kidney disease is very common in cats, with as much as 18% of the UK cat
population being effected. As any cat owner will have noticed, most cats
don’t drink nor pee much. This is because cats’ kidneys work
very hard through their lives concentrating their urine, much more than
dogs or people can, so it is not surprising that older cats are frequently
seen with kidney or ‘renal’ disease - however young cats can
occasionally develop problems as well.
There are several common underlying causes of kidney disease.
- In older cats Interstitial Nephritis is most frequently seen. This
is basically old age scarring, although there are many factors involved.
Diet and genetics don’t appear to play a role and there is nothing
that can be done to prevent the disease.
- Polycystic Kidney Disease (PKD)
is a very common problem in Persian cats - 20-30% of them can be affected.
Basically, kittens are born with cysts in their kidneys which gradually
enlarge, eventually destroying the normal surrounding renal tissue by
the time the cat is between 2 and 8 years old. Most Persian breeders
have their animals scanned when they are about a year old to detect
the problem before it is passed on to their offspring.
- Tumours are occasionally seen in middle-aged and older cats. These
are normally a type called lymphoma, and can respond well to chemotherapy
if caught early.
- Toxins such as antifreeze can very quickly damage the kidneys and
cause renal failure.
- Infection in the kidney (pyelonephritis) can occasionally occur, while
any chronic inflammation or infection in the body can cause a condition
called amyloidosis - complexes of antibodies form in the kidney tissue
and destroy the normal cells.
What to look for
As most people know the commonest signs seen with kidney failure are
increased drinking and urination. These tend to be quite marked although
may develop over many months and therefore go unnoticed. Cats will also
tend to have a reduced appetite and show weight loss.
As the condition progresses, regular vomiting of bile can occur and leg
weakness with disorientation may develop in extreme cases. Animals with
terminal kidney failure are very depressed, and eventually progress into
a coma and death.
Diagnosis of Kidney Disease
Diagnosis is normally best done by looking at a urine sample from the
cat and testing a blood sample. The blood sample will show an increase
in Urea, Creatinine and sometimes Phosphate levels. The cat may also be
a little anaemic. The urine is checked to see how concentrated it is by
measuring the specific gravity and also to look for any signs of infection
or protein loss. Repeat blood and urine samples should be taken 3-4 times
a year to monitor the condition.
Treatment depends on how ill the cat is when the diagnosis is made.
Very weak cats that are dehydrated and off their food, benefit from
the administration of fluids for a few days - either under the skin
or by the intravenous route i.e. dripping. Fluids flush kidney toxins
out of the cat’s system making them brighter and hopefully getting
their appetite back. If the cat doesn’t start eating well, it
will start going downhill again within a few days or weeks.
The mainstay of treatment is diet. A low protein, low phosphate diet
will reduce the workload for the kidney and so reduce the build up of
toxins in the cat’s bloodstream. There are several wet and dried
prescription diets available, so hopefully your cat will find something
he likes. Studies have shown that cats with kidney failure that eat
renal prescription diets will live 2-3 times longer than those that
don’t, so it is well worth trying to change them over. Unfortunately
trying to cook a low protein diet at home is often not successful -
cats tend to pick out only the meat which is obviously high in protein.
Fish and chicken is not good for cats with kidney disease either.
There are several medications that may be given to your cat in renal
failure. Fortekor is the most frequently used. This daily tablet reduces
the blood pressure in the kidneys, thereby slowing progression of the
disease and improving function. Most cats on this medication show an
improvement in appetite and gain weight. Antacids may be used to reduce
Antibiotics may be used if the blood or urine sample shows signs of
infection in the kidneys.
The outlook for a cat with kidney failure is very variable. A single
blood test and urine sample will tell us how bad the disease is but will
not tell us how fast it is progressing. Repeat samples after 2-4 weeks
will give us a better idea of how things are going and how well the cat
is responding to treatment. The severity of the disease when it is first
diagnosed, whether there are any concurrent infections and if the cat
will eat the special diets and medications, all contribute to the outcome.
It must be remembered however that the problem is not curable - treatment
will only slow or stabilise the progression for a while. However survival
times of anything between 6 months and 3 years can be achieved in most
cases. Renal transplants are not being carried out in this country at
present - rightly we feel. Please read our
article on this topic for more information.