Giardia Symptoms in Dogs

What Does Giardia Poop Look Like?

Giardia poop is usually:

• Soft to pudding-like rather than fully watery^1,5
• Pale and greasy or fatty-looking^1,2
• Coated with or containing mucus^3,5
• Unusually foul-smelling^3,2

Blood is usually absent.¹ Many other conditions cause similar stool, so a stool test is the only way to know. Compare other stool types on our dog poop chart and see mucus in dog poop.

How Dogs Act When They Have Giardia

Most dogs with Giardia act normally, eat well and stay playful, even with loose stools.^4,1 Signs of illness are more likely in puppies, stressed dogs, dogs living in kennels or shelters and dogs with other illnesses. They may have a poor appetite, vomiting, tiredness, weight loss or a dull coat and poor growth.^5,1,3 In rare cases, severe or long-lasting infection in a young animal can be life-threatening.¹

How Soon Dogs Start Shedding Giardia

Dogs start passing cysts in their stool about 3 to 16 days after swallowing them, depending on the source.^1,5 Shedding can continue for weeks to months and is often on and off, especially in long-lasting infections.^5,1 This is why a single negative test doesn't rule Giardia out.^3,4

Giardia in Puppies

Puppies under about 6 months are the most likely to have symptoms.^2,6 Infection rates are high in young dogs: 41% of park dogs under a year old in one European study, and 16% to 44% of dogs in breeding-kennel studies.^9,11 Puppies from shelters and from large breeders are infected more often.^12,11 Puppies often carry several gut parasites or viruses at once, so vets may test for more than one cause of diarrhea.^8,11 See causes of puppy diarrhea.

How Vets Test for Giardia

• Zinc sulfate centrifugal flotation: the stool is spun in a special solution and checked under a microscope for cysts. Other solutions can distort the cysts.^4,13
• Fecal antigen test: a quick in-clinic or lab test that detects Giardia proteins. It's more sensitive than a float but can stay positive after the infection is gone.^4,9,14
• Direct smear: a drop of very fresh stool examined for live, moving Giardia.⁴
• PCR: a lab test that's very sensitive and can tell which type of Giardia a dog carries, which matters if someone at home has a weak immune system.^4,13,10

For a dog with signs, CAPC recommends combining a float with an antigen test or PCR. Because cysts are shed on and off, several samples over a few days may be needed.^4,1 Routine Giardia screening of healthy dogs isn't usually recommended, except in kennels, breeding facilities and some homes with recurring problems or vulnerable people.^13,14

Conditions That Can Look Like Giardia

• Coccidia, another single-celled parasite common in puppies. See coccidia in dogs.^15,12
• Worms, such as roundworms, hookworms and whipworms. See worms in dogs.^12,16
• Viruses in puppies, especially parvovirus and coronavirus.⁸
• Eating something unusual or a sudden diet change. See dog diarrhea.

Frequently Asked Questions

What color is Giardia poop?

It's often paler than normal, with a greasy look and mucus. Color alone can't tell you it's Giardia.

Can a dog have Giardia without diarrhea?

Yes. Most infected dogs have no symptoms but can still pass cysts.

Can Giardia clear up on its own?

Many dogs never get sick, and guidelines usually don't treat healthy dogs. A dog with diarrhea should be tested and treated.

Why did my dog test negative but still have Giardia?

Cysts are shed on and off, so a single sample can miss them. Your vet may test several samples or use a more sensitive test.

Can I touch my dog if he has Giardia?

Yes. Just wash your hands afterward and keep his coat clean.