Information Letter - Kidney Disease of Pets

What is kidney insufficiency?

Kidney insufficiency or renal failure is a reduced kidney function in a pet.

The kidneys play a very important role in the body:

  • They regulate the fluid balance in the body, i.e. they indicate how much a pet should urinate and thus drink. 
  • In this way, they also regulate the blood pressure of a pet.
  • They filter the blood, removing waste products from the blood and excreting them in the urine. This keeps important substances in the blood in the right quantity.
  • They have a large reserve capacity, so that the tasks can still be carried out well if part of the kidneys is damaged. However, when more than 70% of the kidneys are damaged, they cannot function properly anymore and symptoms of kidney failure may occur.

There are several causes for kidney insufficiency, the most important of which is old age and consequently wear and tear. It can also be caused by infections (inflammation of the renal pelvis), poisoning, tumours, drugs, crystal formation and/or stone formation, and congenital abnormalities, among others.

What are the symptoms of kidney failure?

  • Drinking and urinating a lot
    The kidneys can no longer concentrate the urine well, so a cat will urinate more and therefore drink more. The urine will be more watery and therefore the specific gravity of the urine (the concentration) will decrease.


  • Nausea, vomiting, less appetite
    In case of renal insufficiency, the kidneys cannot remove important waste products from the blood properly, such as urea and creatinine. Because of the increased waste, a pet can get nausea and ulcers can develop on the tongue (reduced appetite and pain when eating), stomach (nausea and vomiting) or intestines (diarrhea symptoms) causing a pet to lose weight.


  • Anemia
    The kidneys normally produce erythropoietin (EPO), a hormone that stimulates the production of red blood cells. In case of renal insufficiency, the production of this hormone may be insufficient, resulting in reduced production of red blood cells (anaemia). If a pet develops anaemia he/she may have pale mucous membranes, less energy and become lethargic.


  • Dull coat, general poor condition
    A pet with renal insufficiency has a reduced ability to retain moisture. Because of this and because of waste products, the coat will lose moisture and look duller. Frequently, animals with renal insufficiency are less willing to wash and groom themselves.

How do we diagnose?

The diagnosis of kidney failure is made on the basis of symptoms, blood tests and urine tests.

  • Blood test
    • In the blood, the waste products urea and creatinine are determined. 
    • Also, the SDMA is determined; this is a parameter that is released when damage occurs at a specific location in the kidney. 
    • Also the percentage of red blood cells (haematocrit) and the blood salts phosphate and potassium are measured. The phosphate in the blood can become elevated because the kidneys cannot eliminate the excess phosphate properly. The potassium level in the blood can become too low, which in turn affects the muscles in the body.


  • Urine test
    • The urine tests to see if the kidneys are able to concentrate the urine properly. Renal insufficiency can only be said to exist when the kidneys can no longer concentrate properly. 
    • We can also check whether the filtering function of the kidneys is still intact by looking at whether there are more proteins than normal in the urine (the UPC ratio).

By means of the above tests, we can determine whether there is a case of renal insufficiency, but not yet what the cause is. This requires further investigation. These include a puncture of the kidneys, urine culture, ultrasound examination, X-rays and/or blood pressure measurement. If an underlying cause is found, such as inflammation of the renal pelvis, it will be treated. 

What is chronic renal insufficiency and how does it progress?

Sometimes, there is residual damage to the kidneys and unfortunately the kidneys will no longer recover 100%, we speak of chronic renal insufficiency. Even if no underlying cause for the kidney insufficiency is found, we call this chronic kidney insufficiency. 

When part of the kidneys is not functioning properly anymore, the healthy part will try to take over the tasks, so the healthy cells will work extra hard. Because of this increased workload, the healthy cells will eventually also break down due to exhaustion. So, the kidney failure will slowly get worse, this is called a progressive course of the disease. The increased phosphate in the blood can also precipitate into the kidneys, causing the kidney to break down even faster.

Unfortunately, it is not possible to cure chronic renal insufficiency. A pet will therefore be a kidney patient for the rest of his/her life. Then we try to support the kidneys the best we can for the rest of their lives with a diet and if necessary medication.

How do we treat chronic renal insufficiency?

The treatment of chronic renal insufficiency is aimed at improving both the life expectancy and the quality of life of the animal. Depending on the stage of the disease and possible complications, the best treatment for the animal will be decided.

  • Extra fluids
    If chronic renal failure is diagnosed, we may need to help the pet get rid of excess waste. For this purpose, he/she is admitted and we prefer to give an intravenous infusion (fluids directly into the blood vessel).

    In addition to the intravenous infusion, we can also give fluids under the skin, which also flushes out the kidneys. This application of fluids under the skin (called a subcutaneous infusion) can also be done at home.

    We also advise to stimulate the animal as much as possible to take in fluids on its own and to keep the kidneys flushed by feeding it canned food, letting it drink from the tap, buying a drinking fountain, etc.


  • Renal diet
    The production of waste products is reduced by eating a renal diet. This diet contains less protein and phosphate, so less creatinine, urea and phosphate will be formed in the blood. The kidneys then have to excrete less waste products and less phosphate will be deposited in the kidneys.

    Unfortunately pets often find kidney diet food less tasty than other food, because it contains less salt. However, the most important thing is that an animal eats enough instead of what it eats (like the kidney diet)! The kidney diet is therefore only started when there is a good appetite.


  • Treatment too high phosphate level
    If the phosphate level in the blood becomes too high despite the kidney diet or because the kidney diet is not eaten (well), it is also an option to give Ipakitine©. Ipakitine© is a phosphate binder and with this we can at least limit the absorption of phosphate.


  • Treatment of low potassium
    When the potassium level in the blood is too low, the food supplement Tumil-K© (a powder) can be sprinkled over the feed. Tumil-K contains potassium in a tasty protein base.


  • Vitamin B
    Kidney patients have an increased need for vitamin B because they lose a lot of it through the urine. B vitamins are added to a kidney diet, but sometimes there may be reasons to administer more B vitamins, usually in the form of an injection.


  • Treatment of protein loss via the kidneys
    Semintra© helps to prevent protein loss via the kidneys. If a pet loses too much protein through the urine, we can limit this and slow down the progression of renal insufficiency.


  • Treatment of hypertension
    In chronic renal insufficiency, more than half of the pets develop elevated blood pressure, or hypertension. This will cause the kidneys to deteriorate faster, but other organs such as the brain and eyes will also suffer. By measuring the blood pressure and if necessary giving medication against hypertension (Amodip©) we can protect the kidneys and other organs.


  • Symptomatic therapy
    If a pet has nausea and/or vomiting, we can support him/her as best we can by giving Cerenia© against the nausea and vomiting. In case of a lack of food, we can give Mirataz© to stimulate the appetite. 

What are the follow-up appointments?

It is wise to have an animal with chronic renal insufficiency checked regularly by us.

The first check-up is recommended two months after the diagnosis. If the kidney values are stable, it is recommended to visit at least twice a year

Animals with advanced chronic renal insufficiency are recommended to be checked four or more times a year. The doctor will discuss with you what is applicable. 

During these check-ups, the pet will be fully examined again, body weight will be monitored, blood and urine will be taken for examination and blood pressure will be measured. If necessary, medication and/or food supplements will be prescribed and/or administered.

Stay alert and signal in time!

A pet cannot talk and therefore it is important to be alert. You can watch for changes in behavior, appetite, drinking and urinating, but also for changes in weight and activity level. In case of doubt or questions, please contact the clinic immediately.

If you have any further questions regarding this information letter, please do not hesitate to contact us.

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