Colitis in dogs


  • Colitis is when the large intestine (colon) becomes inflamed.
  • Colitis causes diarrhoea that often contains blood and mucus.
  • Treatment for colitis depends how severely and how often your dog suffers from it.
  • Most dogs recover from colitis within a few days and have no further issues, but some need ongoing treatment for a form of colitis that comes and goes throughout life.
  • Contact your vet for an appointment if you suspect your dog has colitis - it can be helpful to take along a stool sample (or a photograph of your dog's stool).

Symptoms of colitis in dogs

  • Diarrhoea containing blood or mucus (or both)
  • Straining to poo
  • Vomiting
  • A painful abdomen (tummy) - your dog may stand with a hunched back or sit in a “prayer 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. It can be helpful to take a poo sample (or a photograph of your dog's poo) to show your vet.

How to collect a poo sample from your dog


Colitis can be caused by:

Some dogs have a form of colitis that comes and goes throughout life (chronic colitis). The causes of chronic colitis include:

  • Food allergies
  • Immune-mediated disease (your dog’s defenses 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). Click image to enlarge.


Treatment for colitis may include:

  • A bland diet (or special veterinary diet) for a short period.
  • De-worming treatment if your vet suspects worms could be the cause.
  • Probiotics (useful in some cases, but not all).
  • Anti-inflammatories specifically for the gut, which reduce inflammation and pain. Anti-inflammatories for the guts are very different to NSAIDs – which aren’t safe for colitis.

Contact you vet if your dog has been treated for colitis and hasn’t improved within a few days. They may need further investigations, which could include a food trial, blood tests, x-rays, a scan or biopsies (taking samples) of the colon.

If your dog suffers from colitis regularly (chronic colitis), you will need to work closely with your vet to prevent flare-ups. Prevention measures include:

  • Feeding a special food recommended by your vet
  • No treats (even dental chews!)
  • Prevent food scavenging
  • Regular worming treatments
  • Additional treatment from your vet during a flare-up.

Does my dog need antibiotics?

Antibiotics are rarely needed to treat colitis because bacteria aren’t usually involved.


Colitis is usually a one-off problem and following treatment, most dogs will recover within a few days.

Cases of chronic colitis can take quite a few weeks to improve but can be very well managed with ongoing treatment.


Treatment for colitis can become expensive, especially if it becomes a long-term problem. Consider insuring your dog as soon as you get them, before any signs of illness start. This will ensure you have all the support you need to care for them.

It’s also very important to speak openly to your vet about your finances, the cost of treatment, as well as what you think is right for your dog. There are often several treatment options so if one doesn’t work for you and your pet then your vet may be able to offer another.

Published: July 2019

Will you donate to help keep people and pets together?

Not everyone can afford to pay for treatment or advice for their poorly pets right now. That is why our Pet Health Hub is free for all pet owners to access.

As we receive no Government funding, we rely solely on donations from kind supporters like you.

Your support means we can keep providing this care. Please, support PDSA and donate to help keep people and pets together.

Written by vets and vet nurses. This advice is for UK pets only. Illustrations by Samantha Elmhurst.