My cat has diarrhoea: causes, what to do and when to worry
Almost every cat has an episode of soft stools at some point that clears up on its own. But diarrhoea in a young kitten, diarrhoea that lasts for weeks or diarrhoea with blood and lethargy are not the same thing, and some home remedies can make it much worse.
What counts as diarrhoea
Normal cat faeces are formed, can be scooped up whole and leave no mark. We talk about diarrhoea when they are soft, pasty or liquid, when there are more bowel movements than usual or when they appear outside the litter tray because the cat does not make it in time. It is also worth noting the type: if they are large in volume and not very frequent, the problem is usually in the small intestine; if there are many small ones, with mucus or fresh red blood and the cat strains, it is usually the large intestine. Sometimes what looks like constipation, a cat that spends a long time straining in the tray, is actually colitis. And in males, straining with nothing coming out can be a urinary blockage, which is an emergency.
The most common causes in young cats
In kittens and young cats, the first suspects are parasites: intestinal worms, coccidia, Giardia and Tritrichomonas foetus, the last one typical of kittens from catteries or multi-cat homes and responsible for diarrhoea that comes and goes for months. Then come sudden diet changes, the stress of adoption or a journey, and milk: most adult cats do not digest lactose well, and the saucer of milk is a classic cause of diarrhoea. In unvaccinated kittens, feline panleukopenia, a virus similar to canine parvovirus, starts with vomiting and diarrhoea and is very serious.
Causes in adult and older cats
In an adult cat, acute diarrhoea lasting a day or two is usually due to something they ate, a change of food or a passing infection. When it lasts more than two or three weeks it is considered chronic, and the causes change: food-responsive chronic enteropathy, inflammatory bowel disease (IBD), intestinal lymphoma (common in older cats), hyperthyroidism, pancreatic problems, or food allergy or intolerance. In an older cat that has diarrhoea, eats ravenously and still loses weight, hyperthyroidism is one of the first things to rule out with a simple blood test.
When it is an emergency
See the vet the same day if it is a kitten under six months that is also flat, not eating or vomiting, especially if not fully vaccinated; if there is a lot of blood or black, tarry faeces; if the diarrhoea is very watery and frequent; if they are also vomiting, not eating or listless; if they have a fever or, the opposite, feel cold; if the gums are pale or dry and tacky, or if you know they may have eaten something toxic. Kittens dehydrate within hours. And remember the feline rule: a cat that stops eating for more than a day also needs to see the vet, with or without diarrhoea.
What to do at home if they are bright
If it is an adult that is bright, eating and drinking and only has soft stools, you can wait a day or two while keeping an eye on them. Do not withhold food for long: fasting does not suit cats. Offer small, frequent portions of their usual food or a veterinary gastrointestinal diet, which is a much better option than improvising. Make sure they drink: fresh water in several places and wet food help. Veterinary probiotics made specifically for cats can be useful in mild diarrhoea. Keep the litter tray clean and wash your hands well, because some parasites spread to other cats and to people. If there is no improvement within 48 hours, it gets worse or any warning sign appears, go to the vet.
Chicken and rice, with caveats
The homemade bland diet of boiled chicken and rice, so popular for dogs, is not the best option for cats: they are obligate carnivores, rice gives them little and many will not eat it. If you need to improvise for a few hours, boiled skinless chicken or turkey is better, with no salt, no spices and no onion or garlic, in small pieces. But for more than a day, the right choice is a veterinary feline gastrointestinal diet, which is balanced and highly digestible. What you should not give is milk, cold cuts, ham, carton stock (it usually contains onion) or fatty leftovers.
What you must never give them
Do not use human anti-diarrhoeal medicines. Some contain salicylates, from the same family as aspirin, which are toxic to cats; others, such as those that slow the gut, can make an infection worse and cause neurological effects. Paracetamol, which someone might give if the cat seems sore, is deadly to cats even in the tiniest amounts. Do not give leftover antibiotics from another animal or a person either: most cases of diarrhoea do not need them, and indiscriminate use encourages resistance. And do not give activated charcoal or clays unless your vet tells you to.
The stool sample: three days is better
Many parasites are not shed in every stool, so a single sample can come back negative even if the cat has them. The vet will usually ask for a faecal analysis with samples collected on two or three different days, in a clean pot and kept in the fridge, not the freezer. There are specific tests for Giardia and Tritrichomonas, including PCR. Take them in fresh to the appointment: they will save you time and tests. Worming "just in case" without testing sometimes works, but if the diarrhoea comes back it is worth knowing which parasite is involved, because not all of them respond to the same treatment.
What the vet will do and what it costs
For mild acute diarrhoea: an examination, a hydration check and supportive treatment, meaning diet, a probiotic and, if needed, a parasite treatment or fluids. In kittens with severe signs, a panleukopenia test and possibly hospitalisation. For chronic diarrhoea it goes step by step: faecal tests, a switch to an elimination or hydrolysed diet for a few weeks, blood tests including thyroid hormone, vitamin B12 and pancreatic tests, abdominal ultrasound and, if there is no response, biopsies. As a guide in Spain: consultation 40 to 60 €, faecal analysis 25 to 50 €, diarrhoea PCR panel 80 to 150 €, blood tests 80 to 160 € and ultrasound 70 to 150 €.
Preventing what can be prevented
Parasite control based on your cat's real risk, more often in kittens and in cats that hunt. Full kitten vaccination against panleukopenia, which is one of the core vaccines. Gradual food changes over seven to ten days, mixing in more of the new food each time. No milk and no leftovers. A clean litter tray, especially in multi-cat homes, to break reinfection cycles. And if you adopt a kitten, have the vet check them in the first week with a faecal test, because many arrive with parasites even after being wormed.
Mild diarrhoea in a bright adult can be monitored for a day or two with small meals and water. In kittens, with blood, with vomiting, with lethargy or if it lasts more than two or three weeks, go to the vet with a stool sample from several days. And no milk or human anti-diarrhoeal medicines.
Educational content from Michipedia, translated from the Spanish original. It does not replace the advice of a vet or a feline behaviour specialist. Every cat is an individual.