Destruction of the jaw in a cat due to squamous cell carcinoma. Types of tumors in the mouth

In this article I will talk about what oncological diseases (cancer) occur in cats, what are the reasons for their development and the main symptoms. I will describe methods for diagnosing such diseases, methods of treatment, and what the owner should do if a terrible disease is detected in an animal. I’ll tell you whether feline oncology is dangerous for humans, and what prevention is.

Oncology is a disease in which cells begin to grow and expand into surrounding tissues completely uncontrollably. There are two types of malignant tumors: localized (when the tumor is limited to one affected area) and generalized (spread throughout the body).

The following cancers occur in cats.

Mammary cancer (breast in an animal)

Breast cancer (in first place in terms of prevalence).

It affects unsterilized cats, and is more often observed in pets that have never given birth.

Tumors or lumps grow inside the mammary glands (breasts). First, small dense balls appear, which gradually increase in size and at the last stage open. If left untreated, the animal will not live long.

Lymphoma

The abnormal cells affect the lymph nodes, first one, and then spread to the others and affect the liver and bone marrow. The disease manifests itself as compaction of the affected lymph nodes.

Sarcoma (fibrosarcoma, osteosarcoma, liposarcoma)

This type of cancer is the most aggressive, as it spreads throughout the body very quickly. May occur in the abdominal cavity of cats. Manifested by lameness, apathy, emaciation. The animal is in severe pain and is worried.

Sarcoma is the most aggressive type of cancer in cats.

Carcinoma and adenocarcinoma

This tumor affects the epithelial cells of internal organs and skin. It metastasizes very quickly. It can manifest itself as the formation of ulcers on the skin, damage to the gums and oral mucosa. The wound may open. If the lungs are affected, the cat may cough and pant. When the intestines are damaged, constipation, abdominal enlargement, and vomiting are observed.

This type of cancer affects the cat’s oral cavity and can affect the tongue, palate, and tonsils. In this case, non-healing ulcers form on the mucous membrane, and a strong and unpleasant odor appears. As the disease progresses, your pet may lose teeth and become crooked.

Almost all types of oncology are accompanied by such general symptoms as significant weight loss, apathy, and enlarged lymph nodes.

Squamous cell carcinoma is characterized by non-healing sores in a cat's mouth

Causes of cancer development

The exact reasons for the development of oncology have not yet been identified. Veterinarians believe that in most cases, the predisposition to cancer is inherited. Development factors also include long-term exposure to ultraviolet radiation, chemicals, etc. This type of cancer, such as lymphoma, is more often observed in pets suffering from the immunodeficiency virus or coronavirus infection.

Oncology can develop after vaccination. A lump often forms at the injection site, which after 2-3 months begins to transform into a tumor, so it is better to remove any tumors as soon as possible.

Methods for diagnosing cancer diseases

Diagnosis of cancer is carried out according to the following algorithm:

1. First, blood and urine are taken from the animal. Using tests, the functioning of internal organs is assessed.
2. X-ray. This type of examination allows you to detect metastases that have spread throughout the body. For breast cancer, an X-ray is called a mammogram.
3. Ultrasonography. In this way, tumors that are located shallowly can be detected. A biopsy is also performed using ultrasound.
4. Biopsy. It is carried out in three ways: using a puncture, an endoscope and surgically. In the first case, tumor particles are taken with a special needle (the material is drawn into a sterile syringe) or an endoscope (a few affected cells are pinched off). In the third method, biomaterial is collected during surgery, and the surgeon can completely remove the tumor or take only a small piece of tissue for examination.

Biopsy is the most accurate analysis for oncology

Treatment of breast tumors and other neoplasms

After all diagnostic measures have been carried out, the veterinarian will prescribe appropriate treatment.

There are three forms of cancer treatment: surgical removal of the tumor, chemotherapy or radiation.

The first method is the most effective, but it is carried out only if there are no metastases. The surgeon removes the malignant tumor under general anesthesia. After surgery, the animal is given chemotherapy to destroy any remaining abnormal cells.

Radiation therapy involves exposing a cancerous tumor to ionizing radiation. The procedure is carried out under general anesthesia in two ways: remote (irradiation occurs at a distance from the animal) and contact (the radiation source is introduced into the tumor itself or the cavity in which it is located).

The third type is chemotherapy. It is often combined with surgical removal of the affected tissue. The procedure involves intravenous infusion of toxic drugs that have a detrimental effect on cancer cells.

During chemotherapy treatment, your cat may lose all of its hair.

Such infusions are carried out several times according to a specific schedule. Usually the following drugs are used for treatment: Vincristine, Cisplatin, Epirubicin, Cyclophosphamide, etc. Medicines are prescribed only by a veterinarian.

Chemotherapy has serious side effects: hair loss, nausea, lethargy, and digestive problems.

Is cat tumor dangerous for humans?

Oncological diseases that affect cats are not at all dangerous for people. Many people believe that you can become infected with cancer if the tumor is opened, but this is not true. Numerous studies prove that oncology is not dangerous to others.

Disease Prevention

There are several effective preventive measures that will protect your pet from developing cancer:

1. Sterilization. This measure will protect the cat from developing mammary cancer almost 100%, and it is advisable to carry out the operation either before the first heat or immediately after it.
2. Isolate chemicals from your pet. There is an opinion that the development of oncology can be caused by prolonged exposure to chemicals on a cat. Therefore, it is necessary to keep fertilizers, detergents and other substances out of reach of the animal.
3. . This procedure will protect your pet from such serious illnesses as the immunodeficiency virus and coronavirus infection.
4. Balanced diet. It is very important to pay attention to the preparation of your pet’s diet. It is better to give preference to industrial feed of at least super-premium class. Such nutrition will protect the cat from developing pathologies such as diabetes, obesity, etc.
5. Removal from breeding of animals whose ancestors suffered from cancer. There is an opinion that a predisposition to cancer is inherited, so you should not get offspring from cats that have had sick pets in their family.

Oncology is not always a death sentence.

In the early stages, this disease can be treated, but for this it is necessary to contact a veterinarian at the first signs of cancer. If your pet begins to lose weight, refuses to eat, has a fever, or is limping, immediately take your pet to a doctor.

If the veterinarian has diagnosed late-stage cancer, you need to assess the cat's quality of life and consider humane euthanasia if she is in severe pain.

Cats experience oral diseases just as often as humans. They also have caries, tartar, gingivitis, and periodontal disease. Most often it is the gums that suffer. A tumor in a cat’s mouth is not a very common diagnosis, but quite dangerous.

Types of tumors in the mouth

A cat's mouth tumor can be of the following types::

• Benign. The most common benign neoplasms in the oral cavity in cats are:
• Gum fibroma. It is usually easy to notice as it is located near the gum line. The color may be the same as healthy gum tissue or slightly paler. Touching the fibroid does not cause significant discomfort. This type of tumor is often large in size and the tumor can cover several teeth.
• Epulis. This type of tumor forms on the gums. Doesn't happen often. In most cases, the size is not large, and the neoplasm occupies the gum area of ​​only about one tooth (permanent or baby).
• Malignant. The most common oral cancer in cats is squamous cell carcinoma. Initially, the tissue of the gums and tongue is affected, and then the disease spreads throughout the entire oral cavity. Carcinoma can invade all tissues and cause the cat's entire face to swell.

Main signs of a tumor

Suspicions about the presence of a tumor in the cat’s oral cavity may arise from such symptoms:

1. bad breath;
2. bloody spots in saliva;
3. bleeding from the mouth;
4. destruction of tooth enamel;
5. excessive salivation;
6. violation of the symmetry of the muzzle;
7. frequent sneezing;
8. nasal discharge;
9. the desire to actively scratch in the mouth area;
10. enlarged lymph nodes;
11. avoidance of chew toys;
12. weight loss;
13. lack of appetite.

If one or more signs from the list are present, you should consult a veterinarian and conduct a detailed examination of the cat. But don’t panic if you find tumors in your mouth. Many of the neoplasms may be benign in nature.

Diagnosis and treatment

In most cases, the presence of a tumor can be determined during an initial visual examination. A mouth examination is mandatory at every visit to the veterinarian. If the tumor is located in visually inaccessible places, examination methods such as ultrasound or x-ray are used.

If any neoplasm is detected, a biopsy is required. To do this, a small amount of tissue is collected for analysis. This is necessary to determine the nature of the tumor - benign or malignant.

A disease such as oral cancer in cats requires surgery and removal of the tumor. The greatest difficulty is presented by malignant formations. They tend to grow into all surrounding tissues and spread quite quickly. After removal of one tumor, relapses often occur. If the malignant tumor has managed to affect a large area of ​​​​tissue in the cat's mouth, then complete or partial removal of the lower jaw may be required.

The success of treatment largely depends on timely seeking medical help and the stage of the disease in the animal. After complete recovery, you should regularly examine the cat several times a year and undergo an examination by a veterinarian in order to timely monitor a possible recurrence of the tumor. Unfortunately, at the moment, oncology treatment does not always give a 100% successful result, neither in humans nor in dogs and cats.

Oncology is very often a death sentence, even if delayed in some cases. Unfortunately, even modern medicine cannot always at least slow down the development of this terrible disease. The same can be said for pets. The sooner the owner suspects something is wrong, the better. Especially if your pet has carcinoma. In cats, this pathology very often leads to death.

The lesions may appear as ulcers (with or without scabs) or resemble rough nodules that resemble warts. All these neoplasms are characterized by rather slow growth. A biopsy is needed to confirm the diagnosis. In some cases, this cancer can reach the lymph nodes, make its way to the lungs and even the bones. Then the symptoms will depend on the specific organ.

Complete surgical excision of all affected tissue is most preferable. Cryosurgery has proven itself well, when the tumor is frozen at a temperature of -196 degrees Celsius until it completely dies. All these methods are most effective when combined with chemotherapy. Prevention of relapse involves limiting the time susceptible animals spend in the sun.

Lenticular discoid dyskeratosis in cats

This type of cancer is uncommon in cats. It is believed to be associated with a suppressed immune system and infection with papillomavirus. Which animals are at greatest risk of disease? As we said, animals that have the RNA virus of feline papillomatosis in their bodies are at risk.

Proliferative lesions of the oral cavity are observed quite often in dogs and cats. The evaluation should include a complete physical examination, imaging studies, and histopathological examination of a sufficiently high-quality biopsy. Proliferative lesions are divided into reactive and tumoral. Some of them may be epulis - a tumor-like growth on the gum. The most common reactive gum disease is gum hyperplasia.

Tumor lesions include odontogenic and non-odontogenic tumors. The most common odontogenic tumors are peripheral odontogenic fibroma and acanthomatous ameloblastoma. The most common nonodontogenic neoplasms are malignant melanoma and squamous cell carcinoma.

The article discusses the prevalence, clinical presentation, and treatment options of proliferative lesions; special attention is paid to new treatment methods. For most proliferative lesions, surgery remains the most important component of the treatment plan.

Proliferative lesions of the oral cavity, epulis, reactive lesions, odontogenic tumors, non-odontogenic tumors.

Introduction
Oral cavity tumors account for approximately 5–10% of all tumors in dogs and cats. In dogs, a significant proportion of proliferative lesions are reactive or benign, while in cats, the majority of proliferative lesions are malignant.

Proliferative lesions or localized swelling in the oral cavity can present in a variety of clinical conditions, including infectious diseases. In addition, a non-healing ulcer that looks like an infection may very well turn out to be malignant. The exact nature of any lesion can only be determined by histopathological examination.

A biopsy is indicated for all proliferative or other suspicious lesions, such as non-healing ulcers. The main method of treating malignant neoplasms of the oral cavity is, if possible, radical surgery.

Clinical manifestations
Unfortunately, most owners are not accustomed to regularly examining their animals' oral cavity. Thus, when most patients consult a doctor, the disease is already at a late stage.

Clinical manifestations typically include halitosis, tooth mobility, exfoliation of tooth enamel, bleeding from the mouth, increased salivation; if the upper jaw is affected - nasal discharge. There are no obvious signs of pain in most patients, except in cases of tongue involvement or late stages of the tumor, when it interferes with chewing or leads to pathological fractures. Sometimes the main reason for contacting a veterinarian is a pronounced deformation of the animal’s muzzle.

Clinical examination
1. Direct examination
It is necessary to find out the clinical manifestations observed by the owner, the duration and progression of the lesion, previous treatment and its results. A complete direct examination should be performed to detect distant metastases.

Examination and palpation of the head can reveal asymmetry, increased pressure in the retrobulbar region (with distal lesions of the maxillary sinuses), bleeding from the mouth or nose, and bad breath. Space-occupying lesions should be carefully inspected and palpated, noting location, size and consistency of the lesion, color (abnormal pigmentation or loss of pigmentation), presence of ulceration and/or necrosis, attachment to underlying tissue, tooth displacement, any signs of abnormal tooth mobility, and changes in bone contour. An example of the survey is shown in Fig. 1.

Rice. 1. Proliferative lesion in a cocker spaniel. In the right half of the lower jaw there is a lesion 4 cm wide, dense, of normal pigmentation, ulcerated due to trauma by opposing teeth, fixed to the underlying bone. The teeth are displaced, but not mobile.

Regional lymph nodes should be palpated and their size, shape and consistency assessed, as well as possible attachment to surrounding tissues.

2. Visualization methods
Radiographic monitoring of the condition of the affected jaw is mandatory. In most cases, it is best visualized with screenless dental radiography and intraoral radiography.

Bone infiltration can be diagnosed by identifying differences in the severity of resorption and/or formation of new bone tissue. Bone resorption with standard techniques is visualized only when about half of the mineral content of bone tissue has been lost. Some malignant tumors may also show signs of tooth root resorption. Common radiological signs are shown in Table 1.

Benign lesions	Malignant/ aggressive lesions
Clearly defined boundaries	Boundaries are inaccurately defined or not defined
Extension or thinning cortical bone	Destruction of the adjacent part of the cortical bone
Periosteal reaction: absent or smooth	Periosteal reaction is uneven
Density: variable, often increased	Density: variable, often reduced
Teeth may be misaligned	Teeth “floating”, root resorption is possible

Table 1. Common radiological signs of proliferative lesions in the mandibular bone.

Examples are shown in Fig. 2.

Rice. 2a. Benign lesion of the second incisor of the left upper jaw. There was no loss of bone mass; mineralization was visualized in the area of ​​proliferation. There is no displacement of teeth.

Rice. 2b. Malignant lesion on the right side of the lower jaw. Resorption of bone tissue and tooth root, loss of the lamina durae dentis. The lesion is not clearly demarcated; a pathological fracture of the lower jaw is clearly visualized.

In the upper jaw, the tumor area is overlapped by nasal structures that hide its boundaries. Therefore, before attempting major surgery, advanced imaging studies such as CT or MRI are recommended (Figure 3).

Rice. 3a. X-ray. An area of ​​bone loss is identified between the upper right canine and the upper right second premolar. A space-occupying lesion displaces teeth. Caudal extension cannot be assessed due to overlap with nasal structures.

Rice. 3b. CT image (localization: canine root tip): a large lesion occupying a significant part of the right nasal cavity and causing a deviated nasal septum.

Rice. 3s. CT image (localization: 3rd premolar): the lesion occupies half of the right nasal meatus at the level of the 3rd premolar, with clear infiltration of bone tissue. This lesion is not visible on x-rays.

CT can detect differences in tissue density that are too subtle to detect on plain radiographs and may therefore also be useful for studying lesions of the mandible and tumor tissue invasion into the mandibular canal. In humans, conventional thin-slice (with a maximum slice thickness of 3 mm) CT has proven to be a highly sensitive and specific method for assessing mandibular canal invasion by squamous cell carcinoma. One veterinary study found that the size of the lesions and invasion of adjacent structures was more accurate in diagnosis on MRI, particularly in the more distal maxilla, and CT was found to be more helpful in visualizing areas of calcification and cortical bone erosion. For visualization of soft tissue lesions (tongue, soft palate, etc.) and assessment of tumor spread, MRI is the most suitable method.

In all cases of suspected malignant lesion, chest radiography is indicated (in the right lateral, left lateral and dorsoventral or ventrodorsal projections). Even if no pathology is detected on them, and there are no signs of metastasis, it should be borne in mind that space-occupying formations in the chest will be visible only if their diameter exceeds 0.5 cm, except in the case of multiple lesions.

3. Histopathological examination
Large lesions may be benign, but small lesions or non-healing ulcers may be highly malignant. The exact nature and grade of malignancy of the lesion can only be determined by histopathological examination. A representative biopsy should be performed (with tissue dissection for large or infiltrative lesions, excisional for small lesions without signs of bone infiltration). The value of fine needle aspiration in the diagnosis of space-occupying lesions of the oral cavity is usually limited. If the biopsy is performed atraumatically, within the boundaries of the excised lesion, the risk of developing metastases will not increase. If the lesion is not significantly mineralized, a disposable dermatome is usually used. The biopsy should be performed with care not to excise significantly inflamed or necrotic areas of the lesion, as these will complicate histopathological diagnosis; Biopsy of only the superficial layers of the skin, in which only reactive cells may be detected, should also be avoided.

A biopsy of regional lymph nodes (fine needle cytological aspiration or surgical biopsy) should also be performed. Surgical biopsy is the best method to confirm or exclude an infiltrative lesion, but requires more extensive tissue excision.

Clinical findings and histological findings should be consistent: a lesion that appears very aggressive is likely to be present, even if the histological findings do not confirm this. If discrepancies occur, the findings should be discussed with a clinical pathologist, and an additional biopsy is sometimes indicated.

4. Determination of the clinical stage of the disease
The clinical stage of the disease is determined based on the WHO TNM classification. This helps the doctor assess the condition of the tumor systematically and methodically, and the stage of the tumor is prognostically significant: it describes the clinical severity of the disease. The letter “T” denotes the primary tumor (size), N - damage to regional lymph nodes, M - the presence of metastases. The staging of oral tumors is presented in Table 2.

Stage I	T1N0, N1a or N2aM0	The primary tumor is less than 2 cm, normal lymphatic nodes, signs metastasis not found
Stage II	T2N0, N1a or N2aM0	Primary tumor 2 – 4 cm, normal lymph nodes, signs metastasis not found
Stage III	T 3N 0, N 1a or N 2a M 0 Any stage according to T N 1b M 0	The primary tumor is larger than 4 cm, normal lymphatic nodes, signs metastasis not found Or: primary tumor of any size, ipsilateral lymphatic nodes are affected, but not fixed to surrounding tissues, signs metastasis No
Stage IV	Any stage according to T N 2 b or N 3 M 0 Any stage according to T Any stage according to N M 1	Primary tumor of any size, contralateral lymphatic nodes are affected or fixed to surrounding tissues, there are no metastases Or: signs metastasis

Table 2. Staging of oral tumors.

The prognosis for stages I and II, depending on the histological type of tumor, is favorable, and after radical surgery the disease is often cured. In stage III, the prognosis largely depends on the histological type of the tumor (stage = grades, histological type = grades). Stage IV is accompanied by a poor prognosis.

Epulis
Epulis is a nonspecific growth of gum tissue. This clinical descriptive term covers a range of tumors and tumor-like gingival masses (Figure 4).

Rice. 4a. Epulis in the upper right canine. Smooth fibrous lesion with normal pigmentation. Histopathology: peripheral odontogenic fibroma (benign neoplasm).

Rice. 4b. Epulis between the first and second incisors of the upper jaw on the left. A loose, cauliflower-like mass that displaces teeth, bleeds on palpation, and infiltrates the bone. Histopathology: peripheral (acanthomatous) adamantinoma (locally aggressive lesion).

In half of the cases, epulis turns out to be a reactive lesion, and in about a fifth of cases, it is a locally aggressive or neoplastic lesion. Therefore, in cases of epulis, histopathological verification of the diagnosis should always be carried out.

Reactive tissue proliferation
1. Gingival hyperplasia / fibrous hyperplasia / inflammatory hyperplasia
Gingival hyperplasia can be focal, multiple focal or generalized. It occurs more often in dogs than in cats. Some breeds, such as Boxers, are particularly susceptible to this condition. Generalized hyperplasia may develop from accumulations of plaques; Hyperplasia is also caused by some drugs (diphenylhydantoin, cyclosporine, amlodipine) (Fig. 5).

Rice. 5. Generalized hyperplasia caused by cyclosporine in a West Highland White Terrier dog.

The lesions are composed of dense tissue and in some cases are accompanied by superficial pigmentation, ulceration and mineralization (Fig. 6).

Rice. 6a. Focal hyperplasia on the lingual side of the right mandibular first molar in a Labrador Retriever.

Rice. 6b. Generalized hyperplasia in a Labrador retriever. Most teeth are covered with epulis.

Clinically, gingival hyperplasia cannot be differentiated from a benign tumor lesion - peripheral odontogenic fibroma.

Treatment of epulis consists of marginal excision and removal of the original lesion (careful monitoring of the plaque, changing the drug if the lesion is medicinal).

2. Multiple epulis in cats (MFE)
This is a rare disease of young adult cats, with no sex or breed predisposition. In a sick cat, several large lesions appear on the gums, covering the crowns of most teeth (Fig. 7).

Rice. 7. Multiple epulis in a cat. Cure required gingivoplasty and extraction of the affected teeth.

Questions about the true nature and biological course of the disease have not been fully clarified. It has recently been reported that MFE is reactive in nature (gingival hyperplasia or peripheral osteogenic fibroma) and is most likely due to plaque accumulation in predisposed cats. Treatment involves marginal excision of the lesions (gingivoplasty) followed by careful monitoring of plaque formation. If a relapse is detected, recovery in most cases is achieved by removing teeth in the affected areas.

3. Other reactive lesions
Epulis may resemble other reactive lesions, such as peripheral giant cell granuloma, pyogenic granuloma, and peripheral osteogenic fibroma. These lesions are rare and isolated in nature. Treatment involves marginal excision of the lesions and elimination of the causative factor, if one can be identified.

Tumor lesions: odontogenic tumors
Odontogenic tumors are usually classified based on the origin of the tumor cells as epithelial, mesenchymal, or mixed. A different classification is sometimes used, based on the presence of induction, that is, interaction of cells of ectodermal and mesenchymal origin similar to that observed during normal dental development. In inductive odontogenic tumors, the cells form hard dental tissues that can be easily identified on x-rays.

Many odontogenic tumors present as epulis and may clinically resemble gingival hyperplasia.

1. Peripheral odontogenic fibroma
Peripheral odontogenic fibroma, also called periodontal ligament fibromatous epulis, is one of the most common odontogenic tumors in dogs. It has also been described by the terms "fibromatous epulis" and "ossifying epulis", but these terms should be used with caution as such proliferation should not be confused with fibrous tissue hyperplasia, with or without ossification.

Peripheral odontogenic fibroma is a benign growth originating from the periodontal ligament and is thus classified as a tumor of mesenchymal origin. It manifests itself as an epulis, fixed or pedunculated, with an intact or ulcerated surface. The lesion may be pigmented on the surface (Fig. 8).

Rice. 8. Peripheral odontogenic fibroma in a boxer. This dog also had generalized hyperplasia with epulis affecting a large number of teeth.

The main component of this tumor is fibroblast cell tissue. Various forms of dense tissue may form. In addition, varying numbers of strands of odontogenic epithelium are often present.

Treatment involves marginal tissue excision; if excision is inadequate, recurrences are common.

2. Ameloblastoma/Acanthomatous adamantinoma (“acanthomatous epulis”)
Adamantinoma is a neoplasm of epithelial tissue, such as enamel, that does not differentiate to the extent necessary to form enamel. It is one of the most common odontogenic tumors in dogs.

Ameloblastomas develop either in the gingival margin (peripheral ameloblastoma, manifesting as epulis) or from within the bone (central ameloblastoma). In advanced stages, these two types of lesions may be difficult to distinguish clinically. Some of the central ameloblastomas present as cystic lesions within the bone, suggesting that all cystic lesions in the oral cavity should be biopsied. Due to the similarity with a certain type of ameloblastoma in humans, it has been proposed to call this tumor “acanthomatous ameloblastoma”, without distinguishing between the peripheral and central types (Fig. 9).

Rice. 9. Acanthomatous ameloblastoma:

Rice. 9a. Peripheral localization.

Rice. 9b. Central localization.

Although biologically this tumor is benign and does not metastasize, locally it is extremely infiltrative and aggressive, causing extensive bone resorption, tooth displacement and even resorption of tooth roots (Fig. 10).

Rice. 10. Acanthomatous ameloblastoma (X-ray of the patient shown in Fig. 9b): extensive infiltration of bone tissue, with resorption of bones and tooth roots. This tumor is locally extremely aggressive.

The treatment of choice is extensive surgical excision.

Ameloblastoma is sensitive to radiation. Subsequent development of squamous cell carcinoma in irradiated areas after orthovoltage irradiation has been described, but megavoltage irradiation does not carry such a high risk.

3. Odontoma
An odontoma is a benign odontogenic neoplasm of mixed origin in which both epithelial and mesenchymal cells are fully differentiated so that tooth enamel and dentin are formed. Typically, such enamel and dentin are distributed in a pathological manner. Odontoma is usually detected in young animals, and it can develop in any part of the dental arch. Complex odontoma is a disorganized amorphous volumetric formation of hard dental tissues that has no resemblance to normal dental tissue. Mixed complex odontoma consists of several small tooth-like structures, the so-called “teeth” (Fig. 11).

Rice. 11. Odontoma (complex mixed odontoma). Large spreading lesion in the left maxilla, with multiple serration-like structures (teeth).

Both types of tumor are encapsulated and often associated with an unerupted tooth. They are benign in nature, but can cause tooth decay, and sometimes spread very actively.

The tumor has characteristic radiographic manifestations. A complex odontoma appears as an uneven space-occupying formation consisting of calcified material surrounded by a radiolucent rim. Mixed complex odontoma is a cluster of tooth-like structures, the number of which can vary.

Treatment consists of enucleation of the space-occupying lesion, and it is necessary to remove the entire capsule of the affected area. The treatment prognosis is favorable, and relapses are not expected.

4. Other odontogenic tumors
Other odontogenic tumors are sometimes observed.
Odontogenic amyloid-producing tumors are gingival masses that occur in both dogs and cats. This tumor is not thought to invade the bone, but causes bone erosion as it grows. Tumor metastasis has not been described. Treatment consists of complete resection.

Feline inductive odontogenic tumor is a rare lesion seen in young cats that occurs within the bone. Most often it forms on the rostral side of the upper jaw. This tumor causes significant tissue destruction and is not very clearly demarcated; it needs to be resected widely. Metastasis has not been described.

Tumor lesions: non-odontogenic tumors
1. Malignant melanoma (MM - Malignant Melanoma)
Malignant melanoma is considered the most common oral malignancy in dogs and accounts for 30–40% of all oral malignancies in this species, although squamous cell carcinoma is slightly more common in more recent studies.

In most reports, it was found to be significantly more common in males (male to female incidence ratio ranged from 2.5:1 to 4:1), but no sexual preference was described in a large review of MM. MM usually occurs in older dogs with some degree of oral pigmentation. Malignant melanoma is rare in cats, but its biological behavior in this species is the same as in dogs.

The most common localizations are the gums and mucous membranes of the lips/cheeks, but other localizations are also possible (on the palate, dorsum of the tongue).

In gingival lesions, teeth are often damaged and bone invasion is common (Figure 12).

Rice. 12a. Clinical picture. The color of MM can be from black to pink; often the proliferating tissue has a grayish appearance.

Rice. 12b. X-ray picture: the tumor deeply invades the underlying bone. Bone undergoes extensive resorption and concomitantly reactive new bone formation occurs. The lamina durae dentis of the fourth premolar and the medial aspect of the root of the first molar are not visible, and the teeth are surrounded by soft tissue. The tumor is not clearly demarcated and extends into the mandibular canal.

MM is a rapidly growing tumor, usually accompanied by ulceration and/or necrosis. Malignant melanoma can be pigmented or non-pigmented (amelanotic melanoma). Amelanotic melanoma is often difficult to diagnose and has an extremely aggressive course (Fig. 13).

Rice. 13. Pigmentless melanoma. This tumor is often accompanied by extensive necrosis because it grows so quickly that it encroaches on the vessels that feed it.

The prognosis is extremely unfavorable. Surgical excision of very small and early lesions can sometimes be successful, but for larger lesions, surgical treatment is no more than palliative, providing an improvement in the patient's quality of life. Most patients develop early metastases to regional lymph nodes and lungs. Median survival with aggressive surgical treatment, with or without radiation, is 5–9 months, and less than 25% of patients survive longer than a year. There is no optimal protocol for controlling or preventing the development of distant metastases.

Recently, a vaccine appeared on the market in the United States that, in a clinical trial, doubled survival rates. Other possible future treatments may target vascular endothelial growth factor (antiangiogenic therapy). Recently, oral MM cells in dogs were found to overexpress COX-2, suggesting that COX-2 inhibitors may be effective in the treatment of canine oral MM.

2. Squamous cell carcinoma (SCC - Squamous Cell Carcinoma)
SCC is diagnosed in 20–30% of canine oral tumors, although some recently released studies suggest that these canine oral tumors are now the most common. In cats, this is by far the most common type of oral tumor.

Oral squamous cell carcinoma in dogs
The most common site of SCC in dogs is the gums (Figure 14).

Rice. 14. Squamous cell carcinoma on the gum of the canine of the lower jaw on the right. The mass is friable, ulcerated, and bleeds on palpation.

The average age of affected dogs is 7–9 years, and there is no sex or breed preference for the tumor. Very young dogs (often less than 6 months old) develop a specific type of SCC, papillary SCC (Figure 15).

Rice. 15. Typical appearance of papillary squamous cell carcinoma in a 3.5-month-old German Shepherd. The lesion had been noticed a week earlier and had doubled in size within that time period.

The main space-occupying lesion often ulcerates. SCC may develop as a chronic non-healing ulcer without proliferation (Fig. 16).

Rice. 16. Extensive squamous cell carcinoma lesion in the upper jaw. The mass is not visualized, but extensive depigmentation, ulceration and loss of the palatine folds (rugae palatinae) are noted.

Teeth are often damaged, most lesions invade bone, and even tooth roots may be resorbed. The incidence of gingival SCC metastasis to regional lymph nodes and lungs is generally low, but increases with more caudal tumor location. SCC involving the tongue metastasizes more often.

The treatment of choice is extensive surgical excision (at least 1 cm of tumor margin). For more rostrally located SCC lesions, this is often sufficient to achieve cure (survival at one year reaches 85%).

Oral squamous cell carcinoma is a radiosensitive tumor, but surgical excision provides the best long-term prognosis. Radiation therapy is often given after surgery, especially for large tumors with a more caudal location, when a clean surgical margin of the tumor is not always easy to achieve. Other treatment options include pharmacotherapy (piroxicam plus carboplatin) and photodynamic therapy (for lesions less than one centimeter deep).

Due to the overexpression of COX-2 in SCC tumor cells in dogs, the administration of COX-2 inhibitory drugs (piroxicam, meloxicam) may be a useful adjunct to other treatments. In dogs with oral SCC, piroxicam has been shown to slow tumor progression in half of the cases. Thus, it may be effective as monotherapy if the owner refuses other treatments.
SCC of the tongue and tonsils is less common, but much more aggressive than the gingival form. The prognosis for tonsillar SCC is serious. Metastases to regional lymph nodes develop in the early stages of the disease, and at the time of diagnosis, metastases are detected in 90% of patients. Often, the primary mass formation remains undetected, and when contacting a veterinarian, large mass lesions are discovered in the neck area, which are actually metastatic lesions of the regional lymph nodes (Fig. 17).

Rice. 17. Squamous cell carcinoma of the tonsil in a dog:

Rice. 17a. The dog was diagnosed with a mass formation in the left neck area. Metastasis to the retropharyngeal lymph node was diagnosed.

Rice. 17b. Primary tumor in the left tonsil.

Oral squamous cell carcinoma in cats
In cats, SCC is the most common oral malignancy (60–70% of all oral malignancies). Oral SCC occurs most often in older cats, and no breed or sex preference has been identified for the tumor. The tumor is most often localized in the area of ​​the maxillary premolars/molars, mandibular premolars and tongue (Fig. 18).

Rice. 18. SCC of the lower jaw on the left in a cat. The tumor has infiltrated the entire left jaw and is expanding into the sublingual tissue. With such a widespread tumor, the prognosis is extremely unfavorable.

SCC readily infiltrates bone, and often the extent of bone invasion is significantly greater than expected from the clinical appearance of the lesion. Damage to the tongue can manifest itself as a non-healing ulcerative lesion of the frenulum, very similar to what develops when foreign bodies get under the tongue (Fig. 19).

Rice. 19. SCC of the tongue in a cat (initial stage of the lesion). Typical localization. This cat was treated with partial glossectomy and remains alive 8 years after surgery.

Often the tumor is not visible, but can be palpated as a solid mass in the ventral part of the tongue of the caudal frenulum (Fig. 20).

Rice. 20. SCC of the tongue in a cat (late stage of lesion). An ulceration is visualized on the ventral surface of the tongue, but the mass is mainly palpated in the ventral part of the body of the tongue caudal to the frenulum.

The high incidence of SCC in cats has prompted research into the possible causes of this phenomenon. The development of SCC in cats, given their inherent licking habit, may be facilitated by exposure to carcinogens such as flea collars and topical anti-tick and anti-flea medications. Chronic inflammation may be important, and the incidence of SCC is thought to be increased in cats with chronic stomatitis.

The best treatment option for SCC in cats is considered to be complete surgical excision of early lesions, although even with extensive surgery, survival for SCC is significantly lower than for fibrosarcoma and osteosarcoma. The prognosis for SCC of the maxilla and tongue is poor because the tumor rarely responds to any type of therapy. Median survival for SCC is one and a half to two months, and less than 10% of patients survive longer than a year.

There are currently no effective methods of drug therapy for the tumor. Although feline oral SCC has been shown to actively express COX-1 and COX-2, the effect of COX-2 inhibitors is unpredictable. Future treatment options may include epidermal growth factor inhibitors or drugs such as zoledronate (a bisphosphonate) that slow tumor growth.

SCC in cats is poorly sensitive to radiation. Radiation therapy is used as palliative treatment in combination with the prescription of radiosensitizers; survival does not increase, but quality of life improves.

3. Fibrosarcoma
Fibrosarcoma is rare in dogs, but in cats it is the second most common of the oral tumors. Fibrosarcoma is most often detected in large breed dogs, on average at an earlier age than MM and SCC (about 7 years), and in small breeds it develops at an older age (> 8 years). Fibrosarcoma is most often localized in the upper jaw. It can develop in the form of a volumetric formation protruding beyond the edge of the teeth and palate (Fig. 21).

Rice. 21. Fibrosarcoma in a dog, manifested by a protruding mass formation on the palate, with an intact epithelial lining.

Fibrosarcomas can also arise from the nasal cartilage, lateral surface of the maxilla, or palate, and appear as a homogeneous mass with an intact epithelial lining.

Radiologically, fibrosarcoma is characterized by extensive bone resorption (Fig. 22).

Rice. 22. Fibrosarcoma of the lower jaw in a dog; clinical and radiographic manifestations:

Rice. 22a. Clinical picture

Rice. 22b. X-ray picture: widespread bone destruction by tumor, without clear delineation.

A CT scan is strongly recommended because x-rays will greatly underestimate the extent of the lesion. Regional lymph nodes are rarely affected, but metastasis to the lungs occurs in approximately 20% of cases.

A specific type of tumor, “fibrosarcoma of histologically low and biologically high grade,” develops in relatively young dogs; Moreover, a predisposition has been identified in golden retrievers. While biopsy reveals a tumor of low histological grade (fibroma or well-differentiated fibrosarcoma), this tumor grows invasively and resembles aggressive fibromatosis in humans. Fibromatosis is a lesion in the head and neck area that develops in young adults and has a high rate of recurrence after surgical treatment.

Surgical treatment of fibrosarcoma does not always achieve a cure, and relapses after wide or radical resection are observed in more than half of the cases. The one-year survival rate after surgery alone is 40–45%. The combination of surgery and radiation therapy provides much better survival rates.

4. Osteosarcoma
Osteosarcoma of the oral cavity develops mainly in dogs of medium and large breeds and, as a rule, in middle or older age (the average age of animals is about 9 years) (Fig. 23 and 24).

Rice. 23. Osteosarcoma on the upper jaw in an American Staffordshire Terrier.

Rice. 24. Osteosarcoma: radiographic picture in a boxer. There is massive bone destruction and the formation of new bone tissue. The extent of the tumor cannot be assessed from x-rays; A CT scan is strongly recommended.

Osteosarcoma is more common in the lower jaw and less common in the upper jaw. The incidence of metastasis of osteosarcoma of the oral cavity is lower than that of osteosarcoma of the appendicular skeleton, and the survival rate is higher (according to various sources, the overall one-year survival rate ranges from 26 to 60%). The prognosis worsens with increasing histological grade and increasing alkaline phosphatase levels.

Treatment consists of radical surgical excision, preferably in combination with adjuvant therapy (chemotherapy, radiation therapy, NSAIDs). Promising results have been obtained with the recently proposed treatment with bisphosphonates, which can provide a palliative effect (reduction of bone resorption, reduction of bone pain) and have a direct antitumor effect.

5. Other tumors
Many other tumors develop in and around the mouth. Some examples:

Oral papillomatosis observed in rare cases, most often in young dogs (Fig. 25).

Rice. 25. Oral papillomatosis in a 6-month-old American cocker spaniel.

The lesions are usually self-limiting and will regress without treatment within 4 to 8 weeks.

Mast cell tumor may develop in the area of ​​the lip border or on the mucous membrane of the lips or oral cavity. The biological behavior of the tumor is identical to the behavior of this tumor in other locations.

Extramedullary plasmacytoma can also develop in the oral cavity. There was no clear correlation with myeloma; complete surgical removal may be curative.

Epitheliotropic T-cell lymphoma may manifest as lesions in the oral cavity (Fig. 26).

Rice. 26. Epitheliotropic T-cell lymphoma:

Rice. 26a. Clinical manifestations include depigmentation and ulceration of the oral cavity.

Rice. 26b. Clinical manifestations in the form of obvious proliferative lesions.

Usually the first clinical sign of the disease is depigmentation of the oral mucosa, accompanied by or without ulceration. Sometimes areas of true proliferation are visible. In most cases, the skin is also affected. The prognosis is unfavorable.

When treating rarer tumors, literature on the biological behavior of these tumors in humans or other sites in the body should be used to guide treatment selection (eg, excision margins) and prognosis. It is necessary to accumulate more detailed information on the behavior of less common tumors, since at present there are only anecdotal reports. Any suspicious lesions in the oral cavity should be biopsied and histopathologically examined by a concerned and sufficiently experienced pathologist. It is necessary to ensure long-term observation of the patient and describe this observation.

Surgical treatment of proliferative lesions of the oral cavity
There are a number of treatment options, including surgery, radiation therapy, chemotherapy, hyperthermia, photodynamic therapy, and vaccination.

For most oral tumors, surgery remains the most important component of the treatment regimen, although adjuvant therapy is often indicated. When choosing the best treatment option for each patient, it is important to ensure close collaboration between the surgeon and oncologist.

In most cases, surgical treatment is performed with the goal of achieving a cure. However, this is not always possible to achieve due to the extent of the lesion, and in some cases surgery is performed palliatively, or for the purpose of cytoreduction, before radiation therapy, chemotherapy or other types of adjuvant therapy.

Infiltrative tumors of the lower jaw require wide excision or treatment with radical surgery, which requires removing part of the upper or lower jaw along with the tumor. The functional and cosmetic results of these interventions are usually very favorable (Figs. 27 and 28).

Rice. 27. Appearance after mandibulectomy:

Rice. 27a. Close-up view of the mandible - the mandible on the left is removed from the first incisor to the area distal to the second premolar.

Rice. 27b. Cosmetic appearance.

Rice. 28. Appearance after maxillectomy:

Rice. 28a. Close-up view of the mandible - the left maxilla is removed from the area distal to the first premolar to the area distal to the fourth premolar. The resection extended almost to the midline, including the infraorbital canal.

Rice. 28b. Cosmetic appearance

Cats tolerate major surgeries worse than dogs. Surgical treatment of oral tumors should ideally be performed by an experienced (oral) surgeon, and a description of surgical treatments is beyond the scope of this article.

Bibliography:
1. Vos JH, van der Gaag I, van Sluys J. Oropharyngeale tumoren bijhond en kat: een overzicht. Tijdschr.Diergeneesk. 112, 251-263, 1987.
2. Hoyt R F, Withrow SJ. Oral malignancy in the dog. J Am Anim Hosp Assoc 20, 83-92, 1982.
3. Oakes MG, Lewis DD, Hedlund CS, Hosgood G. Canine oral neoplasia. Comp Cont Ed Pract Vet 15, 15-29, 1993.
4. Stebbins KE, Morse CC, Goldschmidt MH. Feline Oral Neoplasia: A Ten-Year Survey. Ve t Pathol 26, 121-128, 1989.
5. Harvey CE, Emily PE. Oral Neoplasms. In: Small Animal Dentistry. St. Louis: Mosby Year Book: 297-311, 1993.
6. Verstraete FJM. Mandibulcetomy and Maxillectomy. Vet Clin Small Anim 35, 1009-
1039, 2005.
7. Regezi JA, Sciubba J. Ulcerative conditions: Neoplasms. In: Oral Pathology: Clinical-Pathologic correlations. Philadelphia: WB Saunders:77-90, 1993.
8. White RAS. Tumors of the Oropharynx. In: BSAVA Manual of Canine and Feline Oncology, 2nd ed, Dobson JM and Lascelles BDX eds. Gloucester: BSAVA publications: 206-213, 2003.
9. Dennis R. Imaging Tumors. In: BSAVA Manual of Canine and Feline Oncology, 2nd ed, Dobson JM and Lascelles BDX eds. Gloucester: BSAVA publications: 41-60, 2003.
10. Mukherji SK et al. CT detection of mandibular invasion by squamous cell carcinoma in the oral cavity. Am J Roentgenol 177, 237-43, 2001.
11. Imaizumi A et al. A potential pitfall of MR imaging for assessing mandibular invasion of squamous cell carcinoma in the oral cavity. Am J Neuroradiol 27, 114-22, 2006.
12. Kafka et al. Diagnostic value of magnetic resonance imaging and computed tomography for oral masses in dogs. J SAfr Vet Ass 75, 163-168, 2004.
13. White RAS. Core, incisional and excisional biopsy. In: BSAVA Manual of Canine and Feline Oncology, 2nd ed, Dobson JM and Lascelles BDX eds. Gloucester: BSAVA publications: 38-40, 2003.
14. Smith MM. Surgical approach for lymph node staging of oral and maxillofacial neoplasms in dogs. J Am Anim Hosp Assoc 31, 514-518, 1995.
15. Withrow SJ, Lowes N. Biopsy techniques for use in small animal oncology. J Am An Hosp Assoc 17, 889-902, 1981.
16. White RAS, Jefferies AR, Freedman LS. Clinical staging for oropharyngeal malignancies in the dog. J Small Anim Pract 26, 581-594, 1985.
17. Carranza FA., Hogan EL. Gingival Enlargement. In: Newman MG, Takei HH., Carranza FA (editors) Carranza’s Clinical Periodontology, 9th edition Saunders, Philadelphia p 279-296, 2002.
18. Verstraete FJM, Ligthelm AJ, Weber A. The histological nature of Epulides in Dogs. J. Comp. Path. 106, 169-182, 1992.
19. Verhaert L. Retrospectieve Review of Oral Proliferative Lesions seen in a Small Animal Practice 1993-2005, Proceedings 19th Annual Veterinary Dental Forum and World Veterinary Dental Congress, 2005.
20. Harvey CE, Emily PE. Periodontal Disease. In: Small Animal Dentistry. St. Louis: Mosby Year Book: 104, 1993.
21. Nam HS., McAnulty JF., Kwak HH., Yoon BI., Hyun C., Kim WH., Woo HM. Gingival Overgrowth in Dogs Associated with Clinically Relevant Cyclosporine BloodLevels: Observations in a Canine Renal Transplantation Model. Veterinary Surgery 37,247-253, 2008.
22. Thomason JD, Fallaw TL, Carmichael K P, Radlinsky MA, Calvert CA. Gingival hyperplasia associated with the administration of amlodipine to dogs with degenerative valvular disease (2004-2008). Journal Veterinary Internal Medicine 23, 39-42, 2009.
23. Knaake FAC, Verhaert L. Histopathology and treatment of nine cats with multiple epulides. Vlaams Diergeneeskundig Tijdschrift 79, 48-53, 2010.
24. Regezi JA, Sciubba J. Odontogenic tumors. In: Oral Pathology: Clinical-Pathologic
correlations. Philadelphia: WB Saunders: 362-397, 1993.
25. Verstraete FJM. Oral Pathology. In: Textbook of Small Animal Surgery, 3rd ed. Slatter D, ed. Philadelphia: WB Saunders: 2638-2651, 2003.
26. Gardner DG. Odontogenic Tumors in Animals, with Emphasis on Dogs and Cats. Proceedings of the 11th European Veterinary Dental Congress, 16-27, 2002.
27. Gardner DG, Baker DC. The relationship of the canine acantomatous epulis to ameloblastoma. J Comp Path 108, 47-55, 1993.
28. Thrall DE, Goldschmidt MH, Biery DN. Malignant tumor transformation at the site of previously irradiated acantomatous epulides in four dogs. J Am Vet Med Assos 178, 127-132, 1981.
29. McEntee MC, Page RL, Théon A, Erb HN, Thrall DE. Malignant tumor formation in dogs previously irradiated for acantomatous epulis. Vet Radiology and Ultrasound, 45, 357-361, 2004.
30. Bronden LB, Eriksen T, Kristensen AT. Oral malignant melanomas and other head and
neck neoplasms in Danish dogs – data from the Danish Veterinary Cancer Registry. Acta Veterinaria Scandinavica 51, 54, 2009.
31. Ramos-Vara JA, Beissenherz ME, Miller MA, Johnson GC, Pace LW, Kottler SJ. Retrospective study of 338 canine oral melanomas with clinical, histologic and immunohistochemical review of 129 cases. Vet Pathol 37, 597-608, 2000. Harvey HJ, MacEwen EG, Braun D, ​​Patnaik AK, Withrow SJ, Jongeward S. Prognostic criteria for dogs with oral melanoma. J Am Vet Med Assoc 178, 580-582, 1981.
33. Bergman PJ, McKnight J, Novosad A, Charney S, Farrelly J, Craft D, Wulderk M, Jeffers Y, Sadelain M, Hohenhaus AE, Segal N, Gregor P, Engelhorn M, Riviere I, Houghton AN, Wolchok JD. Long-term survival of dogs with advanced malignant melanoma after DNA vaccination with xenogeneic human tyrosinase: a phase I trial. Clin Cancer Res 9,1284-90, 2003.
34. No authors listed. USDA licenses DNA vaccine for treatment of melanoma in dogs. J Am Vet Med Assoc 236, 495, 2010.
35. Taylor KH, Smith AN, Higginbotham M, Schwartz DD, Carpenter DM, Whitley EM.
Expression of vascular endothelial growth factor in canine oral malignant melanoma. Vet Comp Oncol 5, 208-218, 2007.
36. Pires I, Garcia A, Prada J, Queiroga FL. COX-1 and COX-2 expression in canine cutaneous, oral and ocular melanocytic tumors. J Comp Path 143, 142-149, 2010.
37. Postorino Reeves NC, Turrel JM, Withrow SJ. Oral squamous cell carcinoma in the cat. J Am Anim Hosp Ass 29, 438-441, 1993.
38. Ogilvie GK, Sundberg JP, O'Bannion K. Papillary squamous cell carcinoma in three young dogs. J Am Vet Med Assoc 192, 933-935, 1988.
39. Stapleton BL, Barrus JM. Papillary squamous cell carcinoma in a young dog. J Vet Dent 13, 65-68, 1996.
40. Carpenter LG et al. Squamous cell carcinoma of the tongue in 10 dogs. J Am Anim Hosp Ass 29(1), 17-24, 1993.
41. de Vos J P, Burm AG, Focker A P, Boschloo H, Karsijns M, van der Waal I. Piroxicam and carboplatin as a combination treatment of canine oral non-tonsillar squamous cell carcinoma: a pilot study and a literature review of a canine model of human head and neck squamous cell carcinoma. Vet Comp Oncol 3, 16-24, 2005.
42. McCaw DL, Pope ER, Payne JT, West MK, Tompson R V, Tate D. Treatment of canine oral squamous cell carcinomas with photodynamic therapy. Br J of Cancer 82, 1297-1299, 2000.
43. Schmidt BR, Glickman N W, DeNicola DB, de Gortari AE, Knapp DW. Evaluation of piroxicam for the treatment of oral squamous cell carcinoma in dogs. J Am Vet Med Assoc 218, 1783-1786, 2001.
44. Withrow SJ. Tumors of the gastrointestinal system. In: Small animal clinical oncology, 2nd ed, Whitrow SJ, MacEwen EG eds. W. B. Saunders, Philadelphia, 227-240, 1996.
45. Bertone ER, Snyder LA, Moore AS.
Environmental and lifestyle risk factors for oral squamous cell carcinoma in domestic cats. J Vet Intern Med 17, 557-562, 2003.
46. ​​Northrup NC, Selting KA, Rassnick KM, Kristal O, O'Brien MG, Dank G, Dhaliwal RS, Jagannatha S, Cornell KK, Gieger TL. Outcomes of cats with oral tumors treated with mandibulectomy: 42 cases. J Am Anim Hosp Assoc 42, 350-360, 2006.
47. Hayes AM, Adams VJ, Scase TJ, Murphy S. Survival of 54 cats with oral squamous cell carcinoma in United Kingdom general practice. J Small Anim Pract 48, 394-3999, 2007.
48. Hayes A, Scase T, Miller J, Murphy S, Sparkes A, Adams V. COX-1 and COX-2 expression in feline oral squamous cell carcinoma. J Comp Pathol 135, 93-99, 2006.
49. Looper JS, Malarkey DE, Ruslander D, Proulx D, Thrall DE. Epidermal growth factor receptor expression in feline oral squamous cell carcinomas. Ve t Comp Oncol 4, 33-40, 2006.
50. Wypij JM, Fan TM, Frederickson RL, Barger AM, de Lorimier L P, Charney SC. In vivo and in vitro efficacy of zoledronate for treating oral squamous cell carcinoma in cats. J Vet Intern Med 22, 158-163, 2008.
51. Jones PD, de Lorimier L P, Kitchell BE, Losonsky JM. Gemcitabine as a radiosensitizer for nonresectable feline oral squamous cell carcinoma. J Am Anim Hops Assoc 39, 463-467, 2003.
52. Ciekot PA, Powers BE, Withrow SJ, Straw RC, Ogilvie GK, LaRue SM. Histologically low-grade, yet biologically high-grade, fibrosarcomas of the mandible and maxilla in dogs: 25 cases (1982-1991) J Am Vet Med Assoc 204, 610-615, 1994.
53. Hammer AS, Weeren FR, Weisbrode SE, Padgett SL. Prognostic factors with osteosarcomas in the flat or irregular bones. J Am Anim Hosp Assoc 31, 321-326, 1995.
54. Straw RC, Powers BE, Klausner J, Henderson RA, Morrison WB, McCaw DL, Harvey
HJ, Jacobs RM, Berg RJ. Canine mandibular osteosarcoma: 51 cases (1980-1992). J Am Anim
Hosp Assoc 32, 257-262, 1996.
55. Kirpensteijn J, Kik M, Rutteman GR, Teske E. Prognostic significance of a new histologic grading system for canine osteosarcoma. Vet Pathol 39, 240-246, 2002.
56. Farese J P, Ashton J, Milner R, ambrose LL, Van Gilder J. The effect of the biphosphanate alendronate on the viability of canine osteosarcoma cells in vitro. In Vitro Cell Dev Biol Anim, 113-117, 2004.
57. Fan TM, de Lorimier L P, Garrett LD, Lacoste HI. The bone biological effects of zoledronate in healthy dogs and dogs with malignant osteolysis. J Vet Intern Med 22, 380-387, 2008.
58. Spugnini E P, Vincenzi B, Caruso G, Baldi A, Citro G, Santini D, Tonini D. Zoledronic acid for the treatment of appendicular osteosarcoma in a dog. J Small Anim Pract 50, 44-46, 2009.

Leen Verhaert,
DVM, EVDC Diploma.
Ghent University, Faculty of Veterinary Medicine,
Department of Medicine and Clinical Biology of Small Animals (Belgium)