Urolithiasis in dogs: signs and treatment. Bladder stones in dogs: causes, types, symptoms and treatment

The formation of stones in the urinary tract is possible in dogs of different breeds and of any age, but older animals suffering from metabolic disorders are most susceptible to the disease. Just like in humans, this disease can have various causes in dogs.

Stone formation in the urinary tract, or urolithiasis, has some peculiarities in dogs. Unlike humans, dogs are more likely to develop calculi (stones) in the bladder or ureters than in the kidneys. Kidney damage occurs in about 10% of all cases. The remaining number of diseases is dominated by stones in the bladder and urethra (urethra).

Causes of the disease

There are several types of stones that occur as a result of urolithiasis in dogs:

1. Struvite. They are the most common - up to 70% of cases.
2. Oxalates - up to 20% of diseases. This type of stone is considered one of the most dangerous, since even ultrasound and laser can’t handle them well.
3. Urats. These stones are less common than others.
4. Cystines.
5. Xanthines.
6. Concretions of mixed type.

The reasons why urolithiasis appears are diverse and are divided into external and internal. External reasons are related to the animal’s nutrition: the composition of the water that is given to the dog, the level of its mineralization, food, its composition, the level of salinity, the predominance of protein, and so on.

Internal causes are disruptions in the normal functioning of the organs and systems of the dog’s body, that is, metabolic disorders, inflammatory processes in the genitourinary tract, genetic pathologies, problems with the functions of the parathyroid glands and other hormonal disorders, portacaval shunt, and so on.

The development of stone formation in a dog can be caused by the owner’s neglect of the animal’s needs, for example, an insufficient amount of water, due to which the animal suffers from dehydration, regular bladder overflow due to untimely walking of the dog, kidney disease that occurs due to hypothermia if the pet sleeps on cold floor, in drafts, in an uninsulated booth outside the house.

Short-haired animals and “hairless” dogs should be walked in cold weather wearing special warm blankets or overalls to protect their kidneys. Any cold can cause kidney dysfunction, and this already becomes a reason for the development of inflammation and the beginning of the formation of stones.

Which breeds are more susceptible

Different breeds tend to develop different types of urinary stones:

1. Struvite stones, while most common, occur in middle-aged dogs (4–6 years old). Miniature schnauzers, beagles, Scotch terriers, dachshunds, poodles and Pekingese are more susceptible to the formation of this type of stones. It is interesting that stones of this type occur more often in females than in males, they are accompanied by infection, and the urine has an alkaline reaction.
2. Oxalate stones are more likely to form in older dogs - 7–8 years old, more often in males than in females. The most susceptible are miniature schnauzers, Yorkshire terriers, “chrysanthemum dogs” Shih Tzu, and Lhasa Apso. The inflammatory process is rare, the urine reaction is acidic.
3. Urate stones most often plague Dalmatians suffering from a genetic disorder of purine metabolism. Young animals get sick, but in principle they can be of any age. Young dogs with portal blood flow disorders - miniature schnauzers, Irish wolfhounds, Yorkshire terriers, Maltese dogs, Australian shepherds and Cairn terriers - under 12 months of age are also prone to urate formation. Males with acidic urine are more susceptible to the disease.
4. Cystine stones occur with cystinuria; stone formation is not always observed; males aged 1.5 to 5 years are affected. At risk are Chihuahuas, English bulldogs, Irish terriers, dachshunds, and Yorkshire terriers. The urine reaction is most often acidic.

It cannot be said that there are dog breeds that are not prone to developing urolithiasis. It can appear in certain circumstances in dogs of any breed and age.

Main symptoms

The most common signs of the disease include the following:

1. Frequent urination. The dog not only begins to ask to go out very often, but can also “make a puddle,” even if this is an adult animal and nothing like this has ever been noticed before.
2. Pain during urine excretion. The dog squeals and whines while urinating, after which it takes a long time to come to his senses, does not want to play, run, tries to lie down and even hide away from people.
3. The appearance of traces of blood, sand or pus in the urine if the disease is accompanied by an acute inflammatory process.
4. Obstruction of the urinary tract, which can lead to intoxication and kidney failure.
5. Signs of hepatic encephalopathy in dogs with portacaval shunts.
6. The animal reacts painfully to touching the kidney part of the back and the lower half of the abdomen. In an acute condition, it can growl and can even bite the owner if he accidentally causes pain.

If the stones are in the kidneys or at the top of the ureters without blocking them, they can go undetected for a long time. The disease does not show itself in any way, and at this time chronic disease develops.

Diagnostics in a veterinary clinic

If a dog shows signs of urolithiasis, or there is a suspicion of it, it is necessary to undergo the following examinations and tests at a veterinary clinic:

1. Ultrasound of the abdominal cavity.
2. Radiography to identify stones with radiopaque capabilities.
3. Excretory urography or cystography with double contrast if there is uncertainty when making a diagnosis.
4. General and biochemical blood test.
5. General urine analysis.
6. Bacterial culture of urine.

After removing the stones, it is necessary to examine them.

Treatment method and prognosis

The method of treating the disease depends on the condition of the animal and whether there is strangulation of the ureter or urethra by stones. If possible, the veterinarian chooses drug therapy. For this purpose, drugs and manipulations are used to crush and dissolve stones, as well as anti-inflammatory and painkillers, and other medications necessary to treat the disease and eliminate symptoms.

The stone stuck in the urethra is pushed back into the bladder, catheterization is performed with a special thin catheter, urethrotomy (dissection of the urethra to remove the stone) or urethrostomy (formation of a stoma from a wide part of the urethra, that is, removal of the urethra into the perineum between the scrotum and anus).

Stones returned from the urethra to the bladder or formed in it from the ureter are removed surgically using cystostomy, that is, opening the bladder.

Oxalate stones require a special approach. They are not dissolved by special preparations and influences, and they also have a special structure. If they form in the kidneys, they take the shape of the renal pelvis and can completely block the organ, which leads to its death. This threatens not only the health, but also the life of the dog.

What to do at home

Treatment of urolithiasis is long and quite complex. If an animal is scheduled for surgery, it will be under observation in the clinic for the first time. When the veterinarians are sure that everything is fine with the dog, she will be released home. At home, the animal is provided with complete rest, warmth, proper nutrition, following a special diet prescribed by a veterinarian for a specific type of stone.

If there is an inflammatory process or in the postoperative period, the dog is prescribed a course of antibiotic therapy. Treatment of the disease is long-term, up to several months, and in case of chronic urolithiasis with kidney damage - lifelong.

After bougienage, ultrasonic crushing of stones or surgery, the animal must be regularly brought for checks to the veterinary clinic in order to ensure positive results of treatment and prevent relapse of the disease.

At home, the most important thing for a dog is diet and sufficient, but not excessive, clean drinking water, as well as protection from hypothermia and infections.

If struvite is present, diets restricting protein, calcium, magnesium and phosphorus are used. With urates, the amount of proteins and purines in food is reduced. Cystine stones also reduce the volume of proteins. Oxalate stones require the elimination of hypercalcemia if the veterinarian has concluded that such a problem exists.

Possible complications

The presence of urolithiasis threatens with various complications depending on where the stones are located. If stones block the ureter or urethra, this leads to an acute attack with severe pain. If the stone has sharp edges, it may damage the walls of the urethra or ureter. In this case, only urgent hospitalization and surgical intervention can save the animal’s life.

Kidney stones are a potential threat for the development of many diseases: from chronic renal failure, nephritis and pyelonephritis, inflammation of the renal pelvis to complete kidney failure.

If an infection is associated with urolithiasis, it can spread through the bloodstream throughout the dog’s body and cause serious harm to the health of many organs, including the heart. If the course of the disease is extremely unfavorable, the dog is at risk of sepsis - a general blood infection.

Prevention measures

The main measure to prevent the development of urolithiasis is to follow a proper balanced diet designed for the age of the animal. You cannot feed your dog from your table, much less give it salty food, smoked meats, marinades, pickles and sweets, and baked goods.

Unnatural food leads to the development of many diseases, including obesity, diabetes, problems with joints and blood vessels, and the formation of kidney stones.

The dog needs to be protected from colds, since hypothermia promotes the inflammatory process in the kidneys and in the genitourinary system as a whole. This provokes numerous problems, including the possibility of becoming a trigger for stone formation.

You cannot force a dog to “endure” for a long time; you need to take it outside regularly, at least twice a day. An overfilled bladder also leads to inflammation and the formation of stones.

Proper nutrition, a healthy lifestyle and attentive attitude of the owners will help maintain good health for any pet, regardless of its age and breed.

One of the aspects in drug therapy for KSD in animals is the removal of uroliths and the creation of conditions that lead to their dissolution. Pharmacological treatment is important, but in some cases, DobroVet VC specialists have to resort to modern, radical methods ().

Drug therapy

The principle of dissolving stones is the undersaturation of urine with mineral components, in other words, not giving the stone enough “nutrition” for growth. This leads to their reverse development - the transition of stone (sand) from a solid state to urine.

Timely administration of pharmaceuticals will change the chemical composition of the animal’s urine and prevent the formation of stones and sand in the bladder, thereby preventing the appearance of urolithiasis. In the kidneys, if the functioning of the organ is adequate, kidney stones can be dissolved. But this takes more time.

Important. Stones in the urethra and ureter cannot be dissolved without moving them back into the bladder.

The duration of dissolution in the bladder is from 2 to 4 months, it is important for the pet owner to remember this and not stop taking the medications until the attending physician stops them. The therapy required for dissolution is prescribed depending on the type of urinary stone, which is determined based on urine analysis and clinical data. It is not recommended to treat UCD at random without tests; in this case, the urinary calculus does not dissolve, or only part of it dissolves.

If drug therapy has not brought results after 2 months, if the animal is experiencing severe pain, bleeding has started, or there is a blockage of the ureter or urethra, urgent surgical intervention is indicated .

The decision to carry out a particular treatment method is made by the veterinarian at the DobroVet Center during the initial examination of the animal, and it is always strictly individual. VC DobroVet specialists do not recommend self-treating your pet with the same medications that helped the “cat next door.” There is a high risk of improper therapy, which can be fatal.

Dissolution of struvite uroliths

When dissolving struvite uroliths that formed secondary to a urea-splitting infection, constant control over the infection and a decrease in the concentrations of magnesium, ammonium, and phosphate in the urine will be required.

Prescribed drugs that “shift” the pH of urine to the acidic side and antimicrobial agents that suppress infection. Special diets are also shown that reduce the concentration of the mineral components of struvite (dry food S/D, Prescription Diets, Hill's Pet Products). Dry food contains a low percentage of protein, phosphorus, magnesium and calcium. Diets often involve a higher salt content to increase thirst and excretion of less concentrated urine.

Contraindications for diets can be any disease in animals in which the percentage of salt should not be increased (hypertension, edema, liver and heart failure, hypoalbuminemia). For pets with kidney problems, the new diet should be introduced slowly (several weeks) to ensure there is no hypertension.

Important. When using such diets, special additives that acidify urine are not used. The diet should continue 2-4 weeks after the stones disappear. Each type of animal needs to be fed the appropriate food, depending on its nutritional needs. Diets are unacceptable for young cats and dogs (growing, up to a year).

"Sterile" struvite

If sterile uroliths are detected, a diet (or drugs) that acidify urine is prescribed; S\D food is used for dogs and cats. In dogs, “sterile” struvite disappears after about 6 weeks (1-3 months), in cats on average 5 weeks (2-20 weeks).

Urats

Prescribed drugs that alkalinize the urine and reduce the formation of uric acid. The duration of taking the drugs is from 2 to 4 months. It is important for the pet owner to remember this and not to stop taking medications prescribed by the doctor earlier than prescribed. It is recommended to extend therapy for another month after visual diagnosis of the disappearance of urates.

As a rule, these recommendations apply only to dogs; for cats, the recommended method of removing urate stones is surgery. Changing the diet has a clear goal - reducing the consumption of uric acid (which is found in the kidneys, liver), dry food according to the U\D diet (produces more alkaline urine) or S\D (acidify the urine, but contain salt to increase urine output). Unfortunately, the ideal dry diet has not been developed.

Cystine formations

For cystine stones, medications are prescribed that reduce the formation of cystine and alkalinize the urine. It will take 2-4 months for the stones to dissolve; drug therapy is combined with diet.

Prevention of urolithiasis during natural feeding

For prevention, it is important to consider the causes that contribute to the occurrence of ICD:

• - quantity and quality of food. Natural feeding with overeating contributes to the alkalization of urine. When feeding 5-7 times a day, the animal’s urine becomes constantly alkaline (after eating, the urine shifts to the alkaline side for 2-4 hours). Lack of Ca leads to disruption of mineral metabolism and promotes the formation of phosphate stones;
• - quality and quantity. Raw tap water contains many soluble salts, which increase mineral imbalances. It is advisable to use soft bottled water;
• - sedentary lifestyle;
• - rare urination. Associated with low water consumption;
• - genetics. In this case, only prevention will help your pet.

Modern methods of treatment

VC DobroVet offers quick and radical methods for removing stones from the kidneys and bladder of animals. Ultrawave lithotripsy is a method of crushing urinary formations using new, cutting-edge equipment that sends focused shock wave pulses to a given point. This allows you to quickly and effectively remove stones from an animal with uncomplicated forms of urolithiasis.

Removing urinary stones: methods

The DobroVet VC offers to remove urinary stones from animals in the following ways:

1. Laser crushing (using a holmium laser).
2. Ultrasonic crushing of stones.
3. Laparoscopically assisted cystotomy.
4. Standard cystotomy.

Which method will be applied to a particular animal is up to the specialist to decide. This depends on the results of the examination, the type of stones, their quantity, the presence/absence of infection in the urinary tract, the threat of urethral rupture, etc.

The course and number of procedures is determined strictly individually for each pet!

Questions for the veterinarian

How long does it take to treat struvitis with infection?

In dogs, struvite stones burdened with infection dissolve on average in 2-7 months. This type of struvite is rare in cats, but it takes longer to dissolve - 9-13 weeks.

What is the purpose of changing your diet?

The goal of changing the diet is acidic urine (pH-6.0), which creates unfavorable conditions for stones and bacteria.

Which popular “truths” about the ICD are misconceptions?

There are two of them:

Feeding cats fish has nothing to do with the occurrence of urolithiasis and the development of stones;

Castration of cats does not affect the occurrence of urolithiasis, except that sterilized animals move less.

Veterinary center "DobroVet"

Unfortunately, few breeders will closely look at how the act of urination occurs in their pet. By the course of the act of urination in an animal, you can tell a lot about its health. For example, this way you can identify stones in a dog’s bladder in a timely manner, without waiting until the uroliths do something serious to the genitourinary system. And the consequences of this pathology, by the way, can be extremely serious. Even cases of death are not so rare.

By the way, where from? After all, anatomically, the presence of these neoplasms in a dog’s body is not provided for in any way! It's simple. Today it is believed that leads to the formation of uroliths increased concentration in the urine of substances that can precipitate due to a combination of some special factors. As a rule, this happens when basic norms and animals are violated: for example, in dogs that have spent their entire lives on a diet of dry food, the development of uroliths is a very likely outcome.

It all starts with the precipitation of a small amount of crystalline sediment directly into the cavity of the organs of the urinary system. Over time, these crystals combine, mixing with the catarrhal secretion synthesized by the walls of the organ, as a result of which larger conglomerates are formed.

There are known cases when real cobblestones, the size of which exceeded eight centimeters in girth, were taken out of the bladder of unfortunate dogs! Considering that these stones do not have rounded edges, one can only imagine how painful this animal was during life...

Varieties

By the way, the term “bladder stones” is not entirely correct, since Uroliths can form in any part of the urinary system. And, by the way, in many cases their presence in the tubules is much more dangerous. Such neoplasms develop in the kidneys, ureters, urethra and, of course, in the bladder. It is believed that in approximately 85% of cases they end up in the latter. You need to understand that stones in the bladder can be formed from various compounds, and both the clinical picture and the treatment methods used depend on the characteristics of the latter.

So, veterinarians distinguish the following varieties: struvites formed by ammonium phosphorus salts, as well as oxolates and urates. The latter two may include: calcium oxalate, calcium phosphate, cystine, ammonium urate and other chemical compounds. To be fair, we note that “canonical” specimens are rarely found in the “wild”. More often than not, it is difficult to classify a stone as one type, since it is, in fact, a combination of all of the above salts. Because of this, it can be difficult to prescribe treatment, and difficulties arise in identifying “residents” in the bladder.

About the predisposition of animals

It is officially believed that predisposition, as such, does not exist. can be detected in dogs of any gender, age, breed. And it’s true: unlike cats, the Himalayan and Burmese breeds of which are noticeably more likely to suffer from stones in the urinary system, no such picture was found in any of the dog varieties.

But still Males, and especially old ones, get sick more often. In addition, in males, the disease in many cases is noticeably more severe. This is due to anatomical features: in females, small stones and sand often come out through the urethra on their own, but in males, due to the presence of an S-shaped bend of the penis, this “garbage” almost always gets stuck in the lumen of the organ. This leads to blockage of the urethra, dysuria (no urine is released), and severe intoxication. Death is possible either due to severe uremia, or due to internal uremia resulting from rupture of the walls of the organ. By the way, even the natural passage of stones from the bladder is fraught with such consequences: along the way, they damage the mucous membranes and tear blood vessels.

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Predisposing factors and pathogenesis of the disease

It all starts with a sharp change in the pH level of urine and the level of its saturation with soluble (relatively) salts of magnesium, calcium, phosphorus, etc. In the case when both of these factors act simultaneously, deposition of a crystalline precipitate begins. It is important to note here that this process is not a chain reaction. If at this moment the diet and feeding conditions are normalized, the dog stops taking any medications (tetracycline, for example, can provoke urolithiasis), then the development of the pathology stops. In many cases, a small amount of the resulting sand is simply excreted into the external environment in the urine.

But, unfortunately, this is not always the case. When a lot of sand accumulates in the cavity of an organ, it begins to greatly irritate and injure its mucous membrane. As a result, the latter secretes an increased volume of mucous secretion. Connecting with it, the sand “rolls” into conglomerates, from which the stones already known to us are formed.

Reasons influencing the appearance of uroliths include: genetic predisposition (not by breed, but by a specific breeding line), the concentration of mineral components in the urine, urine pH and the presence of bacterial infections of the genitourinary system. Separately, I would like to dwell on genetics. French veterinarians proved several years ago that some dogs, regardless of their breed and gender, always have elevated levels of mineral components in their urine. It is quite natural that the dogs themselves and all their offspring are the logical “lucky ones” who are at risk. It is for this reason that you should be careful when purchasing purebred puppies and very carefully check their entire pedigree.

The role of bacterial infections

Bacterial bladder infections (that is, cystitis) play an important role in the process of urolith formation, and there are several explanations for this. Firstly, such diseases lead to an increase in the pH level and its movement into the alkaline zone. This can already cause abundant precipitation of salts, called salts, when the animal consumes food with a low pH level. Normally, urine should have a neutral reaction, when the likelihood of developing a chemical reaction is reduced to zero.

But the presence of bacteria is dangerous not only for this. In particular, waste products of microorganisms themselves can precipitate, stimulating the development of uroliths. In addition, some bacteria synthesize an enzyme called urease. This compound, without going into the intricacies of organic chemistry, simply splits urine into its constituent components. Ammonia slowly turns into ammonium ions, while carbon dioxide combines with other components to form phosphates. Then, thanks to a chain of chemical reactions, magnesium, which is always present in the urine, combines with ammonium and phosphates. This is exactly how the same struvites are formed, which we already wrote about above.

Remember! The inflammatory reaction, which appears due to the action of pathogenic microflora, contributes to a sharp increase in the volume of mucous secretion. And, as we already know, it is an important “building” element of stones in the genitourinary system of an animal.

Clinical picture and diagnosis

How to understand that your pet has some problems with the urinary organs? It's simple. As a rule, in such cases, blood appears in the animal’s urine. This phenomenon is called. This pathology develops because the sharp and uneven edges of uroliths tear and injure the mucous membrane of the organ. But hematuria rarely appears on its own: most often it is accompanied by a severe pain reaction.

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The dog howls, whines, rolls on its back. In severe cases, when stones completely block the lumen of the urethra, urine accumulating in the cavity of the bladder literally “swells” the organ. Since the volume of an organ in a dog (especially a large one) can be decent, it is quite easy to notice a change in the animal’s figure. Looking at the male with urolithiasis, you can suspect his pregnancy: the dog begins to look like a pear.

When the owner tries to touch his belly, the pet may begin to behave inappropriately, since any touch can cause him severe pain. If you observe this in your dog, take him to the vet immediately. Further delay threatens bladder rupture and death from generalized internal bleeding.

A fairly characteristic sign of urolithiasis is the dog’s desire to “make a puddle” anywhere and at any time. Such animals constantly strain, trying to squeeze out at least a drop of urine, but they rarely succeed. During a walk, the dog constantly freezes for a long time, strains, wheezes and howls. Often, animals begin to constantly lick the genital area so that the fur in these places completely sticks together from saliva. In rare cases, the symptoms of urolithiasis are blurred or do not appear at all. This only happens when the stones do not have sharp edges, and their presence in the animal’s bladder does not interfere in any way.

As a rule, when making a diagnosis it is used radiographic examination abdominal cavity and the bladder itself. In most cases, the stones are clearly visible in the photographs. Problems begin if the tumor consists of substances through which X-rays pass freely, as a result of which nothing remains on the pictures. In this case, there are two options: either use contrast radiography, when a contrast solution is injected into the cavity of the bladder before “filming,” or conduct an ultrasound examination. After identifying the stones, you need to decide what to do next with the animal.

Therapeutic techniques

In most cases, removal of stones from the bladder is only possible through surgery. The operation is called "cystotomy", which literally means “opening the bladder.” In this case, the animal is given complete anesthesia, access to the organ is gained through an incision in the abdominal cavity, it is removed, and the urine is sucked out through a catheter. Afterwards, an incision is made, the stones are removed, and the bladder cavity is washed with sterile solutions to remove the smallest particles of uroliths.

Urine, by the way, with this technique is collected for additional research, including seeding the material on nutrient media. After the intervention, the bladder wall is sutured.

As a rule, the operation is easy, the dog is prescribed broad-spectrum antibiotics, and after a day in the clinic it is sent home. Stones removed from the organ are subjected to chemical analysis in order to prevent their occurrence later by adjusting the pet’s diet.

Sometimes a method known as "Urohydropropulsion" is used. The title can be translated as "pushing" stones. In this case, the dog is given local anesthesia and its bladder is filled with a sterile saline solution through a catheter. The animal is fixed in the pen, placed in an upright position, and the veterinarian, squeezing the bladder, pressing on the pet’s stomach, literally “squeezes out” the stones. But this technique is allowed only in cases where the uroliths are really small and are guaranteed to pass through the lumen of the urethra and/or catheter.

Sometimes none of these methods can be used in their “pure” form. For example, the dog is old (or simply weak), surgery is contraindicated for him, but the stones are too large and it is impossible to remove them through the urethra. In such cases, they can be used ultrasonic crushing. The stones are crushed into sand, and then washed using the method described in the tower. Unfortunately, some types of uroliths do not respond well to ultrasonic crushing, and in such situations it is necessary to find other methods.

Definitions of the concept " urolithiasis disease“You can give a lot. To put it simply, its essence is this: due to metabolic disorders in the body of dogs and cats, stones called uroliths or calculi form in the urine and urinary tract.

Urine is a complex solution, which is a necessary medium for removing metabolic products from the body. Metabolic products (urea and creatinine), minerals (calcium, magnesium, phosphates), electrolytes (sodium and potassium), water are excreted in the urine; urine pH varies depending on the homeostatic maintenance of acid-base balance. Any deviations from the norm can lead to the development of urolithiasis in animals. Mechanical blockage of the urinary tract by stones is the cause of urolithiasis. Stones can form both in the kidneys and in the urinary tract, but the clinical symptoms of urolithiasis are associated specifically with urinary tract disease.

Diagnosis. Urolithiasis is diagnosed when stones are detected in fresh urine, in the bladder through ultrasound or x-ray examination and stones are detected during surgery to remove them. The presence of stones in urine that has stood for more than an hour does not give grounds to draw a conclusion about urolithiasis, since uroliths can precipitate as a result of natural chemical reactions.

Uroliths vary greatly in composition - from homogeneous (cystines) to a complex mixture of minerals and even minerals and proteins. They also differ in appearance - from soft deposits of sandy material (mucoid plugs), which are mainly observed in cats and consist of a protein-like shell filled with mineral content, to hard, smooth or uneven stones, consisting mainly of minerals and small matrices. We will not describe in detail the properties of each of the stones; this is not the purpose of this article. Fellow veterinarians engaged in in-depth study of this problem can refer to the relevant manuals.

The formation of stones occurs for the following reasons:

1. If the concentration of urolith components in the urine is higher than the possibility of their dissolution and excretion without the formation of a crystal.
2. Some types of crystals are sensitive to urine pH. Thus, struvite is formed only in alkaline urine (PH> 7.0). Calcium oxalates are generally not sensitive to urine pH.
3. The formation of large crystals that can cause obstruction (blockage) of the urinary tract should occur very quickly, because When crystals form slowly, they are washed out of the bladder before they can cause harm.
4. The presence of a nucleus (base) to begin the formation of a large urolith. These may be remnants of cells, suture material, bacteria and, according to some sources, viruses.
5. Some bacterial infections can contribute to the development of urolithiasis. Thus, some bladder infections contribute to the development of struvite-type urolithiasis in dogs (especially in bitches and puppies in the first year of life).

Clinical symptoms of urolithiasis

The presence of uroliths in the urinary tract can cause clinical symptoms that may or may not be noticed by the pet owner. This is especially true for cats, since they hide from their owners and their owners do not always see their act of urination. The main clinical symptom is the inability to urinate naturally or urination is difficult.

In this case, the animal often sits down (male cats, females) or raises its paw (males), tries to urinate, whines, cries, urine is released in drops, often with blood.

Palpation of the abdomen establishes the presence of a full bladder. This procedure can always be performed in cats; in dogs, it is sometimes extremely difficult to palpate the abdominal wall due to the tense powerful muscles of the abdominal wall.

There are several degrees of urolithiasis:

1. Subclinical urolithiasis. There may be no symptoms associated with the presence of uroliths in the urinary tract. Struvite, calcium oxalate and other calcium-containing uroliths are radioopaque and are visible on x-rays. A urine test may show elevated crystals and an abnormal urine pH. These uroliths are usually struvite and sometimes calcium oxalate. Calcium oxalate stones often have a very rough surface and can cause mild to severe symptoms of urinary tract inflammation, while smooth struvite or cystine stones often cause no clinical symptoms at all. Nephroliths rarely cause clinical symptoms other than hematuria until they move into the ureter, causing obstruction (blockage) and hydronephrosis.

2. Mild symptoms of urolithiasis:

• Slight increase in urinary frequency
• Mild hematuria - blood staining
• Slight increase in urination time
• Slight discomfort during urination
• Increased licking of the genitals

3. Severe symptoms:

• Pollakiuria - cats almost never leave their toilet, dogs constantly leak drops of urine
• Urinary tenesmus (to be distinguished from constipation)
• Severe hematuria - obvious blood in the urine
• Severe discomfort when urinating - vocalization and obvious pain
• On palpation, the bladder is greatly distended
• Polydipsia/polyuria in case of secondary renal failure
• General depression and anorexia

4. Symptoms that threaten the animal's life:

• Anuria (lack of urination)
• Weakness/collapse
• Dehydration
• On palpation, the bladder may not be found if it has burst or is anuric (otherwise it feels like a dense mass)
• Uremic halitosis may be detected
• Vomit
• Convulsions

To prescribe adequate treatment, the veterinarian must be able to assess the degree of development of urolithiasis.

Diagnosis of urolithiasis

Urolithiasis is confirmed:

• Clinical symptoms
• Palpation of uroliths in the bladder in dogs (in cats they are difficult to palpate)
• Plain x-rays show radioopaque uroliths
• Contrast radiographs for radiolucent and small (less than 2 mm in diameter) uroliths
• Discharge of uroliths during urination (they can be collected in a net)

Radiography is necessary to determine radioopacity, location of deposition, number and size of uroliths. Usually stones are present in several places at once, so examination of all urinary tracts is necessary.

Rice. 1. Calcium oxalate crystals in urine

In cats, urolithiasis usually resolves with the formation of struvite (tripelphosphate), but recently there have been increasing cases of detection of calcium oxalates in the urine of cats and, even worse, mixed type urolithiasis, when both struvite and oxalates are present in the urine at a neutral urine pH level. Many veterinarians neglect laboratory diagnosis, relying on the prevalence of struvite in cats. I think this approach is wrong.

In dogs, KSD can occur with the formation of all known uroliths, therefore, laboratory visual determination of the type of stones for dogs is very important for prescribing treatment. A 10-mL sample of fresh urine sediment should be microscopically examined immediately after collection at body temperature because time, cooling, or evaporation of the urine may accelerate crystal precipitation and produce false positive or paradoxical results. Most common crystals have a typical appearance in urine, and if their number is large, one can judge the composition of the urolith, or at least its outer layer.

Rice. 2. Struvite

Rice. 3. Struvite and red blood cells in urine

Treatment of urolithiasis

The choice of the correct treatment depends on the location(s) of the uroliths:

Kidneys- nephroliths are very difficult to remove surgically, unless they are concentrated in one kidney. Then nephrectomy (kidney removal) is possible. With nephrolitas, the development of postrenal renal failure is possible. Dissolution of struvite uroliths is possible by prescribing a special diet.

Ureters- uroliths located in the ureters can be successfully removed surgically, but one should remember the possibility of developing postrenal renal failure.

Bladder- treatment depends on the type of uroliths. Struvite, urate, and sometimes cystine can be dissolved, and calcium oxalate and other calcium- and silica-containing uroliths can be removed surgically by conventional cystotomy (opening the bladder and removing stones).

Urethra- depending on how the uroliths lie, several types of treatment are used:

1) Manipulation - manual massage(often used for cats with sand plugs) or catheterization a small polyurethane catheter (for example, a special Jackson catheter for cats or a medical subclavian catheter with a diameter of 0.6 - 0.8 mm).

Despite the fact that catheterization is often used to displace or break up uroliths in cats and some breeds of dogs, this method of treatment is the most dangerous for the following reasons:

• it injures the tissue, which leads to fibrosis and scarring with subsequent narrowing of the urethra;
• causes infection in the urinary tract.

2) Retrograde urethral lavage followed by dissolution (struvite, urate and cystine) or cystotomy (calcium oxalates, other uroliths containing calcium and silicon dioxide) is the only method of treating urethral urolithiasis.

Method of retrograde washing out of urethral stones

The animal is given general anesthesia or strong sedatives. Then the following steps are performed:

• Empty the bladder by cystocentesis (puncture of the bladder through the abdominal wall)
• Through the rectum, fingers compress the urethra opposite the pubis, below the urolith (an assistant is needed for this)
• A sterile catheter is inserted into the distal urethra
• Secure the penile part of the urethra around the catheter
• A sterile saline solution is injected into the catheter through a syringe.
• When the intraluminal pressure reaches the desired point, the assistant removes his fingers and releases the urethra
• Under the pressure of the saline solution, the urolith returns back to the bladder
• You can repeat the procedure several times

After retrograde lavage, recurrence of obstruction is very rare. This method, as a rule, is not used in cats; in males, this low-traumatic method is often recommended for use.

3) Urethrostomy used for males when manipulation or retrograde lavage has not been successful. A urethrostomy creates a permanent opening in the urethra. This method is used for recurrent obstructions of the penile urethra in cats and sometimes in males. Although this is the only method of treating animals with permanent urethral obstruction, it must be used with caution, because according to some data, in 17% of cases, urethrostomy in cats leads to postoperative urinary tract infection. In 10% of cats, urethrostomy and dietary changes also result in postoperative infection, while none of the cats treated with diet develop a urinary tract infection.

Dissolution

Struvite, urate and cystine stones can be dissolved. This is the only method for removing stones in animals with non-life-threatening urolithiasis. Dissolution is used for kidney or bladder stones. If a urinary tract infection is present, antibiotics are prescribed as part of treatment based on the results of urine culture and sensitivity testing. Treatment details are discussed below.

Struvite (magnesium ammonium phosphate, tripel phosphates). To dissolve struvite stones, it is enough to strictly adhere to special veterinary diets. They are represented quite widely on the Russian market; any veterinary clinic in Moscow and large Russian cities can offer a veterinary diet for your pet. We successfully use food from Purina (UR) and Hills (s/d, c/d).

These foods contribute to the acidification of urine, causing the dissolution of struvite. In addition, the increased sodium content in these diets stimulates diuresis (urination), which helps flush the bladder and speed up the elimination of accumulated salts. For urolithiasis not complicated by bacterial infections, treatment with special diets brings positive results already 4-5 days after the start of treatment. It should be noted that contacting a veterinarian as early as possible and early diagnosis of urolithiasis promotes a speedy recovery of the animal and minimizes possible relapses of the disease. The owner's compliance with the animal's feeding regime is of great importance. THE ANIMAL CANNOT BE GIVEN ANYTHING ELSE EXCEPT A SPECIAL DIET!!!

Quality control of treatment is carried out by laboratory tests of urine and x-ray diagnosis of the presence of stones in the bladder. If there are no stones in the urine and in the photographs, the treatment is considered effective and the owner’s task in the future is a MANDATORY urine test at least once every six months. In our opinion, the optimal period for control testing is 3 months.

Laboratory assessment of urine pH, as well as the presence and analysis of urine sediment, determination of the type and quantity of urinary crystals.

Treatment of insoluble uroliths

-Calcium oxalates
Calcium oxalate uroliths are more common in certain breeds of dogs (Yorkshire terriers and miniature schnauzers), and in recent years they have become noticeably more common, especially in cats.
Unfortunately, this type of crystals is completely insoluble, and treatment of this type of urolithiasis is carried out exclusively surgically, removing stones from the bladder. Sometimes 3-4 operations per year are required if the intensity of oxalate formation is very high.
To prevent relapses, it is necessary to reduce the concentration of calcium and oxalates in the urine. Prevention is possible with special diets (Hills x/d, Eucanuba Oxalat Urinary Formula, etc.). I repeat. PREVENTION. But not the dissolution of oxalate stones!

-Calcium phosphates
Calcium phosphate crystalluria manifests itself in various forms: both amorphous (calcium phosphates) and calcium hydrogen phosphates (brushite). These minerals are often present in mixed uroliths along with struvite, urate, or calcium oxalate. Most calcium phosphate crystals (with the exception of brushite) are sensitive to urine pH and form in alkaline urine.
A medical protocol for dissolving these uroliths has not yet been developed, so surgical removal and prevention of hypercalciuria (as in the case of calcium oxalate urolithiasis), but not urine alkalinization, are recommended.

-Silicon dioxide (silicates)
Silicate uroliths are rare in dogs. They are called "Jack stones." The etiopathogenesis of these uroliths is not completely clear, however, it is believed that the risk of the formation of these stones increases if the dog eats soil or types of vegetables contaminated with soil (rutabaga, beets). Personally, I have never encountered this type of urolithiasis.
For clinical symptoms, the only treatment is surgical removal of stones, and as a preventive measure, it is recommended to ensure that the dog does not eat soil or vegetation contaminated with it.