Does the dog have CKD have positive outcomes? Renal failure in a dog: symptoms, stages, treatment and prognosis. Treatment and Diagnosis of Renal Failure in Dogs

Kidney failure in dogs is a fairly serious disease. And if your dog suffers from a similar disease, then you need to be well aware of this ailment in order to help your pet heal and continue a full life.

Symptoms of Kidney Disease in Dogs

Quite a severe disease is renal failure. The kidneys do not completely remove from the pet's body those substances that poison it. Phosphorus, calcium, vitamin D3 are poorly absorbed and the acid-base balance is disturbed throughout the body.

A number of infections and toxic substances cause kidney disease. The disease develops due to previous diseases, all kinds of injuries, and even because of low-quality products. This disease can be transmitted genetically. Age-related changes can also cause kidney failure. The concept itself means a disease not only of the kidneys themselves, but also of the adrenal glands too.

Certain symptoms indicate that your pet is suffering from kidney failure. Attention should be paid if

• The dog constantly drinks and suffers from endless thirst. During the day, the animal, having healthy kidneys, drinks up to fifty milliliters of fluid throughout the day. This is based on one kilogram of weight. In case of renal insufficiency, the dose of water consumed is increased to one hundred milliliters.
• Urine excreted by a dog, with a disease of renal failure, increases significantly in quantity. A dog can go to the toilet six to eight times a day. Over time, the kidneys no longer produce the required amount of urine. As a result, she doesn't stand out at all.
• Decreased appetite - may not be accidental. This is one of the most severe symptoms of this disease. At the beginning, the animal begins to sort out food. Then he does not eat even what is offered to him. Loses weight rapidly. As a result, the dog generally refuses to eat.
• Your friend has stopped frolicking. He doesn't care. He became lethargic, sleeps a lot or just lies. This condition of the animal may indicate that the dog is developing kidney failure.
• Vomiting is also one of the symptoms of this disease. At the onset of the disease, vomiting is rare. But over time, they become more frequent. Such a phenomenon can occur after each meal or just drinking water. The pulse quickens.
• Edema appears.
• The mouth becomes inflamed and ulcers appear.
• Vision drops sharply.
• Alternating indigestion and constipation.

Acute renal failure in dogs

The acute form of this disease has a distinctive feature: it develops extremely quickly. It is necessary to contact a specialist in time so that he makes the correct diagnosis. Under this condition, it is possible to cure this disease, as far as possible in each case, although this will require sufficient time. The difficulty lies in the fact that the acute form is quite rare. There are a number of factors that lead to the appearance of the disease.

• So nephrosis or nephritis entails the complete destruction of kidney tissue.
• Worms and the toxins they release lead to kidney disease. A variety of infectious diseases in dogs quite often entail AKI.
• There are a number of congenital diseases in which the kidneys do not cope with their immediate duties.
• It is possible that poisoning also causes this disease.
• A cyst in a dog interferes with the work of the kidneys. But after its removal, the body is restored completely.
• The tumor can provoke the appearance of the disease.
• One factor may be sand or a kidney stone.

The kidneys begin to work poorly if

OPN is divided into the following groups:

1. Prerenal.

At the same time, the pressure drops sharply. This is possible if there is not enough fluid in the body or during heat stroke.

1. Renal.

In the kidneys, tissues and cells are damaged. It can be caused by pyelonephritis, drug poisoning.

1. Postrenal.

In this case, the ureter is compressed, and possibly clogged. This means the presence of stones in the kidneys and ureters. OPN, if it is already secondary, becomes incurable.

Chronic kidney failure in dogs

Distinguish between acute and chronic renal failure in dogs. The acute form of renal failure is very fast in its development. And if you seek help from a specialist in time, who will quickly and correctly establish the diagnosis, you can help your pet. Chronic renal failure often occurs in dogs,

• who have lived for six years or more. But not only age can serve as the onset of the disease.
• It could be genetic heritage.
• And also OPN, formed much earlier.

The whole trouble is that the onset of kidney failure in a dog is not noticed by the owner of the dog for the simple reason that the disease does not have pronounced symptoms. And, therefore, no one is much alarmed. The first signs of CKD are:

• Bad appetite
• Weakness.
• The results of analyzes and certain tests indicate the presence of the disease.
• Increased thirst.

At the first stage of the disease, the dog remains active, frisky. The kidneys still cope with their functions and manage to purify the blood. This is facilitated by a large amount of urine. Further, the kidneys no longer cope with their duties and this entails a deterioration in the health of the animal. Clearly becomes noticeable:

• Weight loss,
• Endurance.
• The activity of the animal is lost.
• The dog drinks a lot.
• The excretion of urine becomes less and less every time. And there are false positives.
• The fur becomes dull.
• Saliva is viscous. Dehydration occurs.
• The temperature drops to thirty-seven degrees.
• There is bradycardia. The pulse rate is less than sixty beats per minute.
• The smell of ammonia comes from the dog's mouth.
• Periodically there are vomiting or vomiting. At the same time, undigested food is visible.
• Swelling of the extremities is quite common. Although this does not always happen.
• The kidneys gradually decrease in chronic renal failure.

The owner of a four-legged friend with such symptoms just needs to go to a specialist. After all, the pet urgently needs help.

Treating a disease in a dog

Renal failure in dogs can be difficult to diagnose early on because the kidneys are a paired organ. If one of the kidneys becomes ill, then the healthier kidney takes over its function for some time. And the body continues to work without any deviations.

Therefore, before proceeding with the treatment of kidney failure in a dog, the doctor will definitely prescribe a number of tests and examinations. In this case, the veterinarian will ask the owner about the living conditions of the dog, its usual behavior. And also to clarify what has changed in the behavior of the animal in recent years. The tests, x-rays, ultrasound examinations allow you to fully reveal the picture of the pet's disease. Based on this, the doctor makes an appointment.

Such a diagnosis requires inpatient treatment. For therapeutic treatment of acute renal failure and chronic renal failure, the same drugs are used. In the treatment of acute renal failure, the cause that led to the attack is eliminated. And with chronic renal failure, the goal is to maintain the vitality of a pet. With such a disease, the animal experiences severe intoxication. First of all, it must be eliminated.

• Intravenously, the animal is injected with a buffer composition, glucose, a physical solution in the form of droppers.
• In addition, the liver and heart are supported by certain drugs.
• Blood transfusion, if necessary, can sometimes also support the life of a pet.
• The use of an "artificial kidney" is also possible. But this will require very high costs.
• To improve the general condition of your pet and improve digestion, you need to take vitamins and probiotics.
• In addition, the doctor prescribes drugs to the caudate patient that can lower blood pressure, and pills or injections are also needed to calm the nervous system.
• To maintain health, a diet for dogs with kidney failure is very important.

It should be noted that the life expectancy of a pet depends on the stage of the disease, its type, as well as the conditions in which the animal is located.

What to feed a dog with such a deficiency

One of the conditions for the treatment of acute renal failure and chronic renal failure, as well as your desire to prolong the life of a pet, is nutrition. Properly selected and balanced selection of products will enable the four-legged friend to live a full and joyful life again. To do this, again, you need to listen to the opinion and advice of a specialist. At the same time, you can cook your own meals for your pet. And you can use special food for this purpose, buying it in specialized stores or veterinary pharmacies.

When choosing food for dogs with kidney failure, certain requirements must be met. But the most important requirement in cooking is a strict restriction of salt intake. It is salt that is the main enemy for those suffering from kidney failure. And if the pet is dear to the owner, then he will carefully adhere to this rule.

But fats in food should be in sufficient quantities. They are necessary to restore the vitality of your pet. The dog's diet should include eggs, butter, yogurt, which has a high percentage of fat content. But you should not use vegetable oil for cooking. When preparing meals at home, it must be remembered that fats should be introduced gradually and in small portions so as not to upset the work of the stomach and intestines.

Protein foods can not be completely excluded from the diet. But it still needs to be limited. You can give your pet two proteins and only one yolk for food. Egg shells can be included in the diet. Just before serving, it must be finely chopped. This use of the shell will allow the absorption of phosphorus. For half a kilogram of any cooked food, you need only one gram of crushed eggshell.

Consumption of dairy products

With some caution and in small quantities, it is necessary to introduce milk and products containing milk, bones. The amount of foods that contain phosphorus directly depends on the severity of the disease. The more difficult the degree of the disease, the less phosphorus should be in the diet of the animal.

Carbohydrates, which have a low amount of phosphorus, should also be used when feeding a dog suffering from kidney failure. You can cook dishes using semolina and rice, as well as white potatoes.

Another very important factor in dietary nutrition is water. Tap water should never be used for cooking, especially for an animal suffering from kidney failure. Therefore, water is taken for culinary products and just for drinking, only filtered.

If your pet does not want to eat, then it is better to cook for him those dishes that he likes. Treat your pet with tasty treats. As the dog recovers, he will eat whatever is offered to him.

There are special dry food for dogs () suffering from kidney diseases. And their range is quite diverse. But before you buy such food, you need to make sure it suits your pet.

It is worth knowing that transferring a dog to a normal diet is possible only after certain treatment and tests, with the permission of a doctor. This is possible if a four-legged friend is diagnosed with acute renal failure. In chronic renal failure, dietary nutrition is constantly observed and cannot be abandoned. If older dogs suffered from kidney failure in a dog in the old days, now PN has become younger. And many younger pets suffer from this disease. Take care and love your pets.

Which manifests itself with a violation of their main function - filtration. In other words, for certain reasons, the kidneys cannot remove toxic substances from the blood that are formed during the life of the body. Because of this, a kind of poisoning occurs.

The kidneys perform many functions in the dog's body. This is the cleansing of harmful substances, the removal of fluid from the body, the production of certain hormones, and the maintenance of stable blood pressure. In addition, the kidneys are involved in the exchange of phosphorus, calcium, vitamin D3, maintain the nutritional status of the body and its acid-base balance.

The causes of kidney problems can vary. These include the entry into the body of infection, toxic substances. Also, kidney failure can be provoked by various injuries, previous illnesses, or simply poor-quality products. Some dogs succumb to kidney failure due to changes in age or because of a genetic predisposition.

Kidney failure can take two forms: acute and chronic. The first occurs due to shock, the toxic effects of toxic substances, the intake of certain drugs. Functional disturbances manifest themselves quite acutely. The acute form is less dangerous than the chronic one, since the possibility of recovery is not excluded.

Doctors divide acute renal failure into several groups:

1. prerenal - develops as a result of shock that arose from various sources with a drop in blood pressure and a violation of blood circulation inside the kidneys;
2. renal - occurs and develops in the presence of infections, inflammatory processes in the kidneys due to the direct effect on the tissues of the kidneys of certain substances and drugs;
3. postrenal - appears after urolithiasis, with squeezing or even blockage of the urinary tract.

The chronic form occurs and manifests itself for a long time. In this case, the process of constant death of nephrons occurs. Interestingly, for some time, still living cells take on tasks and completely replace the dead ones. And only when 23 or more kidney tissues are affected, they begin to identify and show signs of the disease.

This stage is difficult to treat, if at all. The maximum that can be done is to keep the dog's kidneys alive through many different procedures.

Symptoms of Kidney Failure in Dogs

Chronic renal failure is a serious disease. It is accompanied by increased thirst, a decrease in temperature, depression of the general condition of the body, dehydration, an unpleasant smell from the mouth, and vomiting. Urination either drops sharply or disappears altogether.

In the acute form, the animal, in addition to the above circumstances, also becomes less active. The dog gradually moves less, sleeps more.

Symptoms that are noticed almost immediately include the dog's extreme thirst and frequent urination. To distinguish this symptom from a normal condition, you need to remember that a healthy dog ​​needs 50 milliliters of water for every kilogram of weight. With kidney failure, the amount of water taken by her increases at least twice.

Vomiting may not appear at first, but over time the dog eats less and less and reluctantly, sometimes vomiting occurs, which then repeats more often.

The doctor diagnoses kidney failure based on data on the condition of the animal, as well as on the results of the tests performed. One of the decisive parameters in the diagnosis is the amount of urine. The urea of ​​a diseased dog may contain urea and creatine, the level of acidity and phosphorus in the blood increases. When analyzed in the urine of a pet, protein, glucose, and fiber of the epithelial integument of the kidney can also be detected.

In addition to general tests, X-ray diagnostics are also carried out, including the introduction of certain special substances into the blood, less often ultrasound diagnostics or biopsy.

Treatment of kidney failure in dogs

The main direction of treating a dog for kidney failure is to eliminate the causes, correct the imbalance of fluid and electrolytes, stimulate diuresis, and remove toxins from the body. Therefore, sick pets are often prescribed intensive care. It is the elimination of causes that plays a huge role. Because it can solve several problems at once.

To correct the water-electrolyte, acid-base balance, infusor therapy is carried out. It is carried out until the content of urea and creatine is normalized, and the general condition is not stabilized. During treatment, it is important to ensure that important functions of the pet's body are not violated.

If the form of insufficiency is chronic, irreversible pathological changes occur in the kidneys. Conducting in this case the same as in the acute form of treatment will not be enough. You need peritoneal dialysis. This procedure is carried out only in the clinic.

It can be concluded that in any case, even with the mildest manifestations of the disease, you need to contact a veterinarian, in no case should you treat yourself, because even with the provision of timely professional assistance, the animal may die due to irreversible damage.

Help treatment can be paying attention to the nutrition of the dog. In a state of illness, it is very important that the animal receives the right amount of nutrients. If the pet has not lost its appetite and eats well, it will be enough just to add special dietary feeds to the diet. You can also enter a diet, the main condition of which is a decrease in the amount of phosphorus, sodium and protein.

With a complete lack of appetite and no vomiting, the animal is fed with a probe. If vomiting is still present, the necessary substances can be administered intravenously.

But it is better to take care of the animal and not allow its health to deteriorate so much. The life of a pet often depends solely on the actions of the owner, and the responsibility also lies with him.

Kidney failure, which our most beloved dogs often fall ill with, is considered the most dangerous, severe kidney disease, manifested by impaired filtration (the main function of the kidneys). In other words, taking into account various reasons, the kidneys are not able to remove poisonous substances that are dangerous for its body, which are formed during the life process of the body, from the blood of an animal. Immediately after the kidneys cease to function normally, poisoning is observed in dogs.

kidney failure- one of the most dangerous diseases, often leading to the death of pets. This problem has recently gained such an extensive turn that veterinarians are interested in it closely.

I would like to immediately emphasize that such a disease as kidney failure does not exist in general either in animals or in humans: it is a series of external manifestations of a number of kidney diseases. Kidney failure, like in humans, in dogs is caused by various reasons, but the general symptomatology still exists - the kidneys work very poorly, and ultimately, if they are not treated, they fail, the dog dies.

Causes of the disease

Cause of kidney failure:

• An infection that has entered the body of a dog from the outside.
• Toxic substances from the environment.
• Injury and disease once suffered by a dog.
• Bad foods high in salt.
• Age changes.
• genetic propensity.

Symptoms of kidney failure

For dogs, kidney failure is quite serious illness accompanied by intense thirst. Consider the fact that a healthy dog ​​(per kilogram of weight) consumes up to fifty milliliters of water per day. A sick dog consumes 2 times more liquid. Also, the dog's body suffers from dehydration, a sharp decrease in temperature, an oppressed general condition of the animal's body is observed, an unpleasant, sour smell often comes from the mouth, the dog often swears and vomits. Vomiting does not immediately manifest itself: at first, the animal begins to eat little, then eats food reluctantly and intermittently, and then stops eating altogether, because vomiting is observed after each meal. Also, the dog may have frequent urination or vice versa, with a long delay.

If a dog's kidney failure has passed into an acute stage, the animal generally ceases to show any signs of activity: it does not play, does not jump, but only eats a little and sleeps a lot.

The diagnosis of "renal failure" is made by the veterinarian only after he has carried out all the necessary studies. Having received the results of the tests and all the data on how the animal feels, the doctor prescribes the appropriate treatment. Urinalysis is very important in this aspect. The urine of a dog with kidney failure contains a nitrogen-containing carboxylic acid (creatine) and phosphorus. Poor dog urine analysis - significant protein content, excess glucose. In addition to urine analysis, the veterinarian may additionally prescribe an ultrasound, x-ray and biopsy.

Stages of disease development

Kidney failure in a dog does not just happen. It is a consequence of the above reasons and is divided into stages, each of which is too significant not to pay attention to it.

There are two common stages of kidney failure, and both are very dangerous: acute stage: toxic effects on the body of too toxic substances used by the dog; shock, taking poisonous, chemical drugs in the treatment of other diseases of the animal. The acute stage of kidney failure in dogs is not as dangerous as chronic, after all, it is possible to completely cure the dog in the acute stage, while in the chronic form, the disease "renal failure" is no longer curable.

The acute form of renal failure is divided by veterinarians into the following stages:

• The stage of compensation, which takes up to ninety percent of the time of development of this disease. At this stage, the dog does not manifest itself in any way, as usual, frolics, sleeps and eats well. But ... if an observant owner smelled the unpleasant smell of urine, noticed, if the opportunity presented itself, an unusual consistency and color of urine, passed it for analysis to a veterinary clinic, the doctor will very quickly identify the disease.
• The disease has not yet manifested. Significant morphological and functional disorders gradually increase in the tissues of the kidney, although one should not be afraid of a sad outcome. Having passed the dog's urine for analysis to a veterinary clinic, you can find out that the dog has kidney failure, but without a biochemical analysis of the animal's blood, the veterinarian will not be able to tell the owner about the stage. An additional diagnostic ultrasound examination by a highly qualified veterinarian will not be superfluous.
• Decompensation. The dog is in a very bad condition, and the owner himself notices this. The dog is still drinking and eating, but is less active and joyful than before. Urinalysis is mandatory.
• Terminal (most dangerous) stage. The kidneys are failing, and the day is not far off when it is already possible to say goodbye to the dog, as it is overcome by a renal coma.

I would like to note that a veterinarian can make a diagnosis of "acute renal failure" without problems if modern advanced diagnostic equipment is installed in his clinic. If you love your pet, never think about money and time while watching your pet friend misbehave for a couple of days. Take him to the veterinarian and make timely diagnostics and tests to save his life.

Treatment of the disease

Treatment for kidney failure in dogs includes :

• intensive infusion therapy with sorbilact, special solutions, reosobilact, with the help of Ringer-Locke, a salt-based plasma-substituting liquid;
• the use of dopamine, lespenephril, mannitol and lasix;
• enterosorption therapy. The dog should be given Canephron, Belosorb-P and Heptral;
• diet low in protein;
• homeopathic therapy: give Solidago compositum C

Prevention of kidney failure

Prevention of this disease is based, first of all, on providing the animal with proper nutrition. If the dog still has an excellent appetite and eats well, we recommend supplementing his diet with diet food and a protein diet.

An excellent modern remedy for the treatment of renal failure in animals, the renal diet is the basis of advanced medical treatment for pets at any stage of the disease. This renal diet helps to prevent or even significantly reduce uremia during the acute stage, restore electrolyte balance, and prevent the chronic form from developing rapidly. In recent studies, it was found that the kidney diet (food) that is added to the daily diet of dogs significantly prevents the risk of kidney disease in dogs.

Renal failure in dogs frequent disease mainly in old age.

With timely diagnosis, it is usually possible to maintain a good quality of life for dogs for a long time.

Kidney failure (RI) - definition

Renal failure in dogs This is a condition in which the kidneys cannot cope with the functions of excreting toxins and maintaining the body's water balance. As a rule, signs of disorders become noticeable after the loss of 70 - 80% of renal tissue.

Principles of treatment

Diagnosis of kidney failure in dogs

The diagnosis is made on the basis of biochemical and general blood tests, urinalysis, determination of CFP, abdominal ultrasound, blood pressure measurements. Diagnosis of kidney failure

Determination of kidney function in percent

This analysis allows for early diagnosis of kidney function and to make a prognosis with an already developed disease.

Acute renal failure in dogs

AKI is a sudden cessation or a sharp decrease in the function of healthy kidneys, which, with timely and proper treatment, can result in a complete recovery. Acute renal failure

Chronic renal failure in dogs

CRF is a slow decline in kidney activity until complete disappearance, caused by the gradual death of kidney tissue as a result of chronic kidney disease. Chronic renal failure

Exacerbation of chronic PN

In veterinary practice, exacerbation of chronic renal failure is most common. Exacerbation of chronic renal failure

Causes

Congenital (genetically determined) and acquired (infectious diseases, consequences of hypothermia, poisoning).

Treatment of kidney failure

1. Impact on the cause of the disease, in cases where it is possible (hormones, antibiotics).

2. Cleansing the body of toxins (forced diuresis, intestinal dialysis, extracorporeal methods of blood purification).

3. Maintaining the vital functions of a sick organism (dietary nutrition, control of cardiac activity, prevention of bleeding in the gastrointestinal tract, regulation of mineral metabolism).

PN treatment - for pet owners.

Treatment of renal failure - information for physicians.

Questions and answers

Checklist for general questions about renal failure in animals.

MAIN PROVISIONS

• Chronic renal failure (CRF) is the most commonly diagnosed kidney disease in dogs.
• Clinical signs of the disease appear only after at least 67% of the renal parenchyma ceases to function.
• Diagnosis of early stages of impaired renal function allows timely use of protection techniques, incl. transfer the animal to a special diet and prescribe appropriate drug therapy in order to slow down the development of further lesions of these organs, speed up recovery and improve the quality of life of the animal.
• The plasma clearance test for exogenous creatinine can be used in routine veterinary practice.

Chronic renal failure (CRF) is the most commonly diagnosed kidney disease in dogs. It develops as a result of the progressive and irreversible loss of functioning nephrons. Clinical signs of renal failure begin to appear when 67-75% of the renal parenchyma ceases to function. Polyuria and polydipsia are usually the first signs of kidney disease, but they are often overlooked for a long time. It is generally accepted that a decrease in the specific gravity of urine and azotemia (i.e., the excess of the concentration of creatinine and / or urea of ​​the permissible norm) occurs only after the failure of at least 67% and 75% of the renal parenchyma, respectively (Fig. 1). Therefore, CKD is usually diagnosed at a relatively late stage of kidney disease. Over the past 20 years, significant progress has been made in diet therapy and drug treatment of chronic renal failure, but the problem of its early diagnosis is still relevant. Establishing a violation of kidney function at the very beginning of the disease makes it possible to use means to protect these organs from further damage, incl. prescribe a special diet or drug therapy. This will slow down the development of kidney disease, shorten the recovery period and improve the quality of life of sick animals. This publication describes a number of strategic approaches to the detection of renal dysfunction in dogs with subclinical CKD.

Figure 1. The consequences of kidney disease and the development of uremic syndrome with it.

Informing and educating pet owners, identifying risk factors

CRF is frequently reported in dogs. Therefore, every dog ​​owner should be informed about chronic renal failure, its prevention, manifestations of diagnostic significance, as well as factors contributing to the development of this pathology. Particular attention should be paid to dog breeds that show a predisposition to kidney disease. It is important to reassure breeders that kidney problems can occur even in clinically healthy dogs. Owners should be advised to monitor their pets on a regular basis so that they can judge whether the disease is progressing or not and seek timely help from specialists for further examinations. Well-informed breeders can provide very important information about their pets' water and food intake, as well as changes in animal body weight.

Risk factors associated with the development of CKD in dogs are poorly understood, but apparently this pathology is most often manifested in adult animals of this species: 45% of dogs with CKD are over 10 years old. This does not mean that any adult dog can get sick, but suggests the need to determine the concentration of creatinine in the blood plasma and specific gravity of urine (URG) in animals as the most important indicators of the health of aging animals. Hereditary nephropathies have been reported in some dog breeds (Table 1), although their incidence remains unknown. These hereditary diseases can develop in puppies, young, adult and aging dogs. If it is suspected that dogs of these breeds have impaired renal function, it is necessary to collect anamnestic data on whether such a disease has occurred in animals of this line (in parents, littermates, other relatives). CRF can be caused by various reasons, and the establishment of any of these etiological factors (for example, according to anamnestic data that the animal had had piroplasmosis, hypertension, etc. in the past) (Fig. 2) should serve as a reason for kidney studies.

Figure 2. Causes of Acquired Chronic Renal Failure

Regular assessment of animal water intake, diuresis, appetite and body weight

Polyuria and polydipsia resulting from loss of the ability to concentrate urine are not specific to CKD but are considered early clinical manifestations. It can be difficult for owners to determine how much urine their dogs produce. To accurately determine this indicator, the animal is hospitalized and placed in a metabolic chamber for a day (usually this is used for experimental purposes, and not for routine diagnostic examinations). Before being placed in the chamber and before being released from it, the animal is made to perform the act of urination. An adult dog excretes approximately 20-40 ml/kg of body weight of urine during the day (in puppies this figure is higher).

Assessing a dog's water intake is much easier, especially when the animal's access to water is controlled. Owners of dogs at high risk for CRF are advised to conduct an annual control determination of their pets' water intake. This indicator is considered normal if it does not exceed 100 ml / kg of body weight. The volume of water drunk daily by animals is variable, as it depends on a number of factors, incl. physical activity, air temperature, type of diet, etc. Therefore, the measurement of the amount of water consumed by the dog is carried out for 3-4 days in a row. To avoid subjectivity in determining this indicator, the dog owner needs to weigh a bowl of water 2 times a day (with an interval of 24 hours).

Some decrease in appetite and body weight, although not specific to CRF, often accompanies this pathology. Daily feed intake is estimated by weighing it at each giving to the animal. When changing diets, an animal's appetite may change depending on how attractive the new food is to them. Weighing animals is less subjective, but should be done regularly and on the same scales.

Indirect assessment of kidney function based on the results of repeated studies of blood plasma and urine

This article discusses the possibility of diagnosing CRF only in those animals in which this pathology is asymptomatic or manifests itself with mild clinical signs. The best markers of kidney function in this situation are creatinine and urine specific gravity.

Plasma creatinine concentration

Creatinine is constantly produced in the muscles as a result of creatine metabolism. It is excreted from the body only in the urine, being completely filtered in the kidneys through the glomeruli and only slightly secreted in the renal tubules. Plasma creatinine concentration is considered the best indirect indicator of kidney function, although many factors influence the accuracy of its determination.

In this regard, it is impossible to discount the influence of various factors acting before taking the analysis and during its implementation. Blood samples for its implementation should be taken from animals on an empty stomach (a 12-hour overnight fast is enough). Most foods contain some creatinine, so after taking them, dogs can experience an increase in its blood concentration above the acceptable level, which causes non-specific test readings. Physical activity does not lead to a significant change in the concentration of creatinine in the blood plasma in dogs. Plasma creatinine concentration is better determined by the enzymatic method, and not by the Jaffe method, since the indications of the latter are influenced by an increased (> 50 μmol / l) concentration of bilirubin in the blood.

Figure 3. Dependence of plasma creatinine concentration and glomerular filtration rate (GFR) is graphically expressed by a curved line. This indicates an early stage of renal dysfunction, manifested by a decrease in GFR and a corresponding slight change in plasma creatinine concentration. In contrast, dogs with severe renal insufficiency show significant fluctuations in plasma creatinine levels, with relatively limited fluctuations in GFR.

It is believed that an increase in the concentration of creatinine in the blood plasma indicates a decrease in the functional state of the kidneys. The dependence of this indicator and GFR is graphically depicted by a curve (Fig. 3). Meanwhile, the concentration of creatinine in blood plasma depends on a combination of factors such as the formation, distribution and excretion of creatinine from the body. This means that this indicator can be increased in dogs with developed muscles or suffering from dehydration. In animals with renal insufficiency, endogenous creatinine production is reduced (2). As a consequence, elevated plasma creatinine does not necessarily correlate with GFR, as creatinine production can also be reduced as a result of decreased muscle mass. Dehydration can lead to a decrease in the volume of distribution of creatinine, which depends on the total body water supply. However, dehydration usually occurs only in the later stages of CKD.

A once determined concentration of creatinine in the patient's blood plasma is usually compared with the maximum allowable value of this indicator. If the concentration of creatinine in the blood of the animal is higher than the latter, then the presence of kidney pathology is assumed, and if it is below the permissible level, then the animal is considered healthy. But in some situations this approach is wrong. Literature data on the permissible value of such an indicator are very variable (Fig. 4), which is partly due to the characteristics of the populations of dogs in which blood testing was performed, its dependence on age, breed, and a number of other factors. In dogs of different breeds and animals of different ages, the normal concentration of creatinine in the blood is not the same. For example, it is higher in adult dogs compared to puppies, as well as in breeds of dogs with more developed muscles. Therefore, one should be very careful in interpreting a slight excess of this indicator of the norm. Impaired renal function can also occur in cases where the concentration of creatinine in the blood plasma remains within the normal range.

Figure 4. Various allowable values ​​for canine plasma creatinine levels (according to veterinary guidelines or from Reflotron, Kodak and Vettest analyzers). There are significant discrepancies between data obtained from different sources, which may be due to differences in control samples or methods of analysis

Nevertheless, even the results of a single determination of the concentration of creatinine in blood plasma provides valuable diagnostic information, on the basis of which the International Renal Interest Society has recently proposed a classification of stages of CRF in dogs and cats, based on the value this indicator (table 2).

Significantly more accurate readings are obtained by serially determining the concentration of creatinine in the blood plasma in a dog for some time (for example, one year). At the same time, it is important to standardize the conditions for testing in order to to avoid the influence of factors that complicate the interpretation of the results. So, for example, blood should be taken from the dog on an empty stomach each time, the same testing method should be used, and the body condition of the animal should not change throughout the entire study period. Blood plasma samples are stored until the study is frozen (at a stable temperature not exceeding -20°C). When it is time to study the next blood plasma sample, the one taken the previous time is thawed and examined simultaneously with the last one. This establishes a "critical change" in the measurable index, which is the minimum difference between two consecutive levels of plasma creatinine concentration and reflects biologically significant changes in kidney function in healthy dogs. dl).

When a dog suddenly develops significant changes in the concentration of creatinine in the blood plasma, their relationship with the state of health of the animal is checked by a repeated study, which makes it possible to exclude diagnostic errors (Fig. 5).

Figure 5. Variation in plasma creatinine due to analytical errors. From the blood plasma samples of the dogs, they were blinded twice in the same laboratory. Very large discrepancies in the results of testing one sample were obtained - 0.7 (62 µmol/l) and 2.1 mg/dl (186 µmol/l). These observations indicate the need to re-examine serum samples in cases of unexpectedly high or low readings compared to previous plasma results from the same animal.

Specific Gravity of Urine (SPM)

TPM is the ratio of the mass of a certain volume of urine to the mass of the same volume of pure water at the same temperature. UPM is determined using a refractometer. Changes can occur already at the initial stage of renal failure. However, TMR - highly variable even in healthy dogs - can change with the animal's water intake and diet. The TFR also varies from day to day, from one sample to another. When the body is normally hydrated, the BMR usually ranges from 1.015 to 1.045, but can decrease to 1.001 or increase to 1.075. If the TMR rises above 1.030, the dog begins active resorption of water from the renal tubules and collecting ducts of the kidneys. With a decrease in the UPM below 1.008, the animal begins the resorption of salts from the filtrate located in the renal tubules. In both cases, the kidneys compensate for these changes. When determining the TMR, the degree of hydration of the animal's body is taken into account: too low TMR (<1,030) на фоне обезвоживания организма указывает на первичную дисфункцию почек или другие причины, повлекшие за собой снижение концентрирования мочи. Однако возможна и такая ситуация, когда при обезвоживании организма у собаки с субклиническим нарушением функции почек УПМ оказывается выше 1.030. Из-за вариабельности УПМ однократно выявленные изменения этого показателя не обязательно указывают на полиурию, но критериями последней служит персистентное значение УПМ в пределах от 1,008 до 1,029. Сопутствующая азотемия дает больше оснований подозревать наличие заболевания почек, но не позволяет поставить окончательный диагноз.

Other indicators

Plasma urea (or "blood urea nitrogen") concentration is also important in the diagnosis of clinical CKD. A number of researchers believe that this indicator correlates better with the clinical signs of the latter than the concentration of creatinine in blood plasma. However, plasma creatinine seems to be a better reflection of GFR decline than blood urea, due to the presence of many extrarenal factors that can affect the value of the latter indicator. These factors include feeding and starvation, metabolic activity of the liver, dehydration, etc. Therefore, the concentration of creatinine in the blood plasma is more important for diagnosing the early stage of impaired renal function and the latter in subclinical cases.

Electrolyte disturbances (hyperphosphatemia, hypokalemia, hypocalcemia) are noted during a period of significant impairment of kidney function, but they are absent in the early subclinical stages.

Proteinuria can develop at any stage of CRF. and its intensity is largely determined by the etiology of the disease. When proteinuria is detected, additional studies are necessary to establish the cause of the disease. However, in many animals with CRF, proteinuria is mild.

Testing the ability of the kidneys to concentrate urine

With chronic renal failure, the ability of the kidneys to concentrate urine decreases, but other factors also influence the value of the ULR, incl. treatment with diuretics and glucocorticoids, glucosuria, diabetes insipidus, imbalance of basic electrolytes. The test, based on the restriction of the dog in water, allows you to evaluate the concentrating activity of the kidneys in polyuria or polydipsia without determining their causes. It should not be used to examine dogs suffering from dehydration and/or azotemia, as its administration in such cases is associated with the risk of harm to the health of animals and since dehydration in patients with low TLR is itself evidence of the loss of the ability of the kidneys to concentrate urine. This test can be carried out in two versions (table 4). However, its sensitivity in the diagnosis of early stage CKD has not been documented.

Direct method for determining GFR

GFR is currently considered the best direct indicator of kidney function. Over the past 30 years, many new methods for determining this indicator have been proposed and tested, based on determining the clearance of certain markers in urine and blood plasma from the corresponding marker.

Urine and plasma clearance, application restrictions

Determination of inulin clearance in urine is considered a reference method for assessing GFR. The calculation is simple, and for its implementation it is necessary to know only three indicators: the volume of urine excreted by the animals for a certain period, as well as the concentration of the marker in the urine and blood plasma. Despite providing valuable diagnostic information, urine clearance tests are rarely used in veterinary practice, because they are time consuming and labor intensive. In addition, it is necessary to collect urine at a certain time, and in the process of frequent catheterization, the risk of injury and infection of the urinary tract of animals increases. While the dog is in the metabolic chamber, urine collection can be limited to 24 hours, but there is a need for repeated washings of the chamber to maximize the collection of the marker, the remains of which in subsequent tests can cause an incorrect determination of clearance.

For these reasons, tests designed to determine plasma clearance (especially those involving a single intravenous administration of a marker) are considered an alternative to appropriate urinalysis in cases where urinary excretion of the marker is negligible. The main advantage of the test, which determines GFR by its clearance from blood plasma after a single intravenous injection of a marker, is that only one blood sample is required to obtain a result. Radiopaque agents (eg, iohexol and iothalamate), inulin, various radioactively labeled substrates, and creatinine are used as markers. These tests have a number of limitations. For example, radioactively labeled nucleotides cannot be used in routine diagnostic practice due to safety and legal restrictions. Detection of most of the available markers is difficult, costly, or simply out of the reach of the conventional veterinary practice. The iohexol test requires a rather large volume of blood plasma (3-4 ml, i.e. approximately 8 ml of blood), which is too much for small breed dogs. This marker is detected by a specific fluorescent glow in x-rays. Finally, when determining plasma clearance, which is the ratio of the dose of the marker administered to the animal and the area under the curve of its plasma concentration (AUC) over time, complex calculations are required (data modeling using exponential equations), which discourages veterinary practitioners from its application.

Plasma clearance test for exogenous creatinine (ECPEC)

TCPEC was developed recently and tested on dogs in comparison with known methods for assessing GFR (tests to determine the clearance of inulin and endogenous creatinine in the urine, blood plasma from iothalamate). Plasma and urine clearance from creatinine is consistent with GFR in dogs. With its help, it is possible to diagnose subclinical kidney dysfunction in this animal species. The main advantage of TCPEC is the ability to determine the baseline plasma creatinine concentration, which provides a direct estimate of GFR, regardless of the volume of distribution and endogenous production of creatinine.

The main stages of the TCPEC

> Determination of fasting baseline (initial) plasma creatinine concentration before the test.
> Intravenous administration of a certain amount of creatinine.
> Determination of plasma creatinine concentration.

Calculation of blood plasma clearance.

The main advantages of TKPEC:

> The test can be performed in normal veterinary practice because it is simple, easy to perform (intravenous marker injection and blood sampling) and time-consuming.
> Only 1 ml of blood is needed to obtain a result, which makes it possible, if necessary, to re-sample blood from small breed dogs or puppies, and, in addition, limits the number of manipulations performed on the animal.
> Creatinine is safe: an increase in the plasma concentration of creatinine in CRF dogs after intravenous administration to 8000 µmol/l (90 mg/dl) does not lead to undesirable side effects.
> There is no need to resort to the services of specialized laboratories, because Plasma creatinine concentration can be quickly determined using a conventional veterinary chemistry analyzer.
> The results of the test are received immediately after it is set.
> Determination of creatinine clearance does not require complicated calculations
> TCPEC does not require large financial outlays.

There are no commercial preparations of creatinine - they have to be prepared independently, although preparations are underway for the production of this reagent.
- The last blood sample must be taken from dogs for examination no later than 6 hours after administration of creatinine. Therefore, the dog has to be hospitalized for the whole day during the test.
- Limits of normal GFR values ​​for dogs have not been definitively defined. Currently, the maximum allowable value of this indicator is 1.5 ml / kg / min, but the results of further studies may make their own adjustments.

Conclusion

The fight against CRF is one of the main problems in ensuring the health of small domestic animals. Currently, its early diagnosis is difficult, because in the initial stages of chronic renal failure is asymptomatic. However, a number of useful actions can be taken in this direction: informing pet owners about this pathology, regular examination of their pets, including determining changes in TLR and plasma creatinine concentration in their blood over time, and assessing GFR (if available in this need). The main hope is that early diagnosis of CRF will help to start treating a sick animal in a timely manner and transfer it to a special diet, which will both prolong the patient's life and improve its quality.

Herve P. Lefebvre
Herve P. Lefebvre, DVM, PhD, Dipl ECVPT, Professor of Physiology
Jean-Pierre Bron
Jean-Pierre Braun, DVM, PhD, Dipl ECVCP, Professor of Biochemistry, Physiology and Therapy, Department of Pathophysiology and Experimental Toxicology, National Veterinary School in Toulouse, France
A. David J. Watson
A. David J. Watson, BVSc, PhD, FRCVS, FAAVPT, MACVSc, Dipl ECVPT,
Associate Professor of Veterinary Medicine, Department of Veterinary Sciences, University of Sydney, Australia