Kidney failure means that the cat’s kidney (s) are no longer functioning properly and are no longer able to perform their functions. It is important to know how to distinguish acute renal failure from chronic renal failure. In any case, if you have the slightest doubt about your cat’s health, do not hesitate to contact your veterinarian.

To understand what kidney failure is, it is important to have in mind how the kidney works. The main role of the latter is to filter the body’s blood in order to produce urine (which contains blood waste) but above all to maintain the composition of the blood stable. It also allows the synthesis of certain hormones. The nephron is the functional unit of the kidney. Each kidney has several hundreds of thousands of them and it is these which ensure the role of filtration. In the event of renal failure, the filtration is no longer done correctly because some nephrons are damaged. As they are not all functional, the filtration is poorer.

In cats, acute renal failure (AKI) is often reversible and occurs quickly, unlike chronic renal failure (CKD) which begins gradually and is irreversible.

Many causes can be at the origin of an ARI such as hemorrhage, ingestion of a toxic substance (for example a plant) or an obstacle to the flow of urine. We can then observe a sudden attack on the general condition of the cat (vomiting, diarrhea, dehydration or even a state of shock depending on the cause) or even difficulty in urinating.

It is important to keep in mind that an ARI can represent an emergency, so you must quickly take your cat to your vet for treatment.

Chronic renal failure means that the kidneys are gradually damaged and irreversibly damaged for at least 3 months. 

Several warning signs should make you think about taking a consultation with your veterinarian and in particular this one:

• Polyuro-polydipsia: the cat urinates more abundantly and drinks more water. It is the first sign of calling to know how to recognize. Indeed, when nephrons are damaged, the other functional must ensure a greater filtration load increasing the volume of urine. In addition, the kidney can no longer concentrate the urine which is thus diluted (very light yellow urine). To compensate for this loss of water in the urine, the cat will drink more. However, this is difficult to see in cats, especially those that live outdoors.

The following clinical signs appear in advanced stages when the kidneys are severely damaged:

• Weight loss;
• Loss of appetite ;
• Dull coat;
• Possible vomiting;
• Dehydration.

Diagnostic

Your veterinarian will carry out a thorough examination of your animal with additional examinations (blood test for analysis, palpation of the kidneys, urine analysis, imaging, etc.) in order to confirm or not a renal failure and to determine the cause. Depending on the kidney damage and the results of the analyzes, an IRIS (International Renal Interest Society) classification was set up in order to assign a clinical stage to the cat. Indeed, a blood test will make it possible to determine how the filtration of the kidneys works, in particular thanks to the levels of creatinine, urea and SDMA (Symmetric DiMethyl Arginine, an amino acid) present in the blood. These substances are wastes normally excreted in the urine. As soon as the filtration is no longer correct, they will accumulate in the blood. The higher their quantity, the worse the filtration and therefore the more damaged the kidney.

Thus, in cats, there are the following 4 IRIS stages:

• Stage 1: normal creatinine level, no symptoms, SDMA level may be slightly higher;
• Stage 2: creatinine level normal or slightly higher than normal, possible presence of mild symptoms, slightly higher SDMA level;
• Stage 3: creatinine and SDMA levels higher than normal, presence of renal symptoms (polyuropolydipsia) and general (loss of appetite, vomiting, weight loss, etc.);
• Stage 4: very high creatinine and SDMA levels, the cat is in the terminal phase of CRF and has severe damage to its state of health.

It is important to keep in mind that the more advanced the stage, the poorer the prognosis. Usually, symptoms do not appear until late, when the kidney is very weak, because in the early stages the kidneys are able to compensate for the progressive loss of nephrons.

The drug treatment implemented will depend on the stage of the cat as well as the symptoms it presents. In the most serious cases, especially in cases of dehydration, hospitalization may be necessary.

The main treatment is a change in diet. It is therefore necessary to switch to a therapeutic diet specially designed for cats with renal failure by making a gradual dietary transition. Indeed, this diet will allow him to preserve his kidneys and increase his life expectancy. In addition, it is important to always give the cat fresh and unlimited water. Water restriction could lead to dehydration.

It is important to keep in mind that the age of the cat is a criterion to take into account. This is because cats’ kidneys work less well with old age, so they are more likely to develop chronic kidney disease. Food lines are now available to support the kidney function of senior cats and prevent their failure. Do not hesitate to discuss it with your veterinarian.

Certain breeds are also predisposed to develop certain kidney diseases, in particular polycystic disease or even amyloidosis which are among the possible causes of CRF.

In addition, a regular consultation for senior cats with your veterinarian is recommended every year or even every 6 months from the age of 7/8 years. Indeed, your veterinarian will be able to make a complete assessment in order in particular to check that the kidneys are functioning normally and to put a treatment in place in the event that the beginning of failure is detected.