As the kidneys gradually lose their ability to regulate
and remove waste products effectively, these waste products build up in
the blood. This is called uraemia and can make a cat feel very unwell.
In addition, CKD cats may have problems with excess stomach
acid. Gastrin is a gastro-intestinal hormone which stimulates the
secretion of gastric acid, which helps the stomach digest food. The
kidneys are responsible for the excretion of gastrin, but in CKD this
function may not work so well, resulting in the gastrin remaining in the
stomach and stimulating the production of too much gastric acid.
excess stomach acid can also make a cat feel very unwell. Generally speaking,
cats with creatinine over 265 (US: 3) will need help controlling stomach
Pet Place has some information about
gastric motility problems in cats (you don't need to register to read the
article, just click on the Close This Window link at the bottom of the
levels of urea seen in CKD cats are released into saliva. An enzyme in the bacteria in the
mouth called urease interacts with the urea and produces a very strong and distinctive odour. It is hard to
describe the aroma, though once smelled, never forgotten. It is sometimes
described as being an ammonia smell (like bleach) but it may smell more
like urine (ammonia is a constituent of urine), though neither description
really captures the smell. This smell will be particularly noticeable if
the cat crashes. If your
cat's breath smells more like nail polish remover, this may indicate
If the cat is very poorly or in a more advanced stage of renal
failure, the toxins produced by the body can cause ulceration of the gums,
which occurs when the uraemic waste is converted by the bacteria in the
mouth into ammonia (hence the smell of the cat's breath being described as
ammonia-like above). You may see ulcers in the cat's mouth if you look
inside, or in severe cases your cat may
vomit blood (which
may also be a sign of bleeding from further down the
You may also see drooling. Some cats paw at the mouth (which can also be a
sign of dental
Mouth ulcers are painful for the cat and often lead to
of appetite, or, even more distressingly, a desire to eat coupled with an
inability to do so - the cat may approach the food bowl and sniff the
food, then walk away. Mouth ulcers may also be a sign of
Check inside your cat's mouth regularly for inflamed gums or ulceration or
ask your vet to do so. I am sometimes asked what mouth ulcers look like.
They are usually a small area of white or yellow, sore-looking skin with a
thin red ring around it.
Long Beach Animal Hospital
has a photo
of mouth ulcers in a CKD cat. Starbrite Dental has a couple of photos
of human mouth ulcers.
uraemia is particularly bad, the cat may develop gastro-intestinal
bleeding. This is not easily detectable, but dark stools are one possible
sign, as is vomiting blood. Occasionally, however, dark stools are caused by iron
If gastro-intestinal bleeding remains untreated,
anaemia may result. If you
suspect gastro-intestinal bleeding, you should take a stool sample to your
vet for occult blood testing (when I did this for Ollie, I was the first
client who had ever requested this test; but it was positive). You can also buy the
EZ Detect test from pharmacies, which
tests for blood in the stool or urine (this is a human test but can also
be used for cats). CKD cats with this problem do not normally need to be
treated in hospital.
Pet Place has some information about
blood in stool (melena). You don't need to register to read the article,
just click on the Close This Window link at the bottom of the registration
may sometimes be seen in CKD cats secondary to the CKD. There are a number of other
different causes of diarrhoea, including
hyperthyroidism, inflammatory bowel disease (IBD), malabsorption problems, and parasites, so if the
diarrhoea lasts longer than a day or so, you must see your vet, both to
ensure your cat is OK (diarrhoea may cause or worsen
dehydration) and for a proper diagnosis.
causes of diarrhoea in a CKD cat include:
change of food, perhaps to a
prescription diet. It is better for a cat's
digestive system if a new food is introduced gradually - mix some of the
new food with the old and gradually increase the amount of the new food
in the mix over a period of several days.
intolerance. Because the goal is to reduce protein levels, some CKD
prescription foods in particular may have relatively high levels of
carbohydrates, and some cats who are used to a higher protein diet may
find these harder to process. Introducing the new food gradually may
help, but some cats are simply grain-intolerant.
antibiotics may develop diarrhoea.
Pet MD discusses this. If you think this might be the
cause, contact your vet and ask if you can switch to a different
antibiotic. Please do not just stop the antibiotic, however, or the
infection may return with a vengeance.
or MiraLAX, given to treat constipation, may
cause the opposite problem of diarrhoea. It is better to start lactulose
at a low level and increase as necessary.
sometimes people think
their cat has really runny diarrhoea, but in actual fact, the cat is
constipated and the runny liquid is all that can squeeze out round the
solid stool. This is known as "overflow incontinence".
So do be aware of this possibility, particularly if there is only a
small amount of liquid faeces.
cats have a distinctive aroma, which is caused by the levels of toxins in
the body. It is similar to the
bad breath aroma. You
may notice an increase in this aroma or it may develop for the first time
if your cat's bloodwork is worsening. In some cases, you may first notice
this smell when your cat
crashes. Thomas developed this smell seemingly
overnight when he crashed, but after treatment it gradually disappeared.
allergies are ruled out, this can be a uraemic itch, i.e. caused by the
levels of toxins in the blood.
Pruritus in certain internal diseases
(2007) Yonnova D Hippokratia11(2) pp67-71 mentions that
itching occurs in about 15% of uraemic human patients, so if your cat is scratching a lot or grooming
excessively, consider this possibility. Itching
is fairly common in cats with
high phosphorus levels, particularly if the high phosphorus levels go
untreated, resulting in
Alternatively itching may indicate a
B deficiency or be a sign of an
fatty acids deficiency. Occasionally itching can be a sign of liver
problems; if this is the case, your cat's bloodwork should show elevated liver
If your cat actually pulls out fur rather than
merely scratching, this may indicate
particularly on the face, may also be a side effect of the medication used
Pet MD mentions that twitching may be
caused by kidney disease.
Occasionally, if toxin levels are really high (and
particularly if a cat is in
Hours), a CKD cat may have seizures. In such cases, reducing
toxin levels is essential in order to avoid permanent damage to the brain;
but this may not be possible if the cat is in his/her final hours.
Seizures may take a number of different forms. There
may be the classic jerking and loss of consciousness, but being "spaced
out" or mentally absent or staring into space may also be a type of seizure.
has more information on what seizures may look like.