Kidney failure

Your cat is diagnosed with kidney failure. We can imagine that this news may come as a shock, but luckily there are lots of things we can do to give your cat a good life, despite the disease. This letter gives you some information about chronic kidney failure, so the treatment and the evolution of the disease become clearer to you.

How does the kidney work

Cats have 2 kidneys. The most important function of the kidneys is to filter the blood, so waste products are removed from the body. These waste products eventually are the urine that we urinate. The kidneys do this with uncountable little filters, the nephrons. Kidneys have a big reserve capacity.

Kidney schematic
Kidney schematic

What is chronic kidney failure

Only if 2/3 of the kidneys don’t function anymore, you’ll see clinical symptoms and we speak of kidney failure. But usually, the decline of the kidney function is going on for months, or even years. Generally we see kidney failure in older cats, and the course is often unknown. The symptoms you might see are lethargy, eating less, drink/ urinate more, weight loss, unhealthy fur.

In case of these complaints, the vet will conduct an investigation in the form of urine and blood tests, a blood pressure measurement and an ultrasound.


We examine the urine for specific gravity. This says something about the wateriness of the urine. In renal failure, the kidneys cannot concentrate the urine and the urine will become very watery. That is why kidney patients (have to) drink a lot. We also investigate whether bacteria are present that can damage the kidney and we check whether there is protein loss.

Blood test

In principle, we determine at least 6 parameters in the blood: urea, creatinine, SDMA, potassium, phosphate and hematocrit.

  • Urea: Measures the amount of waste products in the blood. When this level is high, the cat doesn’t feel well, is vomiting and lethargic.
  • Creatinine: Is a measure for the damage of the kidney.
  • SDMA is a determination that can detect renal failure at an early stage. Creatinine only rises when 75% of the kidney tissue is damaged. SDMA already rises when 40% of the kidneys are damaged. Cats usually feel fine at that point and incipient renal failure is easily missed.
  • Potassium: Is an electrolyte that often is too low in patients with serious kidney damage. This must be corrected.
  • Phosphate: Kidney failure causes an increased phosphate level. A high level of phosphate is damaging for the kidneys and other organs.
  • Hematocrit: Kidneys produce a specific hormone; erythropoietin (epo). This hormone ensures that new red blood cells are made in the bone merrow. Kidney failure can cause anemia.


Through imaging we get to know more about the cause of kidney failure.

Blood Pressure Measurement

Most kidney patients have high blood pressure and to prevent further damage this will have to be corrected.

What kind of treatments are there

Depending on the results of the tests, we will take the necessary steps to provide the right treatment.

IV infusion

If the urea level is high, we will flush the kidneys for 3 days (dialysis). Often, after this, the urea level shows a significant drop, and the patient feels a lot better. This infusion is given directly into the bloodstream. Also, the creatinine level can drop after this treatment. Sometimes we must repeat the infusion subcutaneously.

Potassium correction

Potassium takes care of a lot of processes in the body. If the potassium level in the blood is too low, this can cause high heart rate, lethargy and ventroflexion of the neck. Trough the infusion, we can correct the potassium level.

Adapted diet

Special kidney diet supports the kidneys and helps to slow down the process of deterioration. It contributes to the improvement of life quality. Research shows that cats that eat kidney diet, live 2 years longer than cats who don’t. Kidney diet is a complete food with a special protein source, a raised level of potassium and a reduced level of phosphate. Because of this there will be less burden on the kidneys. It’s best to give this food lifelong.


Certain medications support the kidneys. Semintra® regulates the protein and potassium excretion and the blood pressure of the kidneys, so that the filter function is maintained for longer. When the blood pressure is greatly increased, there are blood pressure lowering agents such as Amodip®. Renalzin®/Ipakitine® are phosphate binders. Kidney failure causes elevated phosphate. Increased phosphate, in turn, is harmful to the kidneys and other organs. A kidney diet is already reduced in phosphate, but if your cat does not like this, a phosphate binder over the normal diet is also an option. We can also temporarily prescribe an appetite stimulant Mirataz® if your cat is not eating enough. This is a transdermal ointment that you apply to the inside of the auricle.

Provide enough water

Kidney patients can’t concentrate their urine very well, so they have to drink more than cats without kidney problems. Some cats are very picky where and what kind of water they want to drink. Make sure there’s always enough water, in different spots, for more information visit Drinking behavior of cats. If your cat didn’t drink for a day, always visit the vet for an infusion!

Clean teeth and healthy gums

It is known that bacteria of infected gums, can cause damage to the kidney’s trough the bloodstream. In some cases, it can be helpful to do a dental treatment.

What is the prognosis

Unfortunately the kidneys of your cat won’t get better anymore. But we can help to give your cat a good life with the disease. If the urea level is too high, the prognosis depends on the level after the dialysis. If the creatinine level is too high, it’s difficult to say what the prognosis will be. What we do know, is that with the right treatment, we can slow down the process of deterioration of the kidney function, so your cat can have a good quality of life for years!

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