Digestive health in dogs and cats
Most digestive upsets in a bright, well pet are short-lived. What matters is the pattern and your pet's overall state — and knowing the signs that mean 'see a vet'. Use the guides below for specific symptoms, and the sections here for the basics of diet, stool and hydration.
- Pick the symptom you're seeing — each guide covers causes, home care and red flags.
- Sudden diet changes are a common, avoidable trigger; switch foods gradually.
- Watch stool, appetite and hydration — these tell you a lot.
- Blood, black tarry stool, repeated vomiting, a painful or bloated belly, or a flat, weak pet mean urgent care.
Digestive symptom guides
Choose what you're seeing:
Vomiting
Bringing up food or bile — causes and red flags.
Diarrhoea
Loose or watery stool; when to watch, when to worry.
Not eating
Appetite loss — more urgent in cats.
Constipation
Straining to pass stool — guide in progress.
Gas & bloating
Wind and a swollen belly — guide in progress.
Straining to urinate
Not digestive, but often confused with it — can be an emergency.
What 'digestion' means
Digestion is how your pet breaks food down and absorbs nutrients, from mouth to stomach to intestines. Upsets show up as vomiting, diarrhoea, appetite changes, gas, or changes in stool. A single episode in an otherwise well pet is often minor; recurring or severe signs, or signs in a very young, old or unwell pet, deserve veterinary attention.
Food and food transitions
A sudden switch of diet is one of the most common causes of tummy upset. When changing foods, do it gradually over about 5–7 days, mixing increasing amounts of the new food into the old. Keep rich, fatty or spiced human food, and scavenged street food, off the menu. If your pet has a sensitive stomach, talk to your vet before experimenting — this page can't diagnose a food allergy or intolerance from symptoms alone.
Stool and hydration
Your pet's stool is a useful health signal: note consistency, colour, frequency and any blood or mucus, and bring a fresh sample to vet visits. Hydration matters too — fresh water should always be available, and dehydration (tacky gums, skin that stays tented) is the real danger in vomiting or diarrhoea. In cats especially, encouraging water intake with wet food or fountains supports gut and kidney health.
Parasites and the gut
Intestinal worms and protozoa (like Giardia) are common causes of digestive signs, particularly in young animals. Routine, vet-guided deworming and good faecal hygiene help — see our deworming guide. Fleas can transmit a tapeworm, another reason parasite control ties into gut health.
When digestive symptoms are urgent
Most upsets are mild, but these signs mean prompt veterinary care.
- Blood in vomit or stool, or black, tarry stool
- Repeated vomiting, or unable to keep water down
- A bloated, hard or painful belly (can be an emergency)
- A flat, weak or collapsed pet, or signs of dehydration
- Any cat that is also not eating, or a very young, old or unwell pet
Frequently asked questions
My pet vomited once but seems fine — should I worry?
A single vomit in a bright, active pet that then eats, drinks and behaves normally is often nothing serious. Watch them, offer water, and see our vomiting guide. Repeated vomiting, blood, or a dull pet needs a vet.
How do I switch my pet's food without upsetting their stomach?
Transition gradually over 5–7 days, mixing more of the new food into the old each day. A sudden change is a common cause of diarrhoea.
What should I look for in my pet's stool?
Note consistency, colour, frequency, and any blood or mucus. Black, tarry stool or fresh blood is worth a prompt call. A fresh sample helps your vet run useful tests.
Could worms be causing my pet's digestive signs?
Yes — worms and protozoa are common, especially in young animals. Routine deworming and faecal testing with your vet help. See our deworming guide.
Sources
- SourceMerck Veterinary Manual — Colitis in Small Animals. merckvetmanual.com
- SourceCompanion Animal Parasite Council (CAPC) — General Guidelines for Dogs and Cats. capcvet.org
- SourceVCA Animal Hospitals — Flea Control in Cats (tapeworm and fleas). vcahospitals.com