Giardia In Dogs: Signs, Symptoms and Treatment of This Summer Parasite

As a vet, I see lots of diarrhoea – and when I say “lots” I mean lots. One of the common causes of diarrhoea in dogs worldwide is Giardia, a parasite that dogs get from drinking from puddles, lakes, streams or other sources of stagnant water. While it’s a year-round risk, Giardia cases peak in the summer because people and pets spend more time outdoors and travelling. Here’s everything you need to know about Giardia in dogs, including how to spot it, treat it and prevent it from happening in the first place.

What is Giardia?

Giardia is a ubiquitous single-celled protozoan parasite that can live in the intestines of dogs. The parasite thrives in cool, moist environments and can survive for months in the right conditions. Giardia can infect dogs, cats, wild animals and people too.

How do dogs get Giardia?

Giardiasis is transmitted by a faecal-oral route, meaning that the parasite is swallowed in food and water contaminated with faeces. Your pet does not have to eat poo to get the parasite. In fact, dogs most commonly get Giardia by drinking from contaminated water sources (think: puddles, gutters, lakes and streams).

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What are the symptoms of Giardia in dogs?

Giardia symptoms in dogs can include diarrhoea, gas, abdominal discomfort, nausea and vomiting. That said, an infection can be present without symptoms. Not all dogs show symptoms of a Giardia infection but when they do the most common symptom is watery diarrhoea. Additional Giardia symptoms in dogs may include:

• severe diarrhoea (often with blood and mucus)

• weight loss

• decreased appetite

• vomiting

• gas

• dehydration

• dry or poor coat appearance

If your dog has diarrhoea that persists beyond 24 hours or is very sudden and severe, take them to the vet asap.

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How is Giardia in dogs diagnosed?

Diagnosis is often made by evaluating faecal material under a microscope. However, the little parasite Giardia can be difficult to find. So, in addition, we use a ‘snap test’, adding some stool to a solution that gives us a positive or negative result for Giardia (like a pregnancy test for poo). This test is very sensitive to the presence of Giardia in dogs.

What is the treatment for Giardia in dogs?

To treat Giardia in dogs, veterinarians will typically prescribe a combination of giardiasis medication such as fenbendazole (dewormer) and metronidazole (antibiotic) for about 10 days. In small puppies or dogs sensitive to this antibiotic, a dewormer known as Panacur can be used instead for 5–10 days. Your pet’s poo should be retested two to four weeks after finishing the medication.

You may have heard about a Giardia vaccine. Research shows it can prevent Giardia infections in both dogs and humans. However, it is not licensed in the UK.

How long does it take for a dog to recover from Giardia?

Most healthy dogs recover from Giardia within a few weeks. In some cases, supportive treatment, including IV fluids and hospitalisation, may be required if dehydration or severe diarrhoea persists. Puppies, senior dogs and those with compromised immune systems are at higher risk for complications, including death. Your veterinarian will determine the best course of treatment.

How can Giardia in dogs be prevented?

The best way to prevent a Giardia infection is to keep your dog from drinking out of puddles, lakes, streams or other sources of stagnant water (easier said than done, but effort is everything). Remember, Giardia is transmitted orally and what better place to have concentrated levels of poo than a park, especially when some pet parents are not diligent about removing their dog’s poo.

It may also be advisable to treat other animals in the same household while treating the infected, symptomatic pet.

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There are also environmental control measures that can be taken to prevent reinfection. Be vigilant about clearing faecal material from the environment. If your dog has been diagnosed with Giardia, it is often recommended that you wash as many areas of your environment as possible, followed by disinfection with a solution of bleach diluted in water (another measure that’s easier said than done).

• Pick up your dog’s poo frequently.

• If you have cats (indoors or outdoors), pick up their poo, too.

• Clean your dog’s bowls regularly with soap and water.

• Wash your dog’s toys and bedding often.

• Disinfect areas such as crates and kennels.

• Avoid walking your dog in moist areas where other dogs or wildlife may have pooed.

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Frequently asked questions

Can Giardia infections recur?

Yes, dogs can easily reinfect themselves with Giardia. That’s why it’s important to thoroughly clean all the areas your dog may have touched.

Is Giardia more common in puppies?

Because their immune systems aren't as developed as older dogs, puppies are more likely to contract Giardia.

Is there a vaccine available to prevent Giardia in puppies?

Yes, but it is not available in the UK and is usually reserved for high-risk dogs in other countries.

Can I get Giardia from my dog?

It’s possible but unlikely. There are several kinds of Giardia and dogs are most commonly infected with a variant that doesn’t infect humans.

References

• Cryptosporidiosis and giardiasis in dogs and cats: Veterinary and public health importance

• Giardia in Dogs

• Guard Against Giardia in Dogs

• Giardia for Pet Owners

• Enteropathogen infections in canine puppies: (Co-)occurrence, clinical relevance and risk factors

• Giardia: Infection, treatment and prevention