Cat Diseases & Illnesses – Chronic Kidney Failure
Chronic renal failure (CRF) is a common disease in older cats and occurs when the kidneys become damaged over a period of time. Often the underlying cause is unknown but it can occur as a result of infections, inflammation or tumours amongst other things. The kidneys can compensate well initially and symptoms of chronic renal failure are not usually seen until approximately 75% of the renal tissue is damaged. The kidneys cannot regenerate like organs such as the liver and so this damage is irreversible and usually progressive but there are many ways to manage the disease and slow progression, giving affected cats a good quality of life.
The normal role of the kidneys is to filter waste products from the blood which are then eliminated via the urine. They are also important in the regulation of electrolytes such as sodium and potassium, the control of water balance in the body and the production of some hormones such as erythropoietin which stimulates red blood cell production. As the kidneys begin to fail, waste products build up in the blood and electrolyte and water balance is disrupted causing the cat to become unwell.
Symptoms of Chronic Kidney Failure in Cats
Cats with chronic renal failure usually present with a range of non specific symptoms such as weight loss, reduced appetite, poor coat quality, vomiting and an increased thirst or polydipsia. In more advanced cases, cats become dehydrated and can appear collapsed and have ulcers on their gums. If you see any of these signs in your cat then you should have them examined by your vet. Clinical examination alone will not give a definitive diagnosis but the vet may be able to detect dehydration or possibly misshapen or irregular kidneys.
Diagnosis of Chronic Kidney Failure in Cats
Diagnosis requires a blood sample to be taken which in cases of chronic renal failure will show azotaemia, an accumulation of waste products called urea and creatinine in the blood. Blood tests may also show anaemia, a lower than normal number of red blood cells. A urine sample is also very useful as this may show up signs of infection or inflammation and also how well the kidneys are able to concentrate the urine, a function that is lost in chronic renal failure. In some cases, further tests such as monitoring blood pressure (often high in chronic renal failure) or imaging of the kidneys may be indicated to try and find an underlying cause of the renal failure.
Management of Chronic Kidney Failure in Cats
If your cat first presents to the vet with severe renal failure and is dehydrated then the vet may advise admitting your cat to the hospital and putting them on a drip. If however your cat presents to the vet in the earlier stages of the disease then management at home is possible.
Diet is the mainstay of managing chronic renal failure and some pet food companies make prescription diets especially formulated for cats with kidney disease. Examples of these are Hill’s g/d and k/d and Royal Canin Walthams Renal diet. These are available in wet or dry formulations and can really help kidney function in cats with chronic renal failure. Diets such as k/d and Renal diet have restricted protein levels as it is the protein breakdown products, urea and creatinine, that accumulate in the blood and cause the cats to be nauseous, vomit and go off their food. Renal diet and k/d also contain lower levels of phosphate, which is retained by damaged kidneys and Sodium, which can contribute to raising the blood pressure, further damaging the kidneys. Conversely, k/d and Renal diet contain higher levels of substances like Vitamin B and potassium which can be lost in the urine of cats with chronic renal failure and enough calories so that affected cats can maintain their body weight, despite not having a good appetite. Water intake is also very important because cats with chronic renal failure become dehydrated easily as their kidneys cannot concentrate the urine to retain water. A clean, fresh water source is vital. Feeding wet food can be another good way of increasing the cat’s moisture intake. If diet alone is not sufficient to manage your cat’s renal failure then additional medication may be needed.
Phosphate binders: damaged kidneys will retain phosphate which contributes to the animal feeling unwell. Phosphate binders reduce the amount of phosphate that is available to be absorbed from the gut, therefore reducing blood levels of phosphate. Common phosphate binders include Ipakitine, a powder that is added to the food and Renalzin, a paste that is also added to the food daily.
Angiotensin Converting Enzyme Inhibitors (ACEI): These are a group of drugs that are useful in chronic renal failure. They reduce the amount of protein that is being lost in the urine and also help to reduce the blood pressure which, as mentioned, is often high in these cats. The most common ACEI is a drug called benazepril which comes as tablets called Fortekor or Benazecare. These come as palatable flavoured tablets in various sizes, the dose of which will be decided by your vet.
Many other medications may be of use such as further agents to reduce blood pressure, medications to prevent or treat anaemia and to help reduce nausea and vomiting. These would be decided upon by the vet on a case by case basis depending on the particular symptoms that your cat is displaying.