Cats are particularly prone to kidney damage and it has a variety of causes. Infections, cancers, exposure to toxins, and malfunction of the immune system may all be responsible for starting a slow process of damage, leading eventually to loss of function and kidney failure. The original cause is often no longer present at the time of diagnosis and sometimes will never be discovered.
The body has more kidney tissue than it needs, so much may be lost before symptoms develop – and before blood tests show changes. This slow progressive process is referred to as “chronic” kidney disease. Occasionally, previously healthy kidneys suffer sudden and massive damage (acute kidney disease) but this is less common.
What do the kidneys do?
Kidneys filter the blood and take out poisonous by-products produced by the workings of the body. These are added to water to form urine.
They also get rid of excess water into urine or, when water is lacking, can concentrate urine to reduce water loss. When they are diseased, the ability to concentrate urine is lost and the animal has to drink more to get rid of the body’s waste products.
The kidney regulates the number of various salts (sodium and potassium, among others) within the body by moving smaller or larger amounts into the urine. Kidney disease may cause some of these to build up within the circulation making the animal ill and perpetuating the kidney damage.
Other functions of the kidney include the production of chemicals called hormones. One hormone causes the blood vessels to expand or contract – lowering or increasing the blood pressure. Another hormone stimulates the body to make red blood cells so, when the kidney’s hormone production is out of balance, this can sometimes cause anemia.
How is kidney disease diagnosed?
Diagnosis is reached by a combination of blood and urine tests. An increase in the toxic substances that the kidney normally removes can be measured in the bloodstream. Looking at the concentration of the urine is also helpful.
In kidney disease, urine is diluted and more prone to infection – which can be detected by tests. In some cases, the only way of finding the cause of the disease is by biopsy (removing a piece of kidney for examination).
This involves an operation, therefore, it is often not done unless there is a chance that a definitive diagnosis could help in the treatment of your cat. In many cases, the damage – which causes the symptoms – cannot be reversed.
What are the symptoms?
Everyone knows that in an animal, drinking lots of water can be a sign of kidney disease, but this can also be a symptom of other illnesses.
Cats are discreet and maybe secret drinkers, so early signs of excess thirst may be missed and they may become quite ill before treatment is sought.
As kidney disease advances, other symptoms include weight loss, signs of dehydration, poor appetite, smelly breath, a sore mouth, vomiting and weakness. Eventually, there may be twitchiness or even fits. However, these symptoms are common to many illnesses, not just kidney disease.
What is the treatment?
There is no cure. Treatment aims to minimize the symptoms, by reducing toxin production, keeping salt levels normal, and slowing the rate of ongoing damage.
Cats that are unwell and severely dehydrated may benefit from intravenous fluids to re-hydrate and flush out toxins. If improvement does not follow, then kidney damage may be severe, and you should consider the options carefully with your vet. Home nursing is very important.
The toxins produce nausea, loss of appetite, and sometimes mouth and stomach ulcers. Tempting food, such as fresh fish or chicken, warmed and given by hand may help. If loss of appetite is long-term, your cat’s quality of life becomes questionable and should be discussed with your vet.
How long will my cat live?
This varies, depending on the severity of the disease, the underlying cause, and the speed at which ongoing kidney damage is occurring – something which only time will reveal.
The most important consideration is the well-being and happiness of the patient. Some cats, although thin and drinking lots, stay reasonably well for one to two years or more. Others can be unwell and deteriorate rapidly within weeks.
Long-term treatment
Free access to water is essential, especially in the summer. If the cat is accidentally shut in without water, dehydration and toxin build-up can happen rapidly.
Encourage your cat to drink by placing water bowls in several rooms. Cats prefer dog size bowls, which should be filled to the brim and placed away from feeding places.
Some cats prefer running water so consider getting a water fountain. Many of the toxins come from dietary protein, and there is increasing evidence that low protein diets improve general condition and longevity. Cats can be very reluctant to try new foods, so try to start dietary change at initial diagnosis, when the cat’s appetite may be better. Be prepared to mix new and old diets together for one to two weeks.
Warming food may help. However, with a cat that absolutely refuses to eat the diet, maintaining a healthy appetite becomes more important than eating a special diet.
You need to discuss what is best for your animal with your vet. Anabolic steroids may be given in an attempt to improve appetite and reduce weight loss.
Other drugs, which are sometimes used, include ACE inhibitors. They may preserve function in undamaged parts of the kidney, while anti-nausea drugs, appetite stimulants, and anti-ulcer drugs may improve appetite.
Excessive potassium loss due to failing kidneys may lead to weakness, therefore potassium powder or tablets may be prescribed.
Phosphates may build up in the circulation of patients with kidney problems, worsening the kidney damage, so your vet may prescribe medicine to reduce your cat’s intake of phosphates, especially if your cat is not eating a special low protein diet.
A blood pressure check may be suggested. High blood pressure worsens kidney damage and unfortunately, kidney disease can cause high blood pressure – working in a vicious circle. In advanced cases of anemia, there are treatments to stimulate red blood cell production, but these are expensive, only work short-term, and are not suitable in all cases.
Your vet will discuss with you what is best for your cat. In summary, kidney disease cannot be cured, but there are treatments that may make your pet feel better.
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