What this means
A healthy cat's stool holds its shape, is moist but not smeared. Loose stool does not hold its shape and looks like porridge or water. Look in the litter box and notice the colour, the amount, any mucus, blood, visible bits of worm and how often your cat goes. If several cats share the home, try to work out which one has diarrhoea, because this matters to your vet.
There are very many causes, from a change of food and parasites to infections, inflammation of the gut and diseases of other organs, so you cannot tell them apart by looking. A vet may ask for a stool sample to test. If your cat goes outside the litter box, do not put it down to mischief: it may mean the cat cannot get there in time or cannot hold its stool, and that is worth mentioning.
Diarrhoea quickly dries the body out, especially in a kitten or an elderly cat. When a cat squats in the litter box, strains and passes little, it is not always diarrhoea: constipation and a blocked urinary tract can look the same, so do not wait in that case. Do not try to give or change anything at home instead of an examination, and show your vet a photo or a sample.
Possible causes
These are things that can cause this sign. It is not a diagnosis, and they are not equally likely for your cat.
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A change of food or unsuitable food
A sudden change of food or an unsuitable bite can irritate the gut. Diarrhoea then starts within hours or days.
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Parasites
Intestinal parasites can cause diarrhoea, sometimes with mucus or blood. Kittens are especially vulnerable.
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Infection
Viruses and bacteria can infect the gut. Besides loose stools a cat may vomit, run a fever and go off its food.
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Inflammation of the gut
Long-lasting inflammation of the gut wall causes diarrhoea that eases and returns, often with weight loss.
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Food allergy or intolerance
In some cats a part of the food sets off an immune reaction. Besides itching and skin changes, vomiting or diarrhoea can appear.
About the condition: Food and seasonal allergies -
Disease of other organs, and cancer
Some diseases outside the gut, and lymphoma of the gut, show as diarrhoea together with weight loss and a poorer appetite.
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Something swallowed that is toxic or unsuitable
Something toxic or an unsuitable object can cause sudden diarrhoea, often together with vomiting.
What else to watch for
These observations help your vet build the picture faster. Note down what you saw and when.
- When the diarrhoea began and how often your cat goes
- What the stool looks like: colour, mucus, blood, undigested food or worms
- Whether your cat is also vomiting
- Whether it eats and drinks as usual
- Whether it makes it to the litter box or goes elsewhere
- Whether it is losing weight or its energy has changed
When to book a routine visit
Book an examination if loose stools last more than a day, keep coming back, or your cat is eating less, losing weight or has become less lively, even if it otherwise looks bright. If your cat has not eaten for a day or more, contact a vet the same day.
Related conditions
Conditions whose entries mention this sign. The list is somewhere to read on, not a way to reach a diagnosis.
- Feline immunodeficiency virus (FIV) Infections A virus that slowly weakens a cat's immune system, so the body finds it harder and harder to fight off other infections. An infected cat can look perfectly healthy for a long time, even for years.
- Gastrointestinal conditions Digestion and liver A general name for upsets of the stomach and intestines: a cat vomits, has diarrhoea or constipation, or loses its appetite. Some pass quickly while others point to a more serious illness, so it matters how long they last.
- Intestinal worms Parasites Parasites that live in a cat's gut: roundworms, tapeworms and others. They take nutrients, irritate the gut and can slow a kitten's growth.
- Pancreatitis Digestion and liver Inflammation of the pancreas, a gland beside the stomach and gut. In cats it can show only as a few vague signs, such as listlessness and a lost appetite, so it is easy to miss.
- Feline panleukopenia (feline distemper) Infections A highly contagious viral disease that attacks the gut and the bone marrow, so the number of white blood cells in the blood suddenly drops. It is especially dangerous for kittens and can become life-threatening within a short time.
Body systems: Infections Digestion and liver Parasites