Colitis in dogs


Colitis is inflammation (swelling) of the colon. The colon is also called the large intestine, it’s the last part of the guts before the anus (bottom).

Colitis causes diarrhoea that often contains blood and mucus.

Most cases of colitis are a ‘one-off’ but some dogs are prone to the condition and develop an ongoing form of colitis that comes and goes throughout life.

Symptoms of colitis in dogs

  • Diarrhoea containing blood or mucus (or both)
  • Straining to poo
  • Vomiting
  • A painful abdomen (tummy) - your dog may have a hunched back or sit in a “praying position”.
Photograph of a dog's poo containing blood and mucus

Blood and mucus in a dog's stool

When to contact your vet

Contact your vet if your dog has any of the symptoms listed above or you are worried they may have colitis.

You know your dog best. If they don’t have the symptoms listed above but you are still concerned it’s always best to contact your vet.


One-off colitis:

One off colitis often only lasts a few days and is usually caused by:

  • Stress
  • Eating something unusual (which causes gut irritation)
  • An infection in the guts, usually worms, other parasites or occasionally bacteria.

Ongoing colitis:

Ongoing colitis comes and goes throughout a dog's life and is usually caused by:

  • Food allergies
  • Immune-mediated (your dog’s body attacking its own colon)
  • An ongoing gut infection, usually bacteria or parasites.
Illustration to show location of colon in dogs

The colon is the last part of the guts before the anus (bottom)


One-off colitis usually gets better within a few days with minimal treatment. However, if your vet is concerned they may give your dog treatment to make them feel more comfortable and speed up their recovery. This treatment may include:

  • Anti-inflammatories for the gut - anti-inflammatories (specifically for the guts) help reduce pain and inflammation. These are very different to NSAIDs which are not safe to be used in cases of colitis.
  • De-worming treatment may be prescribed if your vet suspects worms could be the cause.
  • A bland diet or special veterinary diet for a short period.
  • Probiotics can be useful for some dogs suffering with colitis.
  • Antibiotics are rarely needed because colitis is not often caused by bacteria. However, they may be prescribed if your vet thinks they will be helpful.

Ongoing colitis often comes and goes throughout a dog's life. For this reason, treatment also tends to be for life.

  • Special food. If your dog suffers with colitis regularly and no underlying cause is found, it’s likely your vet will prescribe a special veterinary diet with high levels of fibre.

It can take quite a few weeks to see improvements but management is usually very successfully with help from your vet.


Following treatment, most dogs recover from colitis quickly. If your dog isn’t getting better and is suffering from ongoing colitis, contact your vet – your dog may need further investigation. Investigations may include a food trial, blood tests, x-rays or biopsies (taking samples) of the colon. These samples can be sent away to a laboratory for examination to try and find out the cause of the problem.

Even if a cause isn’t found, colitis can usually be managed successfully with help from your vet.


If your dog suffers from ongoing colitis you will need to work closely with your vet to prevent flare-ups.

This may include:

  • Feeding specialist food recommended by your vet
  • No treats (even dental chews!)
  • No food scavenging
  • Regular worming treatments
  • Vet visits for additional treatment during flare-ups.
Published: June 2018

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Illustrations by Samantha Elmhurst