Diarrhoea is one of the most common reasons for a veterinary visit. Most cases are mild and settle within a few days — but diarrhoea can also be a sign of serious illness. Here is what causes it, how to care for your pet at home and when to contact the clinic.
Most Common Causes
In dogs, the most common cause is eating something unsuitable, such as rubbish or table scraps, or changing food too quickly. In cats, a sudden change of diet is a common trigger. Other causes include intestinal parasites (such as Giardia, roundworms and coccidia), stress, food allergy or intolerance, toxins and swallowed foreign objects. Bacterial and viral infections are also possible — the most serious being parvovirus in unvaccinated puppies and panleukopenia (feline parvovirus) in unvaccinated kittens. Diarrhoea that lasts longer than about three weeks or keeps coming back is called chronic and always needs investigating.
Home Care
If your adult pet is otherwise bright, eating and drinking normally, and the diarrhoea is not bloody, you can try home care for 24–48 hours. Do not starve your pet: fasting is no longer recommended — even dogs with severe intestinal infection recovered faster when fed early. Cats especially must keep eating: after just a few days of eating little or nothing, a cat — particularly an overweight one — can develop dangerous fatty liver (hepatic lipidosis). Offer a bland, low-fat, easily digestible diet in small portions 4–6 times a day. The clinic sells Royal Canin Gastro Intestinal diets for dogs and cats; for a few days, boiled skinless, boneless chicken with boiled rice (about one part chicken to two parts rice) also works, but it is not a complete long-term diet. Always provide fresh water. Once the stool is normal, continue the bland diet for a few days, then return gradually to the usual food over about a week. Wash your hands after cleaning up: some causes, such as Campylobacter and Salmonella bacteria, can spread to people. Supervise children’s handwashing.
Probiotics and Medicines
A veterinary probiotic may help — for cats, the clinic sells FortiFlora — although the evidence is modest. Never give human medicines without veterinary advice. Loperamide (Imodium) can cause serious neurological poisoning in dogs carrying the MDR1 gene mutation — common in Collies, Australian Shepherds and Shelties, and also found in other breeds and crosses. Products containing bismuth subsalicylate (such as Pepto-Bismol, sold abroad) can poison cats. In dogs, international guidelines advise against antibiotics for acute diarrhoea — even when it contains blood — unless the dog is severely ill.
When to Contact the Veterinarian
Contact the clinic the same day if: the diarrhoea contains blood (bright red, or black and tarry); your pet vomits repeatedly or cannot keep water down; your pet is lethargic or weak, or its belly seems painful; you see signs of dehydration (dry, tacky gums, sunken eyes, or skin that is slow to fall back when gently lifted); your pet may have eaten something poisonous or a foreign object; or your cat has not eaten for more than a day. A male cat straining in the litter box may have a urinary blockage — an emergency. Puppies and kittens — especially unvaccinated ones — need prompt assessment: they dehydrate quickly, and parvovirus can be life-threatening. Elderly pets, small breeds and chronically ill animals also dehydrate faster. If there is no improvement after 48 hours of home care, or the diarrhoea recurs, book an examination. Tip: a photo of the stool helps the veterinarian.
Prevention
Change food gradually over 7–10 days. Avoid table scraps, bones and access to rubbish. Deworm according to your pet’s risk — a faecal sample helps show whether treatment is needed. Pharmacies sell dewormers without a prescription, but they do not treat every cause of diarrhoea — Giardia and coccidia, for example, need a diagnosis and a specific treatment. Keep vaccinations up to date. Reduce stress during changes; pheromone products (such as Feliway for cats) may help some animals, though the evidence is limited.
Contact Us
If you are unsure, call us on (06) 321 7300 or email info@saarivet.fi — you can attach photos. We will advise whether a visit is needed.
Sources
- Jessen LR, Werner M, Singleton D, et al. European Network for Optimization of Veterinary Antimicrobial Therapy (ENOVAT) guidelines for antimicrobial use in canine acute diarrhoea. The Veterinary Journal 2024;307:106208. doi.org
- Mohr AJ, Leisewitz AL, Jacobson LS, et al. Effect of early enteral nutrition on intestinal permeability, intestinal protein loss, and outcome in dogs with severe parvoviral enteritis. Journal of Veterinary Internal Medicine 2003;17(6):791–798. doi.org
- Bybee SN, Scorza AV, Lappin MR. Effect of the probiotic Enterococcus faecium SF68 on presence of diarrhea in cats and dogs housed in an animal shelter. Journal of Veterinary Internal Medicine 2011;25(4):856–860. doi.org
- Merck Veterinary Manual: Feline Hepatic Lipidosis. merckvetmanual.com
- International Cat Care: Inappetence in cats. icatcare.org
- Washington State University, WADDL: MDR1 in dogs. waddl.vetmed.wsu.edu
- Merck Veterinary Manual: Drugs Used to Treat Diarrhea in Monogastric Animals. merckvetmanual.com
- CDC Healthy Pets: Dogs. cdc.gov
- Frank D, Beauchamp G, Palestrini C. Systematic review of the use of pheromones for treatment of undesirable behavior in cats and dogs. JAVMA 2010;236(12):1308–1316. doi.org