Giardia in dogs


  • Giardia is a small parasite that causes diarrhoea by attacking the lining of the guts.
  • Giardia spreads in poo – dogs catch it when they are exposed to infected poo particles (in water, food or the environment).
  • It often takes more than one course of treatment to cure giardia.
  • Humans and other animals can catch giardia.

Giardia explained

Giardia is a tiny parasite that causes diarrhoea by attacking the lining of the guts. It causes very watery, pungent smelling diarrhoea that often contains blood.

When to contact your vet

Contact your vet if you are concerned your dog may have giardia or they have any of the symptoms above. It’s a good idea to call your vet for advice if your dog has been in contact with another dog who’s recently been diagnosed with giardia.

Diarrhoea left for too long can lead to dehydration. Book an appointment with your vet immediately if your dog has any of the following symptoms:

  • Diarrhoea for more than 2-3 days
  • Intermittent diarrhoea for 2 weeks or more
  • Young puppy or an elderly dog with diarrhoea
  • Diarrhoea and other health issues
  • Diarrhoea whilst taking medication.

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.

How did my dog catch Giardia?

Giardia spreads in poo, your dog could have caught it anywhere they’ve encountered infected poo particles, e.g.

  • contaminated water
  • contaminated food
  • contact with an infected dog
  • in the environment.

Giardia can hang around for months. Even once an infected poo has been cleared away, giardia bugs can continue living where they were dropped.

Humans can catch giardia so it’s important to wash your hands after cleaning up dog poo or meeting a dog with diarrhoea.

Giardia in the environment

Giardia spreads in poo and can stay around for months after the poo has been cleared

Treatment for Giardia in dogs

Your vet may ask for a poo sample to help diagnose your dog, so it may be helpful to collect one before the appointment. Watch our video below on how to collect a poo sample from your dog.

Your vet may prescribe:

Many dogs need more than one course of treatment.

If your dog has developed severe diarrhoea and become unwell, they may need admitting into the veterinary hospital for more intensive treatment (e.g. a drip to give fluids directly into their blood stream, injectable medications and careful feeding).


Your dog's diarrhoea should improve a couple of weeks after treatment; however, some dog's need more than one course of treatment to cure the problem.

Once your dog has recovered from giardia, it’s uncommon for ongoing problems to develop. Speak to your vet if you have any concerns.

Published July 2018

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Written by vets and vet nurses

Illustrations by Samantha Elmhurst