How Do Dogs Get Giardia and Can It Spread to Your Family?

If your dog has been having bouts of loose, greasy stool and your vet mentioned giardia, you’re probably doing a lot of late-night searching right now. Here’s the short version: giardia is a common intestinal parasite, it’s treatable, and most healthy dogs recover fully. This article walks you through everything you need to know, from what giardia actually is to how long it takes to clear and whether you need to worry about catching it yourself.

Let’s start at the beginning.

What is giardia in dogs?

Giardia (canine giardiasis) is an infection caused by a tiny, single-celled parasite called Giardia duodenalis. It lives in the small intestine and disrupts how your dog absorbs nutrients and water, which is why diarrhea is the main symptom. It’s not a worm and it’s not a bacteria. It’s in its own category of microscopic parasites called protozoa.

The parasite exists in two forms. The active form (trophozoite) attaches to the intestinal wall and causes damage. The dormant form (cyst) gets shed in your dog’s stool and can survive in the environment for weeks, especially in cool, damp conditions. When another dog (or person) swallows those cysts, the cycle starts over.

Symptoms of giardia in dogs

Not every dog with giardia looks sick. Some carry the parasite without showing any signs at all, particularly adult dogs with strong immune systems. But when symptoms do appear, here’s what you’re likely to notice:

• Soft, watery, or greasy diarrhea that may be pale or yellowish
• Stool with a particularly foul smell, sometimes with a slimy or mucus-like coating
• Increased gas and bloating
• Vomiting (less common, but it happens)
• Weight loss or failure to gain weight, especially in puppies
• Low energy or seeming generally off

Puppies, older dogs, and dogs with weakened immune systems tend to get hit harder. If your dog is very young or already dealing with another health issue, giardia symptoms can escalate more quickly and warrant a faster vet visit.

What does giardia poop look like in dogs?

Giardia stool is usually soft to liquid, pale in color, and greasy-looking, almost like it has a sheen to it. It often smells worse than a typical upset stomach would. You might also see mucus in the stool. It’s not always bloody, but it can be. If you’re seeing any of this consistently over more than a day or two, it’s worth calling your vet and bringing a fresh stool sample with you.

What causes giardia in dogs, and how does it spread?

Dogs get giardia by swallowing the cysts, the dormant, infectious form of the parasite. This usually happens through:

• Drinking from contaminated water sources like puddles, ponds, streams, or standing water
• Sniffing or licking contaminated soil or surfaces
• Direct contact with infected feces from another dog
• Grooming themselves after walking through a contaminated area

Dog parks, kennels, shelters, and anywhere dogs share a water bowl or outdoor space are higher-risk environments. That’s not a reason to avoid them, just a reason to stay on top of hygiene and watch for symptoms after your dog’s been around other animals.

How is giardia diagnosed?

Your vet will diagnose giardia using a fecal test, which means they’ll examine a stool sample under a microscope to look for cysts or other signs of the parasite. Because giardia cysts aren’t shed in every single bowel movement, one negative test doesn’t always rule it out. Your vet may ask for multiple samples collected over a few days, or run an additional test called a fecal antigen test, where the lab looks for specific proteins from the parasite rather than the cysts themselves. It’s more sensitive and tends to catch infections that a standard fecal float might miss.

Don’t wait to bring a sample in if symptoms persist. The sooner you get a confirmed diagnosis, the sooner treatment can start.

Giardia in dogs: treatment and recovery

Giardia doesn’t typically go away on its own, at least not reliably or quickly. Most dogs need medication to clear the infection, and your vet will prescribe one or both of the following:

• Fenbendazole: an antiparasitic medication given over several days, often the first choice for giardia in dogs
• Metronidazole: an antibiotic and antiprotozoal (a drug that targets parasites like giardia) that’s sometimes used alone or combined with fenbendazole for more stubborn cases

Both medications are generally well-tolerated. Your vet will guide you on dosing and duration based on your dog’s size and how severe the infection is.

How long does giardia last in dogs?

With treatment, most dogs start to improve within a few days and fully clear the infection within one to three weeks. Your vet will likely recommend a follow-up fecal test after treatment to confirm the parasite is gone. Some dogs need a second round of medication, especially if reinfection is a concern in multi-pet households or if the environment wasn’t thoroughly cleaned.

Cleaning your home during treatment

Treating your dog is only half the job. Giardia cysts can linger on surfaces, in your yard, and on your dog’s coat. While your dog is being treated, bathe them regularly to remove cysts from their fur, disinfect food and water bowls daily, and clean up stool from your yard promptly. Hard surfaces can be cleaned with diluted bleach. Cysts don’t survive well in hot, dry conditions, so good ventilation and sunlight help too.

Is giardia contagious to other pets and humans?

Yes, giardia is contagious to other dogs and some other animals. If you have multiple pets, your vet may recommend testing (and possibly treating) all of them, even if some appear symptom-free.

As for humans: giardia is technically zoonotic, meaning it can pass from animals to people. That said, the strains most commonly found in dogs are not the same strains that most commonly infect humans, so the risk of your dog passing giardia to you is considered low but not zero. The main precaution is basic hygiene: wash your hands thoroughly after handling your dog’s stool, cleaning up their space, or bathing them during treatment. Immunocompromised individuals, young children, and the elderly should take extra care.

How to prevent giardia in dogs

You can’t bubble-wrap your dog, but you can reduce their risk with a few consistent habits:

• Don’t let your dog drink from puddles, ponds, or shared water bowls at dog parks
• Bring fresh water from home on outdoor adventures
• Pick up your dog’s stool promptly to avoid environmental contamination
• Keep your dog’s living area clean and dry
• After boarding, grooming, or visiting a dog park, monitor for any changes in stool for a week or two
• Schedule regular fecal tests at your vet’s recommendation, especially if your dog spends time around other dogs

There’s no vaccine for giardia in dogs, so prevention is really about limiting exposure and staying observant.

Does pet insurance cover giardia in dogs?

Treating giardia isn’t usually a single vet visit. Between the initial fecal test, medication, follow-up stool samples, and sometimes a second round of treatment, the costs can add up faster than you’d expect, especially if your dog is a repeat case or has other health complications alongside the infection.

Lemonade dog insurance can help cover the cost of diagnosing and treating giardia, as long as it’s not a pre-existing condition and symptoms first appear after your 14-day illness waiting period. The base policy covers things like diagnostics, treatments, and medications, but you can enhance your coverage with one of our add-ons, like the Visit Fee add-on.

The catch, as with any insurance, is that you need to have coverage in place before your dog gets sick. A policy you set up today won’t help with a diagnosis that happened last week, but it could make a real difference the next time something comes up.

Before we go

Giardia is one of those things that sounds scarier than it usually is. It’s common, it’s treatable, and most dogs come through it just fine. The key is getting a proper diagnosis from your vet rather than waiting it out or trying home remedies, because the right medication makes all the difference. If your dog is showing signs of giardia right now, call your vet, bring a stool sample, and follow through on the full treatment and follow-up protocol. And if you don’t already have pet insurance, it’s worth thinking about before the next vet visit, not after.

Frequently Asked Questions

A few quick words, because we <3 our lawyers: This post is general in nature, and any statement in it doesn’t alter the terms, conditions, exclusions, or limitations of the policies issued, which differ according to your state of residence. You’re encouraged to discuss your specific circumstances with your own professional advisors. The purpose of this post is merely to provide you with info and insights you can use to make such discussions more productive! Naturally, all comments by, or references to, third parties represent their own views, and Lemonade assumes no responsibility for them. Coverage may not be available in all states. Please note that statements about coverages, policy management, claims processes, Giveback, and customer support apply to policies underwritten by Lemonade Insurance Company or Metromile Insurance Company, a Lemonade company, sold by Lemonade Insurance Agency, LLC.  The statements do not apply to policies underwritten by other carriers.