Kidney Failure in Cats
A diagnosis of kidney failure means that your cat’s kidneys are not working as
effectively as they should be. Although it is a progressive disease, with appropriate
care and commitment you can help your cat lead a happy life- often for many years.
Clinical signs of kidney failure are not seen until at least two thirds of the functional
kidney tissue has been lost. Unfortunately this makes diagnosing early stages of
kidney disease very difficult.
Kidney failure can be split into two groups: acute and chronic. Acute failure (usually
occurring over a period of days) can be caused by decreased blood supply to the
kidneys, e.g. dehydration, damage to the kidneys themselves, e.g. poisoning, or failure
to excrete urine, due to a blockage in the urethra or rupture of the bladder. Many cases
of acute failure are fully treatable, but if severe or left untreated, acute failure can
progress to chronic kidney failure.
Causes of kidney failure can be divided into two groups: congenital (present at birth)
and acquired. Congenital conditions include polycystic kidney disease. This is an
inherited condition, which is particularly common in Persian and related breeds.
Affected cats are born with small cysts within their kidneys. Over time these can get
larger and eventually put pressure on the surrounding kidney tissue. Kidney failure is
seen once about two thirds of the kidney tissue has been lost, typically at about 4
years of age. Most cases of kidney failure are acquired and are most often seen in
middle-aged and older cats.
Signs of Kidney Failure
Weight loss
Decreased appetite
Increased thirst
Increased urination
Lethargy
Vomiting
Mouth ulcers
Dehydration (despite drinking more)
Anaemia
How is Kidney Failure Diagnosed?
Diagnosis is made based on blood and urine samples. Cats with kidney failure have
higher levels of ‘waste products’ (urea and creatinine) in their blood, and are less able
to concentrate their urine compared to normal cats. It is important to check both blood
and urine as waste products in the blood can be raised for other reasons e.g.
dehydration, and urine can be dilute for many reasons other than kidney failure.
Sometimes kidney failure cats will have dehydration as well. In this case the
dehydration needs to be corrected before being able to tell how bad the kidney failure
is. Urine will also be checked for other things, including signs of infection and protein
loss in the urine.
What Other Tests May Need to be Done?
Many cats with kidney failure are anaemic. We would usually run a haematology
blood sample to check for anaemia and check for signs of infection. Cats with renal
failure can get anaemia for a number of reasons. These include low iron levels due to
decreased appetite, blood loss due to intestinal bleeding and decreased red blood cell
production (the kidney produces a chemical called erythropoietin, which stimulates
red blood cell production).
Kidney failure commonly leads to high phosphorous levels and low potassium levels.
Calcium and sodium levels can also sometimes be affected. If these levels weren’t
checked on the original blood sample then they may need to be checked once a
diagnosis of kidney disease has been made.
At least 20% of cats with kidney failure have high blood pressure. Left untreated this
can lead to blindness, heart failure and neurological problems, and can lead to a
quicker deterioration in kidney function. We can measure your cats blood pressure at
the surgery in a similar way to that which you have probably had done yourself at the
doctors. If your cat has high blood pressure, treatments can be given to bring this
down. Unfortunately stress can cause blood pressure to be high so occasionally we
may need to have a cat in for blood pressure measurement more than once before
making a decision on further treatment.
Some cats with kidney failure lose protein in their urine. This can contribute to weight
loss and is now thought to further contribute to further kidney damage. We can check
the amount of protein in your cat’s urine with a test called the Urine Protein
Creatinine ratio. If levels are high we can give your cat treatment to try to reduce this
protein loss.
Kidney biopsies from cats often show chronic damage irrespective of the original
cause, and this is one of the reasons that kidney biopsies are not commonly
recommended.
What Treatment may my Cat Need?
We will need to treat any reversibly or contributory factors of kidney disease where
these are present.
If your cat is dehydrated then he or she may need to come in for a drip. Usually
patients need to stay in for at least 24 hours and often require treatment for several
days. If dehydration is mild, we can sometimes encourage cats to drink more at home
by offering free access to water at all times (experiment with different shape bowls or
try a water fountain), by flavouring water (with unsalted water used to poach chicken
or fish, or with juice from a drained can of tuna/salmon in springwater NOT BRINE,
or by liquidising fish or prawns in water) or by moistening food.
One of the main things we can do to support kidney function is to switch to a
prescription kidney food. These contain high quality proteins, but at a reduced level
compared ordinary cat food. They also have reduced levels of phosphorous and
sodium, and higher levels of potassium and B vitamins. Cats fed a prescription kidney
food survive on average for 633 days, compared to 264 days for those that were not.
There are a number of different makes of kidney food available, so if your cat doesn’t
like one there are a few you can try.
Occasionally a cat will not eat the prescription food, or despite feeding prescription
food still has high blood phosphorous levels or low potassium. These cats may benefit
from phosphate binders to put on food and/or supplementary potassium.
If your cat is anaemic we may recommend supplement iron and give gastroprotectants
to reduce any bleeding into the stomach. We can try to stimulate red blood cell
production but this treatment is usually reserved for cats with severe anaemia as there
can be side effects.
If your cat has high blood pressure, drugs can be given to bring this down. Often two
drugs (ACE inhibitors and Amlodipine) are given simultaneously to have the
maximum effect.
If your cat has protein in his or her urine, drugs (angiotensin receptor blocker or ACE
inhibitors) can be used to reduce this loss.
How often will my cat need to be checked?
Once stabilised cats with kidney disease will need to be checked every 3 months.
Bloods and urinalysis are usually done at the same time. Cats on blood pressure
medications will require reassessment very 1-2 months until stable, then every 3
months. Cats with normal blood pressures should be rechecked every 6 months.
How much will treatment cost?
The cost of the first consultation is £27. Follow-up consultations are charged at
£22.99. Once your cat is stable, you will need to bring her or him in for a check every
3 months.
Blood sampling charges are £15.58 if done at the time of consult, £19.65 if you decide
to have a separate appointment to have the bloods taken. Lab fees to check kidney
values, phosphorous and potassium levels and haematology, including blood
sampling, cost about £75. This is normally advised every 3 months. The cost of £75 is
a reduced cost for owners who have bloods done at this recommended interval.
Prescription kidney food costs about 75p per pouch of meat and about £19 for a 2kg
bag of dried food. If your cat requires phosphate binders these cost about £12 to £15
per month depending on the product used. If your cat has low potassium levels and
requires supplementing, this costs between £22 and £44 per month depending on the
amount of extra potassium needed.
If your cat requires Fortekor, this costs about £23 for cats less than 5kg and about £45
per month for cats over 5kg.