complete emptying of the intestines. Prolonged tenesmus leads to the development of perineal hernia and even prolapse of the rectum.

Prostate hypertrophy occurs in conditions of long-term hormonal disorders and is possibly associated with an increased level of male sex hormones (androgens) in the body. It is also known that hypertrophy occurs, as a rule, in males who did not have matings.

Distinguishing prostatic hypertrophy from cancer using clinical techniques is almost impossible. Prostate cancer in dogs metastasizes late; the tumor has a predominant tendency to grow locally, destroying surrounding tissues and growing into the urethra or bladder. In these cases, the appearance of blood in the urine is typical.

Treatment of prostate hypertrophy and cancer is mainly symptomatic. Sometimes the administration of large doses of sinestrol or castration helps.

Bone tumors occur in dogs aged 6-7 years, although they are believed to occur earlier. Developing slowly, sometimes for many years, they do not show themselves in any way. The first clinical signs of a tumor, if it develops in the bones of a limb, are lameness and a clear reluctance of the dog to get up from its place, especially in the morning, for which the dog owners consult a veterinarian. During this period, when palpating the limb on which the dog is limping, a tumor may not be detected, or a small dense, moderately painful thickening near one of the joints is detected. Unfortunately, it happens that lameness begins to be associated with an injury that allegedly occurred in the past, and the dog is prescribed compresses or other warming therapy, which in this case is absolutely contraindicated.

Bone tumors occur somewhat more often in males than in females, and almost exclusively in dogs of large breeds, such as St. Bernards, Great Danes, Newfoundlands, etc., i.e. in those dogs in which, during the period of intensive bone growth in length, Greater physical stress on the limbs, especially the chest.

About 80% of tumors are localized in long tubular bones, and in the thoracic limbs 3 times more often than in the pelvic limbs. Tumors can also occur in the ribs, vertebrae, flat bones of the skull, and iliac bones of the pelvis, but much less frequently than in the extremities. It is characteristic that in the bones of the extremities, tumors are located mainly in areas corresponding to growth zones, namely in the metaphyses. Most often, a tumor in the humerus is localized in the proximal metaphysis, and in the radius, femur, and tibia - in the distal metaphysis.

Bone tumors can be recognized using histological (biopsy) and x-ray examination methods. The histological structure of the tumors is quite diverse. Benign tumors (osteoma) are usually localized in the ribs or bones of the skull. The most common (up to 85%) of malignant tumors is osteogenic sarcoma, i.e. a tumor arising from bone tissue. Chondrosarcoma, fibrosarcoma, and osteoblastoclastoma are much less common.

Clinically, all of the listed bone tumors do not have specific signs, and it is not possible to distinguish one from another using conventional techniques (palpation). X-rays reveal characteristic features that help establish the correct diagnosis.

Thus, with osteogenic sarcoma, an area of ​​bone destruction with increased bone formation (osteosclerotic type) or bone resorption (osteolytic type) is usually clearly visible. A characteristic feature is a kind of osteophytes, or outgrowths, which have the shape of a “visor” located at an angle to the long axis of the bone and representing a reaction of the periosteum in the form of its detachment. Another characteristic sign of osteogenic sarcoma is the formation of thin calcifications with a direction perpendicular to the bone, forming a “fan” pattern. The spread of osteogenic sarcoma into the surrounding tissues leads to the formation of an extraosseous component, in which fields of ossification develop in the form of flocculent or cloud-like compactions, visible on radiography.

Fibrosarcoma and osteoblastoclastoma are difficult to distinguish on x-ray from osteogenic sarcoma. Histological confirmation of the diagnosis is required. X-ray features of bone chondrosarcoma include the presence of large foci of osteodestruction and the absence of osteophytes, “visor” and ossification of the extraosseous component.

Establishing a diagnosis using radiographs alone is impossible, even if the doctor has some experience. The leading role in this case belongs to the histological study of the material obtained by incisional biopsy, which, by the way, does not have any negative consequences for the sick animal, as some believe.

The final clarification of the diagnosis is based, therefore, on a combination of clinical, radiological and histological data. Accurate determination of the nature and nature of the bone tumor is important in that it determines the prognosis.

Bone tumors grow relatively slowly, but nevertheless their development proceeds through certain stages and corresponds to certain clinical stages. If the tumor is palpable as a small, moderately painful mass that is primarily a reaction of the periosteum, and the radiograph shows limited bone compaction that does not extend beyond the cortex, then this stage can be graded as I. A clearly palpable painful mass that has a pronounced reaction on the radiograph periosteum (osteophytes, “visor”), corresponds to stage II. Further increase in the tumor, swelling and tension of the skin, the appearance of weeping ulcerative surfaces on it, enlargement of the regional lymph node (metastasis) means the transition of the process to stage III. In case of adynamia of the animal, refusal to eat, coughing, or sudden loss of body weight, it is necessary to take a chest x-ray, and if multiple metastases to the lungs are visible, then this corresponds to stage IV.

Treatment of bone tumors is undoubtedly the most difficult problem of modern oncology. In medical oncology, schemes of drug and radiation exposure have been developed that can significantly suppress tumor growth. These regimens can be used in the treatment of bone tumors in dogs, but only in specialized institutions. However, in general, the prognosis of bone tumors in dogs remains unfavorable, especially in the case of osteosarcoma, with which dogs live no more than 2-3 months (in the absence of specific antitumor treatment). The life expectancy of dogs with chondrosarcoma, especially with fibrosarcoma and osteoblastoclastoma, is up to 5-6 months.

Speaking of bone tumors in dogs, one cannot fail to mention secondary, i.e., metastatic, bone tumors, which are most often metastases of breast cancer. These tumors are usually localized in the area of ​​the diaphysis of one of the long bones, are painful on palpation, cause lameness in dogs, and radiologically are characterized by a focus of osteolytic destruction in the absence of a periosteal reaction. A decisive role in the differential diagnosis is played by an indication that there was a malignant tumor of the mammary gland removed surgically in the anamnesis.

Thyroid tumors- the disease in dogs is quite rare, occurring at the age of 9-10 years. Tumors can be benign (adenomas) or malignant (cancers), the latter growing much faster. Located in the middle third of the lateral surface of the neck and protruding outward, tumors of the thyroid gland from the very beginning are motionless in relation to the surrounding tissues. They show an obvious connection with the trachea and, sometimes reaching considerable sizes, lead to its deformation and difficulty in breathing. The tumor usually affects one lobe of the thyroid gland.

The tumor is subject to surgical removal, and this operation is one of the most difficult. However, before deciding on an operation, it is necessary to make sure that there is no metastatic lesion of the deep cervical lymph nodes. An important point is also the careful selection of the neurovascular bundle passing in the area of ​​the operation. Due to the fact that the second lobe of the thyroid gland, not affected by the tumor, remains in the body, special therapy with thyroid-stimulating hormones in the postoperative period is not required.

Tumors of the tonsils They occur in dogs of all ages and are easily detected by careful examination of the oral cavity. The tumor usually affects one tonsil and is a soft, loose formation with a bumpy, sometimes bleeding surface. Histologically, it has the character of squamous cell carcinoma or, less commonly, lymphoepithelioma. Early metastasis of tonsil cancer to the deep cervical lymph nodes and lungs is characteristic. Treatment is only surgical, and radical removal of the tumor node with good hemostasis is necessary. In the presence of metastases, serious doubts arise about the advisability of surgery.

Tumors of internal organs in dogs are difficult to diagnose due to the absence of any specific signs and clinical manifestations that could indicate tumor damage to a particular organ. Even when the tumor reaches a significant size and changes occur in the body’s activity, even then the symptoms are of a very general nature, which does not allow one to suspect a tumor process. Such general phenomena, observed, for example, with tumors of the liver and spleen, include ascites, pallor of the mucous membranes, anemia, weakness, refusal to eat, and thirst. Ovarian tumors can clinically manifest themselves in estrus disturbances, prolongation of the estrus phase with constant bleeding. With tumors of the bladder and kidneys, hematuria, dysuria, weakness, and adynamia may occur. With stomach tumors, which are extremely rare in dogs, symptoms develop primarily associated with obstruction (vomiting of food, exhaustion, weakness).

With sufficient experience, a veterinarian can palpate a certain mass in the abdominal cavity and make a guess as to which organ the tumor is likely to come from, but there is usually no complete certainty. X-ray examination of animals in which a tumor of any internal organ is suspected provides very scanty data, even when air is introduced into the abdominal cavity. The use of radiocontrast agents to diagnose tumors is a complex procedure that requires special skills and good equipment that allows serial images to be taken.

In all cases where there is a suspicion of a tumor in the abdominal cavity, it is necessary to resort to diagnostic laparotomy if the general condition of the animal allows this surgical intervention.

It should be emphasized that the tactics of surgical treatment and the scope of surgical intervention are determined primarily by the histological structure of the tumor and the clinical stage of the disease.

It has already been said that there are factors that contribute to the emergence and growth of tumors. Such facts as the absence of mating and frequent false pregnancies, cryptorchidism and symmetrical alopecia or the presence of a tumor of the perianal glands, lameness in large dogs, prolonged tenesmus and perineal hernia in males, and other symptoms - all this should attract the special attention of veterinary specialists and form in them a feeling of oncological alertness. However, oncological alertness should not turn into overdiagnosis, that is, into a tendency to see a tumor everywhere, especially where it is not accessible to external examination, for example, in the abdominal cavity. In all cases, the doctor must be confident in his diagnosis or have sufficient grounds to suspect a tumor.

Many tumors in dogs respond well to surgical treatment if the diagnosis is correctly made, and the operation is performed at an early stage (without tumor invasion into surrounding tissues and metastatic spread) and performed according to the rules of ablastic surgery. The treatment of lymphosarcoma and osteogenic sarcoma is still ineffective, although with the help of modern drugs and methods of radiation and combined exposure, in some cases it is possible to achieve a significant extension of the life of sick animals.

Oncological diseases in dogs are practically no different from oncological diseases in humans. There are many theories of the origin of tumors. Some scientists believe that the cause of oncology in dogs is a virus (herpes virus, papillomavirus), others are the result of exposure to the body of chemical and physical carcinogenic factors (carcinogenic substances, radioactive radiation). At the same time, there are theories explaining the cause of oncological diseases in dogs by hormonal disruptions in the body or a violation of tissue development during ontogenesis. In recent years, the most likely cause of neoplasms in dogs is considered to be the result of cell mutations that occur at the genetic level.

A neoplasm is a group of cells in a newly formed tissue in which the processes of growth, differentiation and reproduction of cells are disrupted. Cancer tissue is characterized by tissue (cellular) atypia, progressive growth and relative autonomy from other tissues.

For neoplasms in a dog, the appearance of metastases with blood and lymph flow in various organs is characteristic.

Types of neoplasms in dogs.

All neoplasms are usually divided into benign and malignant. For benign neoplasms, it is characteristic that they grow slowly, often have their own capsule or membrane, do not grow into the tissues surrounding the tumor, do not metastasize, and after their removal there are practically no relapses.

Malignant neoplasms are characterized by rapid growth, germination into surrounding tissues, and give metastases. After their removal, they often reappear. During histological examination, malignant cells are poorly differentiated, so it is difficult to determine from which tissue they originate. When a malignant neoplasm occurs in the body of a sick dog, a profound metabolic disorder occurs, and symptoms appear in the organs affected by the tumor.

Depending on the type of tissue affected by the malignant tumor, veterinary specialists distinguish the following groups of malignant tumors:

• carcinoma is a tumor arising from epithelial cells.
• myosarcoma is a tumor of muscle cells.
• melanoma is a tumor of pigment cells.
• sarcoma is a tumor of connective tissue cells.
• Osteosarcoma is a tumor of bone tissue cells.
• lymphoma is a tumor of lymphatic tissue cells.
• glioma is a tumor of glial cells.
• Teratoma is a tumor formed from germ cells.

Additionally, other types of tumors occur in dogs.

Clinical picture. Veterinary specialists divide the available types of cancer in dogs into:

Mammary tumor in dogs

Breast tumors make up 50% of all neoplasms in bitches. The average age of affected females is 9 years. Histologically, tumors are divided into epithelial (benign - adenomas and malignant - adenocarcinomas), mesenchymal (benign - fibromas, chondromas, osteomas, myoepitheliomas, malignant - fibrosarcomas, chondrosarcomas, etc.) This type of tumors is determined by veterinary specialists of the clinic during a clinical examination of a sick dog , during palpation of the mammary gland, the veterinarian palpates tumors of various sizes. Which can be either single or multiple. Moreover, their diameter varies from 0.5 cm to 10 cm. Upon palpation, a veterinarian defines them as painless enlargements, often of a nodular consistency with a smooth or unevenly lumpy surface. Tumors that are small in size, grow slowly, have not grown together with the skin covering them, and are mobile relative to the pectoral and abdominal muscles are considered benign. With a malignant course, veterinary specialists note the rapid growth of the tumor, it is fused with the abdominal wall, and ulceration of the skin appears over the tumor. The malignancy of a breast tumor is indicated by the presence of metastases in regional lymph nodes or individual organs.

Treatment. Breast tumors that are less than 1 cm in diameter do not require any treatment at first. Owners of such dogs should have their dogs checked regularly by their veterinarian for possible growth in tumor size. Larger and faster growing breast tumors must be urgently removed surgically. If a malignant tumor is suspected (ulcerated surface, infiltrative growth, the tumor does not move relative to the abdominal wall), then the veterinarian must remove as much tissue as possible during the operation. If the dog’s inguinal lymph nodes are enlarged, they are also removed. Including If we are dealing with a tumor affecting several pairs of nipples, then it becomes necessary to excise the entire mammary line. When performing the operation, it is necessary to take into account that large blood vessels often pass through the upper and lower parts of the mammary gland complexes, during the operation it is necessary to resort to their ligation according to separately. In order to prevent surgical bleeding, they often resort to intravenous drip administration of lactated Ringer's solution before surgery. If as a result of the operation a sufficiently large cavity remains, and also if the bleeding cannot be stopped completely, we leave a cigarette drain. Then using absorbable suture material We sew the subcutaneous layer with a purse string suture. The skin is sutured with separate interrupted sutures.

Vaginal tumor

Tumors of the vagina. They are found mainly in older bitches. In this case, tumors are mostly benign (leiomyomas, fibromas, lipomas), malignant cancerous tumors or fibrosarcomas are rare in dogs. However, benign vaginal tumors can be either single or multiple and often have the form of polyps or cover large areas of the vaginal walls.

Clinic. With this type of tumor, a sick dog develops bloody or purulent discharge from the vagina. When the tumor is located in the posterior part of the vagina, we note an increase in volume in the perineal area. Sometimes a dog has difficulty urinating or defecating.

Treatment. Vaginal tumors are removed surgically.

Uterine tumor

Tumors of the uterus. This type of tumor in dogs is rarely recorded and they occur mainly in smooth muscles and are usually benign (leiomyomas). Disorders occur in dogs when, due to an increase in the size of the uterus, compression of other abdominal organs occurs or when adhesions and adhesions form at the site of mechanical irritation in the abdominal cavity. The owner may be alerted by the dog's frequent unnatural bowel movements from the external genitalia, miscarriage or absence of a fetus in a previously pregnant dog. Provoking uterine cancer in dogs is usually the use of hormonal drugs by owners that affect estrus. Tumors of the uterus in dogs are most often diagnosed in the last stages of their development. The dog from severe pain often begins to whine, there are disturbances in the activity of the intestines, drowsiness, apathy, tries to move as little as possible.

Treatment is surgical.

Testicular tumor

Testicular tumors. Found in older males. The most common types of tumors are leydig cell tumors, ledigomas, seminoma tumors, Sertoli tumors, sertoliomas.

Clinic. The testicles are enlarged on clinical examination, palpation is nodular and hard.

Bone tumors. Bone tumors in dogs in most cases are malignant and tend to metastasize. Veterinarians most often have to deal with osteosarcomas, which are predominantly found in large breed dogs (greatest dogs, shepherd dogs, boxers, etc.). They are found mainly in the area of ​​the metaphysis, sometimes at the site of healing fractures.

Clinic. The disease in a dog is accompanied by lameness, the dog carefully steps while walking, quickly gets tired. On palpation at the site of the tumor, the dog reacts painfully.

Treatment. Conservative treatment with cytostatic agents is ineffective. Surgical treatment consists of immediate amputation and further chemotherapy.

skin tumor

Skin tumors. It is quite rare in dogs. It is quite difficult for dog owners to notice this type of tumor, since the dog is covered with a layer of fur. Usually, this type of tumor can be detected during water procedures, when dark spots resembling moles are found on the skin. The color of these moles can vary from pinkish to dark gray. Sertolioma is a skin tumor that arises from Sertoli cells. Boxers are predisposed to this tumor.

Mast cell tumors (mastocytoma, with multiple tumors - mastocytosis) are widespread skin neoplasms. The tumor consists of transformed mast cells. It should be noted that in humans this is one of the rarest tumors, so rare that it is not presented in every manual for the diagnosis of skin tumors in humans.

SLIDE 1. Mastocytoma in dogs (Mast cell tumor)

Mast cell tumors (mastocytoma, with multiple tumors - mastocytosis) are widespread skin neoplasms.
The tumor consists of transformed mast cells.

SLIDE 2. Mast cells. Schematic drawing

Mast cells (mast cells, mast cells) are highly specialized immune cells of the connective tissue of vertebrates, analogues of blood basophils. Participate in adaptive immunity. Mast cells are scattered throughout the body's connective tissue, especially under the skin, around lymph nodes and blood vessels; found in the spleen and bone marrow. Like basophils, the surface of mast cells has receptors for IgE immunoglobulins.

Mast cells contain large numbers of cytoplasmic granules that stain with cationic dyes. The granules include proteoglycans (heparin), histamine, interleukins and neutral proteases. When activated (for example, during an allergic reaction), mast cells release the contents of the granules into the surrounding tissue. Mast cell degranulation with the release of histamine is an immune-mediated reaction through IgE, induced by certain antigens - an immediate hypersensitive reaction.

Some antigens can cause massive degranulation of mast cells, causing urticaria and more serious reactions, including allergic shock. In addition, mast cells also react to any tissue trauma, in which case degranulation is triggered by other cytokine mechanisms. In addition to histamine, which dilates blood vessels, mast cell granules contain heparin, platelet activating factor, and other substances.

SLIDE 3. Spread of mastocytoma

It should be noted that in humans this is one of the rarest tumors, so rare that it is not presented in every manual for the diagnosis of skin tumors in humans.
It is also a fairly rare tumor in cattle. In cows, mastocytoma is malignant and multiple in nature. In this case, the tumor can be either a metastasis from internal organs or a primary skin tumor. Found in the spleen, muscles, gastrointestinal tract, and uterus.

SLIDE 4. Spread of mastocytoma

This is a fairly rare tumor in horses. They usually appear as soft tissue tumors on the scalp, neck, torso, and legs. Mastocytoma is also a rare tumor in pigs. But if in cows these are multiple malignant tumors, then in pigs these are, as a rule, benign single tumors.

SLIDE 5. Mastocytoma in dogs and cats

Dogs and cats are leaders in the animal kingdom in causing mast cell tumors.

So, in dogs and according to A.S. White (2003) the incidence of mastocytes is 21% of all skin tumors of dogs. The terms mast cell tumor and mastocytoma are used interchangeably.
As a rule, tumors in dogs are single in nature; less often they occur in the form of multiple nodules. Sometimes mastocytomas can be partially reduced, decrease in size and become pale, but then, as a rule, they increase again.

Almost always, mastocytomas are susceptible to ulceration; they cause itching and dogs can even chew parts of them. The classification of mastocytomas in dogs still remains an unexplored area; it is not possible to identify morphological signs of the tumor that allow us to speak unambiguously about the prognosis of the disease.

Lesions of the gastrointestinal tract and spleen are more common in cats than in dogs. Up to 50 percent of all cases of mastocytomas in cats involve the spleen or intestines. Most often they are found in the muscle layer of the intestinal wall. Mastocytoma is the third most common intestinal tumor in cats after lymphoma and adenocarcinoma. In addition, a mastocytoma has been identified in cats, clinically occurring as a histioma in dogs, in the form of a small red nodule, which after ulceration can resolve spontaneously.

SLIDE 6. Predisposition to mastocytoma
depending on the dog breed

Among dogs, there is a pronounced breed predisposition: in descending order, the following are predisposed to mastocytoma: Boxer, Staffordshire Terrier, English Bulldog, French Bulldog, Basset Hound, Boston Terrier, Beagle, Shar Pei.

SLIDE 7. Mastocytoma - simulator

Mastocytomas in dogs are known among veterinary oncologists as the great mimics because their appearance is so varied that they can mimic virtually any skin disease. Mastocytomas can range from a simple wart or soft subcutaneous lipoma to moist dermatitis, and the owner of the animal will suspect a dangerous tumor in the very latter case. Therefore, any skin lesions should be subjected to cytological examination.

However, most cases of mastocytomas are diagnosed as small nodules on the skin that are prone to erosion. As a rule, the hair at the site of the lesion falls out, and the lesions themselves itch, causing the dog to scratch the affected area. Most often the tumors are single, but in approximately six percent of cases they are multiple, which is especially common in Boxer and Pug dogs.

Any, even minor, manipulation of the tumor can lead to its redness and swelling, due to degranulation of the mast cells that make up the tumor. In rare cases, mastocytoma is a very malignant tumor, in which case symptoms such as loss of appetite, vomiting, diarrhea, and anemia develop. The presence of these signs usually indicates mastocytosis, in which malignant mast cells spread throughout the body.

SLIDE 8. Classification of mastocytes by degree of differentiation

DIAGNOSIS OF MASTOCYTES IN DOGS
(Mast cell tumors in dogs)

There are practically no specific clinical manifestations characterizing mastacytomas, but the tumor is easily diagnosed using fine-needle aspiration biopsy. Puncture of the tumor with a thin needle is practically painless for the dog; the resulting material is placed on a glass slide, smears are prepared, stained according to Romanovsky-Giemsa and subjected to examination. Mastocytoma cells are large, round cells containing large numbers of darkly colored granules. When a large number of granules are released and their systemic action is released, vomiting, stomach ulcers, shock, and even death of the animal can develop.

Mastocytoma cells behave very unpredictably; it should be noted that at the moment there are no absolute criteria that can convincingly distinguish a tumor that will be aggressive, recur, metastasize and lead to fatal consequences, from a tumor, after removal of which recovery will occur.

To determine the prognosis, it is extremely important to classify the tumor according to the degree of differentiation. Differentiation reflects the degree to which malignant mastocytoma cells differ from normal, benign mast cells. The degree of differentiation, as a rule, correlates with the behavior of the tumor, the possibility of its recurrence, the rate of growth and metastasis, and, consequently, the survival of the sick animal.

Table 1

Classification of mastocytomas in dogs according to the degree of differentiation

Stage	degree of cell differentiation	cytological features	probability of relapse, %
stage I	highly differentiated	layers and homogeneous (same size and morphology), mononuclear cells with stereotypical granulation	25
stage II	moderately differentiated	the layers of cells are heterogeneous, there are single cells with altered morphology	44
stage III	low-grade	almost all cells of different morphology, many multinucleated, unequal, ugly cells, mitoses	76

However, classification of a tumor only by the degree of differentiation does not always give an accurate prognosis, so clinical classification of the tumor, based on standard criteria proposed by WHO, is also very important.

SLIDE 9. Clinical classification of mastocytes in dogs according to WHO criteria

table 2

Stage	Clinical features of the tumor	Probability of relapse, %
stage I	Single tumor without involvement of a regional lymph node	25
stage II	Single tumor involving a regional lymph node	44-100
stage III	Multiple tumors with or without involvement of regional lymph nodes	76-100
Stage IV	Any tumor with distant metastases	100

It is easy to notice that from a clinical point of view, such a classification is more difficult to use; it turns out that from the second stage it is already necessary to apply the most stringent measures, including chemotherapy.

In addition, the position of the mastocytoma on the body of the animal also affects the prognosis. Mastocytomas involving the lips, head, groin, and distal extremities have a poorer prognosis than tumors affecting various parts of the neck and trunk, as well as proximal extremities.

Fast-growing tumors that double in size in a week tend to be more difficult to treat than those that double in size in a year. Naturally, the pathologist will be able to determine the degree of differentiation of tumor cells only after a biopsy and cytological examination. Fine needle biopsy and examination of tumor cells is a must in the investigation of any skin tumor in dogs.

The size of the tumor also matters, the larger the tumor, the more difficult it is to remove it, the longer it exists, the higher the likelihood of metastasis.
And finally, the consistency, the presence of inflammation and adhesions with surrounding tissues, is an important point for the prognosis. If the tumor is well demarcated from the surrounding tissues, sometimes even hanging from the body, and is classified as stage 1 in both classifications, even with a huge size, the animal has a good prognosis for a complete cure.

The possibility of complete removal of the tumor greatly influences the prognosis; therefore, the proximity of the tumor to nerve trunks and vascular bundles, vital organs, and in anatomically inconvenient areas for removal worsens the prognosis. Dogs with stage I or II mastocytomas have a good prognosis, provided they can be completely removed. There is evidence that up to 23% of stage I or II mastocytes recur. Any mastocytoma found in the gastrointestinal tract, on the paws or on the face has a very cautious prognosis. Recent studies have found that tumors in the groin do not have a poor prognosis, which refutes earlier studies.

TREATMENT FOR MASTOCYTE

Treatment of mastocytes in Russia is based on surgical treatment and chemotherapy according to indications; only rare clinics use radiation therapy. Recommendations for chemotherapy are based on tumor grade and clinical findings. The surgical method is contraindicated for multiple mastocytomas and poorly differentiated mastocytomas, at least without the support of chemotherapy.

If a low-grade mastocytoma is detected, the veterinarian will most likely prescribe, before surgical treatment, an X-ray diagnosis or ultrasound of internal organs to exclude metastases, as well as biochemical and morphological blood tests to exclude severe anemia and basal cell leukemia. Bone marrow biopsy has now been abandoned because the data from this study are not very informative.

SLIDE 10. Histological examination

For single mastocytomas, surgical excision of the tumor with a wide coverage of healthy tissue is always recommended, with the goal of radical excision of the tumor. By radical tumor removal we mean the removal of at least 3 cm of healthy tissue bordering the tumor.

After removing the tumor, a piece of tissue 0.5 * 1 cm is cut from the edge of the removed tumor on 3-5 sides (depending on the size of the removed tumor), they are placed in 10% formalin, and sent to a pathologist for examination. Histological examination will determine whether tumor cells remain in the border tissue or not. If the result of the histological examination is negative, then they speak of “clean edges.” If the pathologist suspects the presence of mastocytoma cells in the remaining tissue of the site after surgery, we refer to this as “dirty edges.”

An early aggressive surgical policy gives the best results for well-differentiated and moderately differentiated mastocytomas. If there are “clean edges” after surgery, chemotherapy is usually not required.

Poorly differentiated mastocytomas, multiple tumors, recurrent tumors, or tumors with dirty margins (those that for anatomical reasons could not undergo more aggressive surgical therapy) often require subsequent or “add-on” therapy.

Chemotherapy refers to the administration of certain cytostatic drugs to delay/prevent tumor growth and spread. Chemotherapy is used after surgery and as monotherapy if surgery is contraindicated (old animal, presence of metastases, late treatment).

SLIDE 11. Typical treatment options for mastocytes in dogs

A typical chemotherapy regimen will begin with prednisone, and if no positive results are obtained within two weeks, the CVP protocol will be prescribed: cyclophosphamide, vinblastine and prednisone. Tagamet will generally be used to minimize stomach irritation from prednisone, as well as counteract the histamines released by existing mast cells.

Table 3

Typical Treatment Options for Different Stages of Mast Cell Tomas

Stage	Processing options
"clean edges"	surgical removal of the tumor no further treatment required
"dirty edges"	surgical removal of the tumor; wider surgical removal of tissue with repeated histological examination of the wound edges
"clean edges"	surgical removal of the tumor prednisone for at least 6 months
"dirty edges"	surgical removal of the tumor; wider surgical removal of tissue with repeated histological examination of the wound edges; prednisone for at least 6 months

Prednisolone is the most commonly used drug for mast cell therapy. This medication is well tolerated in dogs and is usually prescribed for up to six months. If no new tumors appear during this time, your doctor may stop the drug completely.

Side effects of prednisolone include weight gain, increased appetite and thirst, skin infections, and shortness of breath. Sometimes, gastrointestinal disorders, stomach ulcers and pancreatitis are noted. In this case, additional medications are used to reduce side effects.

SLIDE 12. Therapeutic protocol for inoperable mastocytes

Protocol CPV for the treatment of mastocytes in dogs . Used for the treatment of multiple tumors, before surgery for large tumors in inconvenient anatomical areas for removal for those tumors that cannot be removed.

Combination chemotherapy can be effective in controlling tumor growth and spread throughout the body over many weeks, months, or even years. A complete cure in this case is impossible, but some dogs tolerate therapy very well and can live up to 2 years or more, sometimes reaching the age of biological aging.
The 6-month protocol for such therapy includes three drugs (Table 4).

Table 4

Therapeutic protocol for inoperable mastocytes (CPV protocol)

A drug	Dose	Frequency of administration
prednisolone	individual	daily intake in the form of tablets, possibly administered by the owners, for 6 months.
vinblastine	individual	drip administration, every 21 days
cyclophosphamide	individual	a drug given by the owners orally on days 8, 9, 10, 11 of a 21-day cycle

Side effects. The side effects of prednisolone are discussed above. Vinblastine and cyclophosphamide cause nausea and vomiting. The most severe side effects are associated with the occurrence of systemic infections due to a decrease in immune status. Massive degranulation of mast cells is also possible, which can lead to shock, but such side effects are rare and can be monitored by doctors.

Forecast. Factors that influence prognosis are the degree of tumor differentiation (best prognosis for high-grade tumors and worse prognosis for low-grade tumors), adequate surgical resection (clean margins), and tumor location. Dogs with poorly differentiated, multiple or recurrent tumors, or those with tumor invasion into the bloodstream and vital organs, always have a very guarded prognosis.

There are now new drugs available to treat mastocytes, such as Toceranib, a tyrosine kinase inhibitor, which was recently approved by the US Food and Drug Administration for the treatment of mastocytes in dogs. But unfortunately this drug is not yet available in Russia.

Monitoring after therapy. All dogs that have had mastocytomas removed should be under constant supervision by veterinary oncologists. Since early detection and subsequent treatment of tumor recurrence increases the likelihood of successful therapy. You will likely be asked to bring your dog in for evaluation every 6-8 weeks after surgery, or every 21 days for chemotherapy. Blood tests and tissue aspiration biopsy in the surgical area are a necessary condition for full patient monitoring.

SLIDE 13. Mast cell tumor with good prognosis

Slide 13 shows a tumor of a young female Boxer breed. As you can see, this is a solitary tumor that has no tendency to spread to regional lymph nodes. Cytological examination revealed layers of identical polygonal cells with a large nucleus. The cells have well-defined nuclei with a central location. Basophilic dust-like granularity is noted in the cytoplasm. It is clearly visible that this granularity is the same in all presented cells, being denser along the periphery of mastocytes.

According to the degree of differentiation, the tumor is classified as a well-differentiated mastocytoma, according to the WHO stage 1 tumor. With wide excision of the tumor, the prognosis for this animal is favorable. The breed of the dog also speaks in favor of a favorable prognosis; as a rule, in Boxers the disease progresses more benignly than in other dog breeds.
However, long-term monitoring by veterinary oncologists is necessary.

SLIDE 13. Mast cell tumor with good prognosis

Slide 14 shows a mastocytoma in a female bull terrier aged 4 years. Quite a large tumor on the back of the thigh, regional lymph nodes are not enlarged and painless, their cytopuncture gave a negative result for the presence of mastocytoma cells. The tumor is mobile, not fused to tissues.

Cytological examination reveals layers and islands of polygonal cells with pronounced polymorphism (cell sizes and shapes are different). The location of the nuclei in the cells is not the same; in some mastocytes the nucleus is located centrally, in others it is eccentric or on the periphery of the cell. The granularity in the cells is uniform in morphological characteristics, but its “density” is different; in some mast cells it completely fills the entire cell.

Based on clinical data, we classified it as stage 1 mastocytoma, and according to cytology as moderately differentiated mastocytoma, that is, stage 2.
After surgical removal, the edges of the surgical wound were sent for histological examination, and the conclusion was “clean edges.”
In our opinion, such a tumor does not require additional therapy.

SLIDE 15. Mast cell tumor of a dog (Asian, 8 years old)

Large mastocytoma on the ventral surface of the abdominal wall in an 8-year-old Asian Shepherd female.
The tumor is partially fused with the surrounding tissues, there is thickening of the skin above the tumor and around the tumor, the regional lymph node is enlarged, painless, a cytological examination of the aspirate from the lymph node yielded a negative result, stage 2 of the tumor according to the clinical classification.

Cytological examination of the tumor revealed regular layers of monomorphic cells with stereotypical basophilic granularity, which characterizes a well-differentiated mastocytoma, stage 1. Morphological and biochemical blood tests were carried out, they did not reveal any abnormalities, and surgery was scheduled. After surgical removal with wide excision of the tumor and regional lymph node, chemotherapy according to the CPV protocol was recommended.

The location of the tumor made it possible to carry out excision along healthy tissues, retreating almost 10 cm from the tumor. The animal’s owners refused histological examination of the edges of the surgical wound and chemotherapy, but after 8 months. We saw the dog in our clinic and she was absolutely healthy.

SLIDE 16. Mast cell tumor of a dog (Dog, 7 years old)

A small mastocytoma between the toes of the right limb in a male Great Dane at the age of 7 years.
The tumor is tightly adherent to the surrounding tissues, has an uneven surface, and areas of inflammation are clearly visible along the periphery of the tumor. Regional lymph nodes are calm. According to the clinical classification, the tumor is stage 1.

Cytological examination revealed regular layers of monomorphic cells with stereotypical basophilic granularity, which characterizes well-differentiated mastocytoma, stage 1.

Considering the close location of the mastocytoma to the vessels and the impossibility of wide resection of the tumor without damaging the fingers, high amputation of both fingers with tumor resection was recommended. However, the owners refused to amputate the fingers; after preliminary chemotherapy, tumor resection was performed. The edges of the wound were not examined, at the request of the owners.

After 10 days, when the sutures were removed, cells were aspirated from the inflamed tissue surrounding the suture; cytology revealed polymorphic cells of moderately differentiated mastocytoma. The animal's owners refused further chemotherapy. After 4 months The dog was admitted to the clinic in serious condition; adynamia, anemia, and refusal to feed were noted. The dog could not get to his feet. Infusion therapy did not lead to an improvement in the animal’s condition and it died within 3 days from the start of infusion therapy and treatment with histamine blockers. Of course, in this case it is necessary to take into account the age of the animal

SLIDE 17, 1 8 . Mast cell tumor

These slides show photographs of 2 mongrel dogs over the age of 10 years. One was diagnosed with a large mastocytoma in the area of ​​the lower third of the chest, and in the second, the upper third of the thigh.

Enlargement of regional lymph nodes was detected. The tumors are ulcerated, adherent to the underlying tissues; according to the clinical classification, both tumors are stage 2.
A cytological examination revealed layers of polymorphic cells; the cytological diagnosis was moderately differentiated mastocytoma, stage 2.

After the tumor was removed, both dogs were prescribed a course of prednisolone; the animal owners refused complex chemotherapy. Contact with the owners of one animal was lost; a 10-year-old male dog was in satisfactory condition 8 months after surgery and 2 months after the end of prednisolone therapy, with no tumor recurrence noted.

SLIDE 19. Multiple mastocytoma dogs

A female boxer aged 11 years was diagnosed with multiple tumors in the form of red nodules from 0.3 to 2 cm, rising above the skin. The nodules are sharply defined, without hair, some nodules are covered with crusts, they itch, the dog scratches them. The retropharyngeal and submandibular lymph nodes are enlarged. Clinical stage of mastocytoma is 3rd.

SLIDE 20. Poorly differentiated mastocytoma

Cytological examination of the tumor in this dog revealed irregular layers of polygonal, round and irregularly shaped cells. Severe atypia, there are cells with virtually no granularity, more like fibrobalsts.

In some cells the granularity is more pronounced than in others, the size of the granularity is sharply polymorphic, in some cells it is small and dusty; in others it is in the form of large grains and it fills almost the entire cell. With this cytological picture, we diagnosed mastocytoma from moderately differentiated to poorly differentiated, stage 3.

At the same time, the general condition of the animal is satisfactory, it is not exhausted, the dog willingly accepts food, and sometimes vomits on an empty stomach. A general blood test revealed slight anemia.
Surgery for this type of mastocytoma is contraindicated, and the animal is prescribed a course of chemotherapy according to the CPV protocol. To date, 9 months have passed since diagnosis. the dog is receiving a second course of chemotherapy, the general condition is satisfactory, considering the age of the animal, we believe that we have achieved good results.

SLIDE 21-26
(description in text)

A series of slides shows animals with the same clinical picture of the corresponding stage 2 mastocytoma, with damage to regional lymph nodes. It is necessary to note the very difficult location of mastocytes on the front part of the head, which sharply worsens the possibility of total excision of the tumor.

In our case, cytological examination revealed sharply polymorphic cells, some of them were multinucleated, the granularity in individual cells differed sharply in morphology and size (slide 26, 27, 28). With this cytological picture, we diagnosed poorly differentiated mastocytoma, stage 3.

In our opinion, the decision on surgical intervention should be made by a veterinarian in each specific case, taking into account the general condition of the animal, its age and cytological diagnosis. After one course of chemotherapy, we operated on all animals and received tumor recurrences in all cases. All animals received repeated courses of chemotherapy. Both Shar Pei and “Asian” tolerated repeated courses of chemotherapy well, tumor growth is being contained, but there is no complete recovery. But the animal owners are optimistic and ready for further therapy. During the second course of chemotherapy, the boxer developed signs of heart failure, the owners refused to continue treatment, and we do not know the further fate of this animal.

SLIDE 27.

Large mastocytoma in a 5-year-old male. A large ulcerated tumor with an unpleasant odor was found in the area of ​​the animal's right cheek. Regional lymph nodes are enlarged, and a chest x-ray reveals multiple opacities in the lungs.

The clinical condition of the animal is poor, severe asthenia and adynamia are noted, the dog does not stand up. Three days before the dog was admitted to the clinic, she was vomiting blood streaks and passing dark feces. On the day of admission, the animal refuses food, but greedily drinks water, after which it vomits. A general blood test showed anemia, leukocytosis, thrombocytopenia, and a biochemical study showed hyperazotemia.
Diagnosis of mastocytoma with distant metastases, stage 4 according to clinical classification.

SLIDE 28. Poorly differentiated mastocytoma

The slide shows a typical picture of a poorly differentiated mastocytoma. All cells are of different sizes, some cells have several nuclei from 2 to 10, the nuclei in the cells are not of the same size and shape. In multinucleated cells, both large and small nuclei can be found. There is a sharp shift in the nuclear-cytoplasmic ratio in favor of the nucleus; in some cells, the nucleus occupies almost the entire cell. The nucleoli in the cells are poorly expressed.

Granularity in cells is polymorphic, both in terms of tinctorial properties and in shape and size; in some cells it is dust-like, while in others it is in the form of large grains of irregular shape. There are always few mitoses in mastocytomas. This picture represents a poorly differentiated mastocytoma, stage 3.

Thus, this animal has an advanced end-stage malignant mastocytoma with clinical signs of systemic mastocytosis and a poor immediate prognosis. After explaining the situation, the owners decided to euthanize the animal.

SLIDE 29,30, 31. Differential diagnosis of mastocytoma

In our opinion, sometimes there may be problems in differentiating melanoma from mastocytoma. This differentiation is important because chemotherapy and prognosis are different for these tumors. In our practice, we have encountered a case when a melanoma was diagnosed with a mastocytoma with a good clinical prognosis in a medical laboratory. On the basis of an incorrect diagnosis, an incorrect prognosis was made and, accordingly, therapy. The dog was not operated on for a long time and eventually developed a stage 2 mastocytoma.

Why did doctors make the wrong diagnosis? We have already said that mastocytoma in humans is a very rare tumor, so rare that some cytologists and histologists, having worked for 20 years or more in the laboratory, have never encountered this problem. Naturally, such specialists lack alertness and special knowledge in diagnosing tumors in dogs and other animals. And when such a possible and very good specialist gets a canine mastocytoma, he can make an incorrect diagnosis.

Therefore, when sending material for research to a medical laboratory, the veterinarian must be sure that the specialists of this laboratory are familiar with the problem of diagnosing animal tumors.

Given this problem, we decided to give several signs that distinguish melanoma from mastocytomas.

1. Melanoma granules are usually black in color when stained according to Romanovsky-Giemsa, while melanoma granules are basophilic and range in color from dark purple to red.
2. The granularity of melanomas is more uniform in the form of coarse dust, and rarely varies in individual cells.
3. Granularity in melanoma cells often lies centrally, and clearing is noted along the periphery of the cell, while in mastocytes, on the contrary, granularity gravitates towards the edge of the cell.
4. In melanomas, mitoses are very common, whereas not every mastocytoma can have mitoses.
5. Vacuoles are often found in the cytoplasm of melanoma, whereas there are no vacuoles in the cytoplasm of mast cells
6. Melanoma is a very delicate tumor and therefore, when a smear is formed, the cells often lose their cytoplasm, leaving bare nuclei against a background of black granulation; mastocytoma cells are almost always intact.
7. Melanomas often form binucleate cells in a “fried egg” pattern, whereas mastocytoma does not form such cells.
8. In 10-15 cases, melanomas may be non-pigmented, in which case differential diagnosis is not a problem.
9. In difficult cases, you can always use special staining methods, which are used in the diagnosis of non-pigmented melanomas.

From the presented material it is clearly seen that mastocytoma is a complex clinical problem that requires serious assessment by both clinical veterinarians and pathologists. Diagnosis, prognosis, and adequate therapy are based on laboratory tests. To date, all the studies presented can be carried out at the Center for Diagnostics of Animal Diseases of the Rostov Regional Veterinary Laboratory.

In our opinion, the diagnosis of mastocytes is not difficult, but in some cases it may be difficult to assess the stage of tumor differentiation, in which case the complexity of the situation is assessed by the clinician and decides whether or not to perform surgery, and if so, to what extent. But after the removal of all tumors, especially with a good prognosis of the 1st and 2nd stages, in our opinion, it is important to conduct a histological control of tumor removal. Finding out "clean" or "dirty" edges remained after removal of the tumor, this is very important for making a decision on further therapy.

Neoplasms are uncontrolled growths of modified tissues that are unregulated by the body. Tumors in dogs can be localized in any part of the body. The risk of development increases in animals over 7 years of age. Characteristic features of tumors are endless reproduction, qualitative changes in cells, and damage to neighboring cells.

Causes and types of tumors in dogs

Based on a number of characteristics, neoplasms are divided into malignant and benign.

Benign tumors are characterized by slow growth and the presence of a capsule. Capable of reaching large sizes. They do not metastasize and rarely recur. However, due to compression of organs and blood vessels, severe dysfunctions can develop.

Malignant tumors are characterized by constant and uncontrolled cell division and rapid growth. They are not surrounded by a capsule, therefore they are able to grow into surrounding tissues, leading to their necrosis. They do not always reach large sizes, since irreversible changes from intoxication (including death) develop quite quickly. Malignant neoplasms metastasize, and if after surgical removal at least a few pathological cells remain among healthy cells, they recur, forming a new tumor.

A single cause of development has not been identified, but the influence of several factors is noted:

• Breed, hereditary predisposition.
• Exposure to carcinogenic substances.
• Irrational nutrition.
• Poor living conditions.

Dog tumor symptoms

Signs differ depending on location. Superficial neoplasms (skin, mammary glands, etc.) manifest themselves in the form of uncharacteristic compactions and local visible changes. In the early stages, they are difficult to diagnose because small nodules are difficult to palpate.

Lesions of internal organs cause changes not only in the function of the affected structures, but also worsen the general condition of the animal. Over time, metabolic disorders, qualitative changes in peripheral blood, and neurological symptoms become noticeable. They can often be suspected by their external manifestations.

Mammary tumors in dogs

They occupy three times the place in frequency among all cases of neoplasms. The highest risk of development is in unsterilized females. Externally, a tumor of the glands of dogs appears as one or more lumps, which are most often located close to each other in the area of ​​the milk bags. They are easily determined by palpation, but accurate confirmation of the diagnosis is possible only after taking a biopsy.

Tumor on a dog's stomach

The appearance of a lump on the abdomen may indicate the development of several types of tumors:

• Cancer of the skin or subcutaneous fat. In the early stages, it manifests itself in the form of small nodules, which merge into a conglomerate in a short time and reach large sizes.
• Peritoneal cancer. The focus is located inside the abdominal cavity on the sheets of the peritoneum, but over time it grows on the anterior abdominal wall and it becomes possible to directly palpate the tumor.
• A tumor in a dog’s abdomen may be a manifestation of damage to the gastrointestinal tract. As in the case of the peritoneum, the primary focus is in the cavity. The affected organ (stomach, intestines, liver, spleen) increases over time, which leads to its protrusion and the possibility of direct palpation.

Other localizations

Common localizations of neoplasms:

• A tumor on a dog's paw. Swelling of a soft consistency may indicate the development of skin or subcutaneous fat cancer. The danger in this case lies in distant metastases, which are carried with the bloodstream to all parts of the body. A solid neoplasm suggests osteosarcoma, a severe bone lesion that eventually involves the entire limb and bones of other parts of the body.
• Ear tumor in a dog. Most often, the appearance of swelling indicates an otohematoma - a rupture of the vessel inside the tissues, not associated with the tumor process. But in some cases, cartilage tissue cancer is detected, which over time can grow deep into the cranium.
• Tumor on the neck of a dog. A mass in the neck area may be a sign of the development of mastocytoma. This is a tumor consisting of transformed mast cells (immunoactive elements, tissue macrophages). Its danger lies in its rapid growth and negative impact on the immune system. Also, over time, compression of the esophagus, upper respiratory tract and main blood vessels is possible, which leads to death.

Diagnostics

Diagnostic measures are aimed at identifying the primary tumor site, its size and the presence of metastases (local or distant). To this end, the following are carried out:

• Clinical, biochemical blood tests.
• Ultrasound of the affected area (if possible).
• Detection of tumor markers in the blood.
• X-ray diagnostics (if necessary, using contrast agents).

After all the procedures have been completed, it is necessary to perform the “gold standard” of oncological diagnosis - taking a piece of pathological tissue (biopsy) followed by cytological analysis. After this, the type of tumor will become known, from which cells it grew, whether it is benign or malignant.

Treatment of tumors in dogs

Veterinary oncology is a rapidly developing field in which new treatment methods are constantly emerging. But surgical removal remains the leading method, taking into account the principles of ablastics and antiblastics. After the intervention, a histological analysis is performed, on the basis of which the question of further chemotherapy or radiotherapy is raised.

A number of neoplasms are treated with chemotherapy (late stages of breast and skin cancer). Such treatment is usually palliative and aims to reduce discomfort to improve quality of life.

Radiation therapy is less common in veterinary medicine. Surgical removal of a tumor in a dog remains the leading method, and radiation exposure is prescribed in the postoperative period to reduce the likelihood of relapses.

With this they read:

Papillomatosis in dogs - treatment of viral papillomatosis

If a dog has growths similar to papillae in the mouth area, benign papillomatosis can be suspected. This disease is characterized by the formation of warts, most often in the oral cavity, on the lips

Pannus of the eyes and corneas in dogs

Chronic keratoconjunctivitis that develops due to autoimmune disorders in dogs is called pannus. The disease affects the limbus and cornea. The infiltrate that forms over time under the cornea is replaced by scar tissue, which leads to vision deterioration and even loss.

Mammary tumors in cats: treatment and removal surgery

Mammary tumors are a common disease among cats. The malignant nature of the neoplasms is more common. Mostly older cats over 8 years of age are at risk. In females that were sterilized before the first sexual heat (“estrus”), these neoplasms practically do not occur.