General analysis urine includes assessment physicochemical characteristics of urine and microscopy of sediment. This study allows you to evaluate renal function and other internal organs, as well as identify the inflammatory process in the urinary tract. Together with the general clinical analysis blood, the results of this study can tell quite a lot about the processes occurring in the body and, most importantly, indicate the direction of further diagnostic search.
Indications for the purpose of analysis:
Secondary ketonuria:
- thyrotoxicosis;
- Itsenko-Cushing's disease; overproduction of corticosteroids (tumor of the anterior pituitary gland or adrenal gland);
Hemoglobin.
Norm: dogs, cats - absent.
Hemoglobinuria is characterized by red or dark brown (black) urine and dysuria. Hemoglobinuria must be distinguished from hematuria, alkaptonuria, melaninuria, and porphyria. With hemoglobinuria, there are no red blood cells in the urine sediment, anemia with reticulocytosis and an increase in the level of indirect bilirubin in the blood serum are detected.
When does hemoglobin or myoglobin appear in the urine (hemoglobinuria)?
Hemolytic anemia.
- Severe poisoning (sulfonamides, phenol, aniline dyes,
- After an epileptic seizure.
- Transfusion of incompatible blood group.
- Piroplasmosis.
- Sepsis.
- Severe injuries.
Microscopy of urinary sediment.
In urinary sediment, organized sediment is distinguished (cellular elements, cylinders, mucus, bacteria, yeast fungi) and unorganized (crystalline elements).
Red blood cells.
Norm: dogs, cats - 1 – 3 red blood cells in the field of view.
Everything above is hematuria.
Highlight:
- gross hematuria (when the color of urine is changed);
- microhematuria (when the color of urine is not changed, and red blood cells are detected only under a microscope).
In urinary sediment, red blood cells can be unchanged or changed. The appearance of altered red blood cells in the urine is of great diagnostic importance, because they are most often of renal origin. Unmodified red blood cells are more likely to cause damage to the urinary tract ( urolithiasis disease, cystitis, urethritis).
When does the red blood cell count increase (hematuria)?
Urolithiasis disease.
- Tumors of the genitourinary system.
- Glomerulonephritis.
- Pyelonephritis.
- Infectious diseases urinary tract (cystitis, tuberculosis).
- Kidney injury.
- Poisoning with benzene derivatives, aniline, snake venom, anticoagulants, poisonous mushrooms.
Leukocytes.
Norm: dogs, cats - 0–6 leukocytes in the field of view.
When does the white blood cell count increase (leukocyturia)?
Spicy and chronic glomerulonephritis, pyelonephritis.
- Cystitis, urethritis, prostatitis.
- Stones in the ureter.
- Tubulointerstitial nephritis.
Epithelial cells.
Norm: dogs and cats – single or absent.
Epithelial cells have different origins:
- squamous epithelial cells (washed off with night urine from the external genitalia);
- transitional epithelial cells (lining the mucous membrane Bladder, ureters, pelvis, large ducts of the prostate gland);
- cells of the renal (tubular) epithelium (lining the renal tubules).
When does the number of epithelial cells increase?
Cell enhancement squamous epithelium significant diagnostic value does not have. It can be assumed that the patient was not properly prepared for the test collection.
Cell enhancement transitional epithelium:
- intoxication;
- intolerance to anesthesia, medicines, after operations;
- jaundice of various etiologies;
- urolithiasis (at the moment of stone passage);
- chronic cystitis;
Appearance of cells renal epithelium:
- pyelonephritis;
- intoxication (taking salicylates, cortisone, phenacetin, bismuth preparations, salt poisoning heavy metals, ethylene glycol);
- tubular necrosis;
Cylinders.
Norm: dogs and cats are absent.
The appearance of casts (cylindruria) is a symptom of kidney damage.
When and what casts appear in a general urine test (cylindruria)?
Hyaline casts are found in all organic diseases kidneys, their number depends on the severity of the condition and the level of proteinuria.
Grain cylinders:
- glomerulonephritis;
- pyelonephritis;
- kidney cancer;
- diabetic nephropathy;
- infectious hepatitis;
- osteomyelitis.
Waxy cylinders indicate severe kidney damage.
Leukocyte casts:
- acute pyelonephritis;
- exacerbation of chronic pyelonephritis;
- kidney abscess.
Red blood cell casts:
- kidney infarction;
- embolism;
- acute diffuse glomerulonephritis.
Pigment cylinders:
- prerenal hematuria;
- hemoglobinuria;
- myoglobinuria.
Epithelial casts:
- acute renal failure;
- tubular necrosis;
- acute and chronic glomerulonephritis.
Fat cylinders:
- chronic glomerulonephritis and pyelonephritis complicated by nephrotic syndrome;
- lipoid and lipoid-amyloid nephrosis;
- diabetic nephropathy.
Bacteria.
Fine urine in the bladder is sterile. The detection of bacteria in a urine test of more than 50,000 in 1 ml indicates an infectious lesion of the urinary system (pyelonephritis, urethritis, cystitis, etc.). The type of bacteria can only be determined through bacteriological examination.
Yeast fungi.
The detection of yeast of the genus Candida indicates candidiasis, which most often occurs as a result of irrational antibiotic therapy, the use of immunosuppressants, and cytostatics.
Determining the type of fungus is possible only through bacteriological examination.
Slime.
Mucus is secreted by the epithelium of the mucous membranes. Normally absent or present in urine in small quantities. During inflammatory processes in the lower parts of the urinary tract, the mucus content in the urine increases.
Crystals (disorganized sediment).
Urine is a solution of various salts, which can precipitate (form crystals) when the urine stands. The presence of certain salt crystals in the urinary sediment indicates a change in the reaction towards the acidic or alkaline side. Excessive salt content in urine contributes to the formation of stones and the development of urolithiasis.
When and what kind of crystals appear in a general urine test?
- Uric acid and its salts (urates): can normally be found in Dalmatians and English bulldogs; in dogs of other breeds and cats they are associated with liver failure and porosystemic anastomoses.
- Tripelphosphates, amorphous phosphates: often found in slightly acidic or alkaline urine in healthy dogs and cats; may be associated with cystitis.
Calcium oxalate:
Severe infectious diseases;
- pyelonephritis;
- diabetes;
- ethylene glycol poisoning;
Cystine:
Cirrhosis of the liver;
- viral hepatitis;
- state of hepatic coma
- Bilirubin: may occur in healthy dogs with concentrated urine or due to bilirubinuria.
A urine test is important for a person who can tell the doctor where and how it hurts, and even more so for a dog, which, unfortunately, cannot tell us about its pain.
However, if you take a urine test at medical laboratory This is normal, but a trip to a veterinary laboratory with dog excrement is still quite rare.
Factors influencing the composition of urine in dogs
Urine that is excreted (diuresis) is a waste product of the body. Its composition is influenced by:
- pathological factors (infection, invasion,);
- physiological (pregnancy, estrus, weight, type of feeding);
- climatic (temperature, humidity).
Stress can affect the composition of your urine.
Conducting experiments and studies with clinically healthy animals, biologists calculated the parameters that are present in urine and characterize the physiological balance of the functioning of systems and organs.
Composition and parameters of the norm
The basis of urine is water, its normal content is 97–98%. The following components are included in its composition:
- organic;
- inorganic.
According to physical parameters, a dog’s urine should be yellow or light yellow (depending on the food consumed), transparent, and without a strong odor.
Normally, the color of urine should be yellow.
Table of organic components (norm for dogs)
Density
The specific gravity of urine is an indicator that characterizes how much the kidneys can concentrate urine by reabsorbing water.
The density of urine allows you to assess kidney activity.
pH Indicator of acid balance
Urine, normally, can be either acidic or alkaline. By this indicator we can judge the dog’s feeding diet. The more protein food is contained in the four-legged bowl, the more acidic the urine.
Protein feeds increase the acidity of urine.
The acidified indicator will be during fasting, prolonged physical activity, however, this will not indicate pathology.
Protein
A substance consisting of amino acids should not normally leave the body.
The appearance of protein in the urine may sometimes not be associated with pathology. This phenomenon occurs with excessive physical exertion, as well as overfeeding the dog with food of animal origin, or when the diet is not balanced in protein.
The appearance of protein occurs during heavy physical activity.
Glucose
An indicator that makes it possible to understand whether things are happening correctly carbohydrate metabolism at the dog.
Normally, all carbohydrates should be absorbed, but if there is an excess of them in the diet, then some of them will be excreted in the urine.
Excess glucose will be excreted in the urine.
Often this message is deceptive. Since diagnostic strips react to the level ascorbic acid, and it can be synthesized in dogs in fairly high concentrations.
Bilirubin
A component of bile. The appearance of traces of bilirubin may indicate.
Detected bilirubin indicates liver pathologies.
Ketone bodies
If ketone bodies are found along with increased sugar content, this indicates.
Ketone bodies alone can be normal during prolonged fasting, or when there is an excess of fat in the dog’s diet.
Ketone bodies are released during fasting.
Microscopic studies
After settling, the urine releases sediment. Having examined it under a microscope, its components are divided into organic and mineral origin.
Under a microscope, the urine sediment is divided into parts.
Organic sediments
- Red blood cells can be found as organic. Such a “find” may indicate a pathology of the urinary tract.
- Leukocytes can be found normally, but not more than 1–2. If the quantity is higher, this indicates kidney pathology.
- Epithelial cells are always present in urine sediment, since the epithelial cover is constantly changing, but this indicator is more pronounced in females.
- If detected increased number of cylinders , then this may indicate pathology of the kidneys and urinary system.
The presence of red blood cells indicates urinary tract disease.
Inorganic sediments
If the urine pH is acidic, then uric acid, calcium phosphate, and calcium sulfate may predominate. If the reaction is closer to alkaline, then amorphous phosphates, magnesium phosphate, calcium carbonate, tripel phosphate may be present.
When uric acid(normally it should not be) we can talk about strong physical exertion on the dog, or overfeeding with meat food. At pathological processes, such as uric acid diathesis, febrile conditions, tumor processes, uric acid will be present in significant quantities.
When you overfeed meat, uric acid appears.
If the dog's urine is closer to brick in color, then amorphous urates will precipitate. At physiological norm such processes are impossible. The presence may indicate fever.
Oxalates
Oxalates (producers of oxalic acid) can be in units. If there are many of them in the field of view, then diabetes mellitus, pyelonephritis, and calcium pathology are possible.
The detection of calcium carbonate will not be a pathology if the dog is fed exclusively with food of plant origin, otherwise it will indicate.
If your dog is a Dalmatian Great Dane or a puppy, ammonium urate will be present in the urine normally. In other cases, it may indicate bladder inflammation.
In Dalmatian Great Danes, the presence of ammonium urate is normal.
Crystals and neoplasms
- If found tyrosine or leucine crystals , then the pathology can be caused by leukemia or phosphorus poisoning.
- On kidney tumors , or degenerative processes in them will be indicated by the presence of cholesterol crystals in the sediment.
Tyrosine crystals can be caused by leukemia.
Fatty acid
Sometimes fatty acids can be detected in the urine. Their presence indicates dystrophic changes in the renal tissue, namely the disintegration of the epithelium of the renal tubules.
The presence of fatty acids indicates changes in the kidney tissue.
Bacteriological urine analysis
The detection of bacteria in the field of view of a microscope cannot indicate pathology or normality, but the fact itself is a prerequisite for conducting bacterial analysis.
When inoculating urine on nutrient media and identifying the level ranging from 1000 to 10000 microbial bodies in one milliliter of urine, for females this will be the norm, but for males it may indicate the beginning inflammatory processes in the genitourinary organs.
Such a urine test is carried out, as a rule, not so much to identify microflora, but to isolate a pure culture and subtitrate the sensitivity of antibiotics, which are then used to treat the animal.
Bacteriological analysis of urine is carried out to determine sensitivity to antibiotics.
Urine analysis for fungi
When sown on nutrient media, microscopic fungi germinate at certain temperatures. Normally, they are absent, but long-term treatment antibiotics, and diabetes mellitus can activate the growth of pathogenic microflora.
Urine analysis can be carried out qualitatively, using test systems (strips that are not always adapted for veterinary diagnostics) and quantitatively, in the laboratory.
If the initial analysis of the test system showed deviations in one direction or another, this is not yet a reason to panic. Quantitative measurements of urine parameters are necessary. Research should be carried out in a veterinary laboratory, and only one that has the right to conduct certain research.
Urinalysis must be performed in a laboratory setting.
conclusions
It is necessary to clearly understand that not having research results is better than having incorrect ones. Urine examination is intended not only to identify pathology, but also to differentiate the disease. Any inaccuracy is fraught with purpose improper treatment, which in turn can lead to irreversible consequences.
Urine examination will help to identify pathologies in time.
Video about dog urine analysis
In dogs, urea is 4 - 6 mmol/liter (24 - 36 mg/dl).
In cats, urea is 6 - 12 mmol/liter (36 - 72 mg/dl).
Standards vary slightly from laboratory to laboratory.
For recalculation:
mmol/liter divided by 0.166 gives mg/dl. Mg/dl multiplied by 0.166 gives mmol/liter.
Increased in renal failure
At renal failure urea rises.
Typically, an increase of up to 20 mmol/liter may not be externally noticeable.
If urea is more than 30 mmol/liter, then appetite worsens or disappears.
When urea is above 60 mmol/liter it usually happens frequent vomiting, then vomiting blood.
Rare cases
Some animals with chronic renal failure can feel quite well and maintain their appetite even with urea of 90 mmol/liter.
In our practice, there was a live animal with urea 160 mmol/liter.
Origin of urea
Approximately half of the urea is formed in the liver during biochemical protein reactions. The second half is also formed in the liver, but during the neutralization of ammonia coming from the intestines.
During fasting, a state of hypercatabolism develops and the formation of urea as a result metabolic processes increases.
When defecation is delayed, especially with micro or macro bleeding in the intestines, the formation of ammonia sharply increases as a result of putrefactive processes, and as a result, urea in the blood increases.
Other cases of increased urea in the blood
High protein diet.
Putrefactive processes in the intestines as a result of dysbacteriosis, lack of bile, and eating not fresh foods.
Bleeding in the stomach or intestines.
With normally functioning kidneys, in all of the above cases, urea rarely exceeds 30 mmol/liter, at the same time creatinine remains within normal limits, and in renal failure, creatinine is also increased.
Cases of decreased blood urea
Prolonged protein fasting.
Cirrhotic changes in the liver. In this case, ammonia from the intestines is not completely converted into urea.
Polyuria, polydipsia. Along with more fluid, more urea is removed from the body. With PN, even with polyuria, urea in the blood remains elevated.
Toxicity of urea to the body
Urea is neutralized ammonia, so urea itself is not toxic.
But very high urea increases the osmolarity of the blood plasma, and this can have harmful effects on the body.
When a lot of urea is released from the blood into the stomach, the urea turns into ammonia, which irritates the walls of the stomach and intestines and increases ulcerative damage to the mucous membrane.
Urea is a marker of toxicosis
In general, urea is used in analyzes as a marker of the amount of toxic metabolic products of approximately the same molecular weight.
The formation and release of urea are not constant values, depending on many factors, therefore, when the same numbers in analyzes general state animals may be different.
How to correctly take blood tests for urea during PN
Urea tests can be done in whole blood, plasma or serum, depending on the capabilities of the instruments.
You can take blood at any time, in any condition, because with renal failure, fluctuations in indicators decrease.
Treatment of kidney failure in animals
Urolithiasis (urolithiasis) in dogs is a phenomenon of the formation and presence of uroliths in the urinary tract (kidneys, ureters, bladder and urethra). Uroliths ( uro– urine, lith– stone) - organized concretions consisting of minerals (primarily) and a small amount of organic matrix.
There are three main theories of the formation of urinary stones: 1. Precipitation-crystallization theory; 2. Matrix-nucleation theory; 3. Crystallization–inhibition theory. According to the first theory, oversaturation of urine with one or another type of crystals is put forward as the main reason for the formation of stones and, consequently, urolithiasis. In the theory of matrix nucleation, the presence of various substances in the urine that initiate the onset of urolith growth is considered as the reason for the formation of uroliths. In the theory of crystallization-inhibition, it is assumed that there are factors in the urine that inhibit or provoke the formation of stones. Oversaturation of urine with salts in dogs is considered to be the main cause of urolithiasis; other factors play a less significant role, but can also contribute to the pathogenesis of stone formation.
Most canine uroliths are identified in the bladder or urethra. The predominant type of urinary stones are struvite and oxalate, followed by urate, silicate, cystine and mixed types in frequency of occurrence. Over the past twenty years, an increased percentage of oxalates has been noted, presumably this phenomenon has developed due to the widespread use of industrial feed. An important reason The formation of struvite in dogs is a urinary tract infection. Below are the main factors that can increase the risk of dogs developing one or another type of urolithiasis.
Risk factors for the development of urolithiasis in dogs with the formation of oxalates
Oxalate urinary stones are the most common type of uroliths in dogs; the incidence of urolithiasis with this type of stones has increased significantly over the past twenty years, along with a decrease in the incidence of struvite-predominant stones. The composition of oxalate urinary stones includes calcium oxalate monohydrate or dihydrate, outer surface usually have sharp, jagged edges. From one to many uroliths can form, the formation of oxalates is characteristic of acidic dog urine.
Possible reasons for the increased incidence of oxalate uroliths in dogs include demographic and dietary changes in dogs that have occurred during this period. These factors may include feeding an acidifying diet (widespread use of industrial feeds), an increase in the incidence of obesity and an increase in the percentage of breeds prone to the formation of a certain type of stone.
A breed predisposition to urolithiasis with the formation of oxalates has been noted in representatives of such breeds as the Yorkshire Terrier, Shih Tzu, Miniature Poodle, Bichon Frize, Miniature Schnauzer, pomeranian spitz, Cairn Terrier, Maltese and Kesshund. Gender predisposition has also been noted in castrated males of small breeds. Urolithiasis due to the formation of oxalate stones is more often observed in middle-aged and elderly animals (average age 8-9 years).
In general, the formation of uroliths is more related to the acid-base balance of the animal's body than to the specific pH and composition of urine. Dogs with oxalate urolithiasis often exhibit transient hypercalcemia and hypercalciuria after feeding. Thus, uroliths can form against the background of hypercalcemia and the use of calciuretics (eg furosemide, prednisolone). Unlike struvite, urinary tract infection with oxalate uroliths develops as a complication of urolithiasis, and not as the root cause. Also, with the oxalate form of urolithiasis in dogs, there is a high percentage of relapse after stone removal (about 25%-48%).
Risk factors for the development of urolithiasis in dogs with struvite formation
According to some data, the percentage of struive urinary stones to the total number is 40%-50%, but beyond last years There was a significant decrease in the incidence of struvite urolithiasis in favor of oxalate urolithiasis (see above). Struvite consists of ammonium, magnesium and phosphate ions, the shape is rounded (spherical, ellipsoidal and tetrahedral), the surface is often smooth. With struvite urolithiasis, both single and multiple uroliths with different diameters can form. Struvite in the canine urinary tract is most often located in the bladder, but can also occur in the kidneys and ureter.
The vast majority of canine struvite urinary stones are induced by a urinary tract infection (usually Staphylococcus intermedius, but may also play a role Proteus mirabilis.). Bacteria have the ability to hydrolyze urea to ammonia and carbon dioxide, this is accompanied by an increase in urine pH and contributes to the formation of struvite urinary stones. In rare cases, dog urine can be oversaturated with the minerals that make up struvite, and then urolithiasis develops without the involvement of infection. Based possible reasons struvite urolithiasis in dogs, even with a negative urine culture, the search for infection continues and it is preferable to culture the bladder wall and/or stone.
With urolithiasis in dogs with the formation of struvite uroliths, a breed predisposition has been noted in such representatives as the miniature schnauzer, bichon frise, cocker spaniel, shitzu, miniature poodle and Lhasa apso. Age predisposition was noted in middle-aged animals, and gender predisposition in females (presumably due to an increased incidence of urinary tract infections). The American Cocker Spaniel may have a predisposition to form sterile struvites.
Risk factors for the development of urolithiasis in dogs with the formation of urates
Urate urinary stones account for about a quarter (25%) of all stones delivered to specialized veterinary laboratories. Urate stones consist of a monobasic ammonium salt of uric acid, are small in size, their shape is spherical, the surface is smooth, the multiplicity of urolithiasis is characteristic, the color ranges from light yellow to brown (maybe green). Urate stones usually crumble easily, and concentric layering is visible on the fracture. With urate urolithiasis, a certain predisposition to urolithiasis has been noted in male dogs, presumably due to the smaller lumen of the urethra. Also, with urolithiasis in dogs with the formation of urates, a high percentage of relapses after stone removal is characteristic, it can be 30%-50%.
Unlike representatives of other breeds, the Dalmatian has a violation of purine metabolism, which leads to the release of increased amounts of uric acid and a predisposition to the formation of urates. It should be remembered that not all Dalmatians develop urates, despite the congenital increased level uric acid in animal urine, clinically significant illness determined in animals in 26%-34% of cases. Some other breeds (English Bulldog and Black Russian Terrier) may also have a hereditary predisposition to impaired purine metabolism (similar to Dalmatians) and a tendency to the urate form of urolithiasis.
Another reason for the formation of urates is microvascular dysplasia of the liver, which disrupts the conversion of ammonia to urea and uric acid to allantoin. With the above disorders of the liver, a mixed form of urolithiasis is more often observed; in addition to urates, struvite is also formed. A breed predisposition to the formation of this type of urolithiasis has been noted in breeds predisposed to the formation (eg Yorkshire Terrier, Miniature Schnauzer, Pekingese).
Risk factors for the development of urolithiasis in dogs with the formation of silicate stones
Silicate uroliths are also rare and cause urolithiasis in dogs (about 6.6% of cases). total number urinary stones), they consist mostly of silicon dioxide (quartz) and may contain small amounts of other minerals. The color of silicate urinary stones in dogs is gray-white or brownish, and multiple uroliths are more often formed. A predisposition to the formation of silicate stones has been noted in dogs fed a diet high in gluten grains (gluten) or soybean skins. The relapse rate after stone removal is quite low. As with oxalate urolithiasis, urinary tract infection is considered a complicating rather than a causative factor in the disease.
Risk factors for the development of urolithiasis in dogs with the formation of cystine
Cystine uroliths are rare in dogs (about 1.3% of the total number of urinary stones), they consist entirely of cystine, they are small in size, spherical in shape. The color of cystine stones is light yellow, brown or green. The presence of cystine in the urine (cystinuria) is considered a hereditary pathology with impaired transport of cystine in the kidneys (± amino acids), the presence of cystine crystals in the urine is regarded as a pathology, but not all dogs with cystinuria form the corresponding urinary stones.
A number of dog breeds have been shown to have a breed predisposition to the disease, such as the English Mastiff, Newfoundland, English Bulldog, Dachshund, Tibetan Spaniel and Basset Hound. Cystine urolithiasis in dogs has an exclusive gender predisposition in males, with the exception of the Newfoundland. Average age The development of the disease is 4-6 years. When removing stones, a very high percentage of relapses of their formation was noted, it is about 47%–75%. As with oxalate urolithiasis, urinary tract infection is considered a complicating rather than a causative factor in the disease.
Risk factors for the development of urolithiasis in dogs with the formation of hydroxyapatite (calcium phosphate)
This type of urolith is extremely rarely observed in dogs, and apatite (calcium phosphate or calcium hydroxyl phosphate) often acts as a component of other urinary stones (usually struvite). Alkaline urine and hyperparathyroidism predispose to precipitation of hypoxyapatitis in the urine. The following breeds have been shown to be predisposed to the formation of this type of urinary stones: Miniature Schnauzer, Bichon Frize, Shih Tzu and Yorkshire Terrier.
Clinical signs
Struvite urinary stones are more often found in females, due to their increased susceptibility to urinary tract infections, however; clinically significant urethral obstruction is more common in males due to their narrower and longer length urethra. Urolithiasis in dogs can occur at any age, but is more common in middle-aged and elderly animals. Urinary stones in dogs under 1 year of age are most often struvite and develop due to a urinary tract infection. With the development of the oxalate form of urolithiasis in dogs, the development of stones is more often observed in males, especially in breeds such as miniature schnauzer, Shitzu, Pomeranian, Yorkshire terrier and Maltese. Also, oxalate urolithiasis in dogs is observed at an older age compared to the struvite type of urolithiasis. Urates are more often formed in Dalmatians and English bulldogs, as well as dogs predisposed to the development. Cystine uroliths also have a certain breed predisposition, the table below contains general information on the incidence of urolithiasis in dogs.
Table. Breed, gender and age predisposition for the formation of urinary stones in dogs.
|
Type of stones |
Morbidity |
|
Struvite |
Breed Predisposition: Miniature Schnatsuer, Bichon Frize, Cocker Spaniel, Shih Tzu, Miniature Poodle, Lhasa Apso. Sexual predisposition in females Age predisposition – middle age The main predisposing factor to the development of struvitis is infection of the urinary tract with urease-producing bacteria (ex. Proteus, Staphylococcus). |
|
Oxalates |
Breed Predisposition – Miniature Schnauzer, Shih Tzu, Pomeranian, Yorkshire Terrier, Maltese, Lhasa Apso, Bichon Frize, Cairn Terrier, Miniature Poodle Sexual predisposition – more often in castrated males than in non-castrated males. Age predisposition: middle and old age. One of the predisposing factors is obesity |
|
Breed predisposition – Dalmatian and English bulldog The main factor predisposing to the development of urates is a portosystemic shunt, and accordingly it is more often observed in predisposed breeds (eg Yorkshire Terrier, Miniature Schnauzer, Pekingese) |
|
|
Silicates |
Breed predisposition - German Shepherd, old English sheepdog Gender and age predisposition – middle-aged males |
|
Breed Predisposition – Dachshund, Basset Hound, English Bulldog, Newfoundland, Chihuahua, Miniature Pinscher, Welsh Corgi, Mastiffs, Australian Cowdog Gender and age predisposition – middle-aged males |
|
|
Calcium phosphate |
Breed predisposition – Yorkshire Terrier |
The history of urolithiasis in dogs depends on the specific location of the stone, the duration of its presence, various complications and diseases predisposing to the development of the stone (etc.).
When urinary stones are found in the kidneys, animals are characterized by a long asymptomatic course of urolithiasis; there may be blood in the urine (hematuria) and signs of pain in the kidney area. With the development of pyelonephritis, the animal may experience fever, polydipsia/polyuria and general depression. Ureteral stones in dogs are diagnosed quite rarely; dogs may experience various signs pain in the lumbar region, most animals often develop a unilateral lesion without systemic involvement, and the stone may be discovered as an incidental finding in the context of renal hydronephrosis.
Canine bladder stones represent the vast majority of cases of canine urolithiasis; owner complaints upon presentation may include signs of difficulty and frequent urination, hematuria sometimes occurs. The displacement of stones into the urethra of male dogs can lead to partial or complete obstruction of the outflow of urine, in which case the primary complaints may be signs of strangury, abdominal pain and signs of postrenal renal failure (eg anorexia, vomiting, depression). In rare cases of complete obstruction of urine outflow, complete rupture of the bladder with signs of uroabdomen may develop. It should be remembered that urinary tract stones in dogs can be asymptomatic and are detected as an incidental finding during plain radiographic examination.
Physical examination data for urolithiasis suffer from poor specificity of symptoms. With unilateral hydronephrosis in dogs, an enlarged kidney (renomegaly) may be detected during palpation examination. With obstruction of the ureters or urethra, pain may be detected abdominal cavity, when the urinary tract ruptures, signs of the uroabdomen and general depression develop. During a physical examination, bladder stones can be detected only if they are of a significant number or volume; upon palpation, the sounds of crepitus can be detected or a urolith of significant size can be palpated. With obstruction of the urethra, palpation of the abdomen can reveal an enlarged bladder, rectal palpation can reveal a stone localized in the pelvic urethra, and if the stone is localized in the urethra of the penis, in some cases it can be palpated. When attempting to catheterize the bladder of an animal with urethral obstruction, a veterinary clinician may identify mechanical resistance to the catheter.
The most radiopaque urinary stones are uroliths containing calcium (calcium oxalates and phosphates); struvites are also well identified by plain radiographic examination. The size and number of radiopaque stones is best determined by X-ray examination. Double contrast cystography and/or retrograde urethrography can be used to identify radiolucent stones. Ultrasound diagnostic methods can detect radiolucent stones in the ureter of the bladder and urethra, in addition, ultrasound can help in assessing the kidneys and ureter of the animal. When examining a dog with urolithiasis, radiographic and ultrasound methods are usually used together, but, according to many authors, double contrast cystography is the most sensitive method for identifying bladder stones.
Laboratory tests for a dog with urolithiasis include a complete blood count, a biochemical profile of the animal, a complete urinalysis, and a urine culture. In case of canine urolithiasis, even in the absence of obvious urinary tract infection, hematuria and proteinuria, there is still a high probability of urinary tract infection, and it is preferable to use additional research methods (eg. cytological examination urine, urine culture). A biochemical blood test can determine signs of liver failure (ex. high level blood urea nitrogen, hypoalbuminemia) in dogs with.
Diagnosis and differential diagnosis
Urinary stones should be suspected in all dogs with signs of urinary tract infection (eg hematuria, stranguria, pollakiuria, urinary obstruction). List differential diagnoses includes any form of bladder inflammation, urinary tract neoplasms and granulomatous inflammation. Detection of uroliths as such is carried out through visual examination methods (radiography, ultrasound), in rare cases, identification of uroliths is possible only intraoperatively. Determining the specific type of urolith requires its examination in a specialized veterinary laboratory.
It should be remembered that the identification of most crystals in urine does not always indicate pathology (with the exception of cystine crystals); in many dogs with urolithiasis, the type of crystals found in the urine may differ in composition from urinary stones; crystals may not be detected at all, or multiple crystals may be detected without the risk of urinary stone formation.
Treatment
The presence of urinary stones in the urinary tract of dogs is not always associated with the development of clinical signs; in many cases, the presence of uroliths is not accompanied by any symptoms on the part of the animal. In the presence of uroliths, several scenarios may occur: their asymptomatic presence; evacuation of small uroliths into the spring environment through the urethra; spontaneous dissolution of urinary stones; growth cessation or continuation; addition of a secondary urinary tract infection (); partial or complete obstruction ureter or urethra (if the ureter is blocked, unilateral hydronephrosis may develop); formation of polypoid inflammation of the bladder. The approach to a dog with urolithiasis largely depends on the manifestation of certain clinical signs.
Urethral obstruction refers to emergency conditions, when it develops, a number of conservative measures can be taken to displace the stone either outward or back into the bladder. In females, rectal palpation with massage of the urethra and urolith towards the vagina can promote its exit from the urinary tract. In both females and males, the urethrohydropuslation method can push the urinary stone back into the bladder and restore normal urine flow. In some cases, when the diameter of the urolith is smaller than the diameter of the urethra, descending urohydropulsion can be used, when a sterile saline solution is injected into the bladder of an animal under anesthesia, followed by manual emptying in an attempt to remove stones (the procedure can be performed several times).
Once the stone has been displaced into the bladder, it can be removed by cytostomy, endoscopic laser lithotripsy, endoscopic basket extraction, laparoscopic cystotomy, dissolved by drug therapy, or destroyed by extracorporeal shock wave lithotripsy. The choice of method depends on the size of the animal, the necessary equipment and the qualifications of the veterinarian. If it is impossible to move the stone from the urethra, urethrotomy can be used in male dogs, followed by removal of the stone.
Indications for surgical treatment urolithiasis in dogs is indicated by such indicators as obstruction of the urethra and ureter; multiple recurrent episodes of urolithiasis; lack of effect from attempts to conservatively dissolve stones within 4-6 weeks, as well as the personal preferences of the doctor. When localizing uroliths in the kidneys of dogs, pyelotomy or nephrotomy can be used; it should be remembered that in dogs, uroliths of the kidneys and bladder can also be crushed using extracorporeal shock wave lithotripsy. If urinary stones are in the ureters and localized in the proximal areas, ureteretomy can be used; if localized in distal sections resection of the ureter can be used followed by creation of a new connection with bladder(ureteroneocystostomy).
Indications for conservative treatment of urolithiasis in dogs are the presence of soluble uroliths (struvite, urate, cystine and maybe xanthine) as well as animals with concomitant diseases increasing operational risk. Regardless of the composition of the urolith, general measures are taken in the form of increased water consumption (and therefore increased diuresis), treatment of any underlying diseases (eg Cushing's disease) as well as bacterial therapy (primary or secondary). It should be remembered that bacterial infection(cystitis or pyelonephritis) makes a significant contribution to the development of urolithiasis in dogs, either as a trigger or as a maintaining mechanism. The effectiveness of conservative dissolution of canine urinary stones is usually monitored by visual examination (usually x-ray).
With struvite urolithiasis, the main reason for their formation in dogs is a urinary tract infection, and they dissolve against the background of adequate antibacterial therapy, possibly with the combined use of dietary feeding. At the same time, the average time for dissolution of infected uroliths in dogs during treatment is about 12 weeks. With the sterile form of struvite urolithiasis in dogs, the time required for the dissolution of urinary stones is much shorter and takes about 4-6 weeks. In dogs with struvite urolithiasis, a change in diet may not be necessary to dissolve stones; reverse development of stones is observed only against the background of appropriate antibacterial therapy and increased water consumption.
In dogs with urate form of urolithiasis, in an attempt to conservatively dissolve stones, allopurinol can be used at a dose of 10-15 mg/kg PO x 2 times a day, as well as alkalinization of urine by changing the diet. The effectiveness of conservative dissolution of urates is less than 50% and takes an average of 4 weeks. It should be remembered that significant reason the formation of urates in dogs is, and the dissolution of stones can be observed only after surgical resolution of this problem.
For cystine uroliths in dogs, 2-mercatopropionol glysine (2-MPG) 15-20 mg/kg PO x 2 times a day can be used in an attempt to conservatively treat urolithiasis, as well as feeding an alkalizing diet low in protein. The dissolution time for cystine stones in dogs takes about 4-12 weeks.
Xanthine uroliths are treated by reducing the dose of allopurinol and a low-purine diet; there is a possibility of their reverse development. With oxalate uroliths, there are no proven methods for their dissolution and it is generally accepted that they cannot be reversed despite all the measures taken.
Valery Shubin, veterinarian, Balakovo
Portosystemic shunts (PSS) are a direct vascular connection portal vein with systemic circulation, so that substances with the portal blood are sent from intestinal tract bypassing the liver without hepatic metabolism. Dogs with pSS are very likely to develop ammonium urate uroliths. These uroliths occur in both males and females and are usually, but not always, diagnosed in animals over 3 years of age. The predisposition of dogs with pSS to urate urolithiasis is associated with concomitant hyperuricemia, hyperammonemia, hyperuricuria and hyperammoniuria.
However, not all dogs with pSS have ammonium urate uroliths.
Etiology and pathogenesis
Uric acid is one of several breakdown products of purine. In most dogs it is converted by hepatic urease to allantoin. (Bartgesetal., 1992). However, in pSS, little or no uric acid produced from purine metabolism passes through the liver. Consequently, it is not completely converted to allantoin, resulting in an abnormal increase in serum uric acid concentration. When examining 15 dogs with pSS at the University of Minnesota teaching hospital, the serum uric acid concentration was determined to be 1.2-4 mg/dL; in healthy dogs, this concentration was 0.2-0.4 mg/dL (Lulichetal., 1995). Uric acid is freely filtered by the glomeruli, reabsorbed in the proximal tubules and secreted into the tubular lumen of the distal proximal nephrons.
Thus, the concentration of uric acid in urine is determined in part by its concentration in serum. Due to northosystemic blood shunting, the concentration of uric acid in the serum increases, and, accordingly. in urine. The uroliths that form in pSS usually consist of ammonium urates. Ammonium urates are formed because the urine becomes supersaturated with ammonia and uric acid due to the drainage of blood from gate system directly into the systemic circulation.
Ammonia is produced mainly by bacterial colonies and is absorbed into the portal circulation. In healthy animals, ammonia enters the liver, and there it is converted into urea. In dogs with pSS, a small amount of ammonia is converted to urea, so its concentration in the systemic circulation increases. Increased concentrations of circulating ammonia result in increased urinary ammonia excretion. The result of portal blood bypass of hepatic metabolism is an increase in systemic concentrations of uric acid and ammonia, which are excreted in the urine. If the saturation of urine with ammonia and uric acid exceeds the solubility of ammonium urates, they precipitate. Precipitation under conditions of supersaturated urine leads to the formation of ammonium urate uroliths.
Clinical symptoms
Urate uroliths in pSS usually form in the bladder, therefore, affected animals will develop symptoms of urinary tract disease - hematuria, dysuria, pollakiuria and urinary dysfunction. With urethral obstruction, symptoms of anuria and post-nasal azotemia are observed. Some dogs with bladder stones do not have symptoms of urinary tract disease. Despite the fact that ammonium urate uroliths can also form in renal pelvis, they are very rarely found there. The PSS dog may have symptoms of hepatoencephalopathy - tremors, drooling, seizures, bleeding and slow growth
Diagnostics
Rice. 1. Microphotograph of urine sediment from a 6-year-old male miniature schnauzer. Urine sediment contains crystals of ammonium urate (unstained, magnification x 100)
Rice. 2. Double contrast cystogram
ma of a 2-year-old male Lhasa Apso with PSS.
Three radiolucent concretions are shown.
ment and a decrease in liver size. At
analysis of stones removed by surgery
chemically, it was revealed that they are
100% consisted of ammonium urate
Lab tests
Ammonium urate crystalluria is often found in dogs with pSS (Figure 1), which is an indicator of possible stone formation. Urine specific gravity may be low due to decreased concentration of urine in the nocturnal medulla. Another common disorder in dogs with pSS is microcytic anemia. Biochemical tests Serum levels in dogs with pSS are generally normal, except for low blood urea nitrogen concentrations caused by insufficient conversion of ammonia to urea.
Sometimes there is an increase in the activity of alkaline phosphatase and alanine aminotransferase, and the concentration of albumin and glucose may be low. Serum uric acid concentrations will be elevated, but these values should be interpreted with caution due to the unreliability of spectrophotometric methods for uric acid analysis. (Felicee et al., 1990). In dogs with pSS, the results of liver function tests will be increased serum concentrations bile acids before and after feeding, in increasing the concentration of ammonia in the blood and plasma before and after the administration of ammonium chloride and increasing the retention of bromsulfalein.
X-ray studies
Ammonium urate uroliths may be radiolucent. therefore, sometimes they cannot be identified on ordinary x-rays. However, an X-ray of the abdominal cavity can show a decrease in the size of the liver due to its atrophy, which was the result of portosystemic shunting of the blood. Rsnomegaly is sometimes observed in pSS; its significance is unclear. Ammonium urate uroliths in the bladder can be seen with double-contrast cystography (Figure 2) or ultrasound. If uroliths are present in the urethra, then contrast retrography is necessary to determine their size, number and location. When assessing the urinary tract, double contrast cystography and retrograde contrast urethrography have several advantages over abdominal ultrasound. Contrast images show both the bladder and urethra, but ultrasound scans show only the bladder. The number and size of stones can also be determined by contrast cystography. The main disadvantage contrast radiography urinary tract is its invasiveness, since this test requires sedation or general anesthesia. The condition of the kidneys can be assessed in terms of the presence of stones in the renal pelvis, but excretory urography is a more reliable way to examine the kidneys and ureters.
Treatment
Although in dogs without pSS it is possible to medicate ammonium urate uroliths with an alkaline low-purine diet in combination with allonurinol, drug therapy will not be effective in dissolving stones in dogs with pSS. The effectiveness of allopurinol may be altered in these animals due to the biotransformation of the short half-life drug to the long half-life oxypurinol. (Bartgesetal.,1997). Also, drug dissolution may be ineffective if uroliths contain other minerals in addition to ammonium urates. In addition, when allopurinol is prescribed, xanthine may be formed, which will interfere with dissolution
Urate urocystoliths, which are usually small, round and smooth, can be removed from the bladder using urohydropulsion during urination. However, the success of this procedure depends on the size of the uroliths, the diameter of which should be smaller than the most narrow part urethra. Therefore, dogs with pSS should not undergo this type of stone removal.
Since drug dissolution is ineffective, clinically active stones must be removed surgically. If possible, stones should be removed during surgical correction PSS. If the stones are not removed at this point, then hypothetically it can be assumed that in the absence of hyperuricuria and a decrease in the concentration of ammonia in the urine after surgical correction of pSS, the stones can dissolve on their own, since they consist of ammonium urates. New research is needed to confirm or refute this hypothesis. Also, the use of an alkaline diet with low purine content may prevent the growth of existing stones or promote their dissolution after ligation of psci.
Prevention
After ligation of the PSS, ammonium urate ceases to precipitate if normal blood flow passes through the liver. However, for animals in which PSS ligation cannot be performed, or where PSS is partially ligated, there is a risk of the formation of ammonium urate uroliths. These animals require constant monitoring of urine composition to prevent the precipitation of ammonium urate crystals. In case of crystalluria, additional preventive measures must be taken. Monitoring the concentration of ammonia in the blood plasma after feeding allows us to detect its increase, despite the absence clinical symptoms. Measurement of serum uric acid concentration also reveals its increase. Consequently, the concentrations of ammonia and uric acid in the urine of these animals will also be increased, increasing the risk of ammonium urate uroliths. In a study at the University of Minnesota, 4 dogs with inoperable pSS were treated with an alkalinizing, low-purine diet. (PrescriptionDietCanineu/d, Hill'sPetProduct, TopekaKS), which led to a decrease in the saturation of urine with ammonium urates to a level below their precipitation. In addition, the symptoms of genatoencephalopathy disappeared. These dogs lived for 3 years without recurrence of ammonium urate uroliths.
If preventative measures are necessary, a low-protein, alkalinizing diet should be used. The use of allopurinol is not recommended for dogs with pSS.
