What is it? CKD, also known as Chronic Renal Failure or Kidney failure, is a progressive loss of kidney function - sadly, it is very common in cats. A cat's kidneys play a vital role in filtering waste products and toxins out of their blood; they also control the production of red blood cells (to carry oxygen) and help to regulate blood pressure.
What causes it? The kidneys have a reserve capacity (the "functional reserve") of about 60%. Throughout life, some of the nephrons (the actual filtering tubes) will be damaged or lost, due to disease, injury or (most commonly) old age and overwork. Eventually, so many have been damaged that the kidney's function is impaired - we call this Chronic Kidney Disease, to distinguish it from Acute disease where an injury, shock or poisoning has destroyed or damaged large amounts of the kidney tissue in a single event.
What cats are at risk? All cats - in fact, most cats over the age of 12 probably have some degree of kidney disease.
What are the symptoms? Typically, symptoms of CKD develop gradually and insidiously. The usual signs are weight loss, increased thirst and increased urination. As waste products and toxins build up in the bloodstream, a strong metallic smell and ulceration of the mouth may develop, followed by dehydration, seizures, collapse and then death. Other possible effects of kidney failure include anaemia (pale gums and difficulty catching their breath) and high blood pressure, which can cause blindness or strokes. Many affected cats also have unusually low blood potassium levels, causing muscle weakness - typically, a drooping head carriage.
How is it diagnosed? The most common way to diagnose kidney failure is with a blood test - increased amounts of wastes such as urea and creatinine can easily be detected, as can low red blood cell counts in anaemia. Urine tests are also useful, as the cat's diseased kidneys cannot concentrate their urine as much as in a healthy cat, plus they also tend to leak protein. Tests of blood pressure are also very important to determine whether eye and brain damage are likely.
How can it be treated or managed? There is no cure for CKD in cats (kidney transplants are technically possible, but are banned in the UK). However, the disease can usually be managed with appropriate diet, free access to water and medication. A cat with kidney failure requires a diet with the minimum QUANTITY of high QUALITY protein, low phosphate levels and high potassium levels. This is usually best provided with a specific renal diet, but if a cat will not eat it, a phosphate binding agent and supplementary potassium can be added to their normal diet. Free access to water will help to combat dehydration, and medications such as ACE inhibitors will reduce protein loss through the kidneys and help to stabilise blood pressure. If the cat's blood pressure is dangerously high, other drugs such as amlodipine may be needed to reduce it to a safe range.
Can it be prevented? No, there is no way to prevent CKD. A good quality diet, and avoidance of toxins such as antifreeze may delay the onset, but it is probably inevitable if the cat lives long enough.