The Common GI Parasite Pet Owners Should Know About


Does your dog like puddles? Streams? Dog parks? Then your dog has the potential to be exposed to the intestinal parasite Giardia. This sneaky parasite is common, but isn’t covered by regular “wormers”. Here’s a few bits about Giardia that dog owners should be aware of!

What is Giardia?

Giardia is a protozoal parasite that’s target location is the gastrointestinal tract in animals. While it can cause diarrhea like other intestinal parasites, it is a different class of parasite than roundworms, hookworms, and tapeworms. This means it has a different type of life cycle and is not treated by most regular wormers. 

How do dogs get Giardia?

Giardia is contracted via faecal-oral routes. This means infected faecal material from one animal makes its way into the mouth and then intestinal tract of another animal. In addition to dogs eating another dog’s poo and becoming directly infected, Giardia can also be contracted by drinking contaminated water sources like puddles/streams or even your dog stepping in contaminated soil and licking their feet clean!

Can people get Giardia?

Yes! People can also become infected with Giardia. Most Giardia is what we call species specific, meaning certain strains of the parasite tend to stick to infecting certain species (dogs, cats, humans, etc). Because of this, direct infection from dogs to people can occur but is extremely uncommon. More often, humans and dogs become infected at the same time when both drinking from the same contaminated water source (i.e. drinking from a stream while hiking). 

How do I know if my dog has Giardia?

Your vet can test a fresh faecal sample from your dog to see if it is positive for Giardia parasites!

What clinical signs does Giardia cause?

Giardia causes GI signs, particularly watery diarrhoea. This diarrhoea is often discoloured and has a very foul odour. Dogs with Giardia may also experience changes in appetite or vomiting. Some dogs can also carry Giardia without showing any clinical signs!

How is Giardia treated?

Unlike many other common intestinal parasites, Giardia is not targeted by our typical preventative worming medications. Because Giardia is in a completely different class of parasite, it requires a different type of drug to eliminate it. Products containing the drug fenbendazole are typically used, and may require more than one round of treatment to clear the parasite. These can be prescribed by your vet in the instance of a positive faecal test. 

Diarrhea should never be ignored in our pets, because there are so many underlying causes including parasites! Recurrent changes in your pets stool consistency should always be addressed with your vet. If you are worried about the potential for your dog to have Giardia, contact your vet for an appointment!

Dr. Kirsten Ronngren, DVM MRCVS

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