Chronic Kidney Failure in Cats

Unfortunately kidney failure is fairly common in older cats. Over time the small filtering units of the kidney, called nephrons, begin to fail. Initially only a small percentage will fail, which leads to the remaining nephrons working harder to compensate. In turn the overworked nephrons begin to fail also and it is an ongoing irreversible cycle.

In most cases the external signs that we see due to kidney failure don’t show until at least 75% of the nephrons have failed. This means that if we wait to diagnose cats when they are showing signs of kidney disease, often their kidneys will only have 25% or less of normal function remaining. This highlights the importance of annual health checks which include blood tests for mature cats, even though they might be physically doing well on the outside. By looking at changes within the blood we can pick up early kidney disease and manage it appropriately to give your cat the best outcome.

Previously we would diagnose kidney disease by assessing the urine, and also the level of two kidney markers in the blood – urea and creatinine. For the last few years we have been able to use a new marker called SDMA to assess kidney function in conjunction with our original markers. SDMA increases in the blood much earlier in the kidney disease process than our original kidney markers, allowing us to pick up disease very early. Until a few months ago we would have to send blood to the lab to test for SDMA, but now we are able to perform this test with our in-house blood analyser, giving us much quicker results.

Symptoms
As stated above, signs of kidney failure only really start to show once a larger proportion of kidney function is lost. The main signs that we see are an increase in a cat’s thirst and drinking habits, which often correlates with an increased need to urinate (though with most cats urinating outside this is harder to pick up on). Other common signs include weight loss (due to a reduced appetite), poor coat quality, lethargy, vomiting, blindness, and ulceration in the mouth.

Treatment
The earlier we pick up that there is kidney disease present, the earlier we can start to manage and treat it to slow the progression to keep the cat healthy and happy for longer. Unfortunately we can’t reverse or alter what has already happened, but we can treat to minimise the progression of the disease.

Main treatment of renal disease consists of:

• Prescription renal diets; these diets have been specifically formulated to be lower in certain components which damage the kidneys such as protein, phosphate, and sodium. Studies have shown that cats with renal disease that are fed on these diets show a slower rate of disease progression and in turn have a better long term prognosis.
• Medication to lower blood pressure as high blood pressure can be a common side effect of kidney disease and in turn can cause damage to the kidneys and other sensitive structures in the body.
• Medication to prevent protein loss through the kidneys into the urine if this is occurring.
• It is also important to ensure cats with kidney disease always have access to lots of fresh water as it is important for their kidneys to stay well hydrated.

In conclusion, if your cat is older than 8-10 years then we strongly recommend regular blood tests even if they appear healthy. It is so important to allow us to detect disease earlier so that your cat can have a better life for longer.