Chronic Kidney Failure in Cats

“I have brought my cat to see you because he is drinking a lot and using his litter tray a lot more than he used to. I think he may have lost some weight too.”

This is one of the most common sentences we hear from our cat owners during consultations here at the surgery. Increased thirst is a very common symptom in many of the conditions we see in our feline patients (see earlier blog posts on diabetes and hyperthyroidism), but one particular condition that we always need to consider as a possible diagnosis at such times is chronic kidney (renal) failure.

What is chronic renal failure?

The kidneys play many important roles in the normal functioning of the healthy body, including filtering toxins from the blood stream and regulating the amount of water, salt and electrolytes in the body, as well as helping to maintain red blood cell numbers and normal blood pressure. Chronic renal failure can be described as a progressively reduced ability of the kidneys to perform these vital functions through irreversible damage to and degeneration of the kidney tissue. Sadly, in the vast majority of cases the cause of this damage is not known, but it does appear more commonly later in life, hence why most of our feline patients with chronic renal failure are middle-aged or older. There are some well recognised specific causes of chronic renal failure in cats (including for example, chronic urinary tract infections), and if such conditions are identified during investigations, treatment can be directed against them to help halt the progression of the chronic renal failure.

What are the main signs of chronic renal failure?

The main signs of chronic renal failure in cats usually develop slowly and insidiously as more and more of the kidney tissue is affected and the kidneys are less able to perform their functions adequately. The signs all relate to this reduction in the ability of the kidneys to function normally and are:

– Increased thirst
– Increased frequency of passing urine
– Weight loss
– Reduced appetite
– Bad breath (halitosis)
– Vomiting and diarrhoea
– Poor coat and dehydration
– Weakness and lethargy

As our knowledge of people who donate their kidneys and live happily with only one kidney tells us, kidneys can perform their functions well even if much of their tissue is not healthy and working as it should. In fact, the signs of chronic renal failure in cats usually do not develop until at least 70% of the kidneys tissue is irreversibly damaged. This fact explains why early diagnosis and treatment is vital to maximise the chances of slowing down the progression of the disease.

How is chronic renal failure diagnosed?

As with all conditions, taking a good history is a vital part of reaching a diagnosis. If you are concerned that your cat is showing signs that may be consistent with chronic renal disease, the best advice would be to make an appointment here at the surgery as soon as you can. The vet will ask you questions about any changes you may have noticed in your cat’s behaviour, appetite and thirst, and after examining your cat thoroughly will most likely want to perform some investigations.
Tests performed on blood and urine samples usually give us most of the information we need to diagnose chronic renal failure, therefore if you can bring a fresh urine sample from your cat along with you to the appointment this can be very helpful. Collecting a urine sample from a cat is not always the easiest thing in the world to do, but we do have some tricks up our sleeves to help, so do ask our staff here at the surgery for advice. If not possible at home, we can collect a urine sample here at the surgery at the same time as taking a blood sample. Tests performed on these samples help us determine how well the kidneys are performing their functions, and can in some cases also help us find an underlying specific cause for chronic renal failure.
Other investigations may be performed at this time, including checking blood pressure and screening for other conditions that can be seen together with chronic renal failure such as hyperthyroidism (see previous blog post). An ultrasound scan of the kidneys can also be very useful in ruling out a primary, specific cause of the chronic renal failure.

My cat has chronic renal failure. Can the condition be cured?

Chronic renal failure results from irreversible damage of the kidney tissue, therefore the most frustrating thing about this condition is that it is not possible to restore the ability of affected kidney tissue to function normally. However, all is not lost, since with early diagnosis, there is much that can be done to successfully manage the condition, slow down it’s progression, and help our feline patients to lead happy, good quality lives. As with many of these chronic conditions, early diagnosis holds the key to success. If a primary, specific cause has been identified by investigations, your vet will start treatment for this cause (for example, antibiotic treatment for a bacterial urinary tract infection) in addition to managing the chronic renal disease. Since the vast majority of cases do not have a recognised specific primary cause, most feline renal patients will be started on treatment aimed at managing the condition and reducing the rate of progression:

– Feeding a diet of reduced protein and phosphate is a vital part of slowing down the progression of chronic renal failure and also reducing the occurrence and severity of the signs of renal failure. There are now some very good complete diets specifically designed for cats with renal failure, and your vet is likely to suggest trying one of these. Some cats find reduced protein diets less palatable, and therefore our staff at the surgery can discuss alternatives with you. Sometimes it is necessary to add palatable phosphate binders to the diet, if blood samples show high phosphate levels even if feeding a reduced phosphate diet.
– Increasing water intake is important, since cats with chronic renal failure commonly become dehydrated. Feeding a wet food can help with this, but cats are notoriously fussy when it comes to diet, therefore those that refuse wet food can be encouraged to drink more with the use of water fountains or extra water bowls at home. Our staff here at the surgery can give you more advice on ways to increase water intake.
– It may be necessary to give intravenous fluids to some cats that regularly become dehydrated. This usually involves a short stay at the surgery in our specially designed cat ward. Here we can safely administer fluids intravenously to restore fluid levels, in a peaceful environment where cats feel relaxed and stress levels are reduced. Some cats will need extra treatment if they are showing other signs, for example reduced appetite and vomiting.
– ACE-inhibitors are drugs that have been used for a long time to help manage human kidney disease, and they can similarly help manage the condition in cats. They come in tablet form and work by increasing blood flow through the kidney and can slow down the progression of kidney disease. They are particularly effective in those cats which are passing excessive amounts of protein through their kidneys, and hence regularly urine tests are important to assess the suitability of ACE-Inhibitors as a treatment option.
– High blood pressure (hypertension) is commonly seen in cats with chronic renal failure, and therefore regular checking of blood pressure is vital to prevent high blood pressure causing further damage. ACE-inhibitors can have a positive effect on controlling blood pressure, but some cases will need extra treatments to allow blood pressure to be kept within the normal range.
– Supplements of potassium are sometimes necessary, since low blood potassium levels are often seen in feline renal patients and can lead to reduced appetite and weakness.
– The use of anabolic steroids and vitamins by regular injection can help combat the anaemia seen in many cats with chronic renal failure. Your vet may choose to administer such treatments at regular check-ups here at the surgery. These check-ups are an extremely vital part of the management of chronic feline renal failure, allowing monitoring of the progression of the condition and the adjustment of treatment as necessary.

Can my cat lead a normal life with chronic renal failure?

Even though chronic renal failure cannot be cured, the measures described above can be very effective at controlling chronic renal failure in cats, slowing down it’s progression, and minimising the clinical signs seen with the condition. Every case is unique, and our staff here at the surgery are skilled at using the right combination of treatments to ensure, if diagnosed with chronic renal failure, your cat can live as long and happy a life as possible. If you have any concerns or need more advice, don’t hesitate to contact us here at the surgery, or make an appointment with one of our vets or nurses.’