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If your dog has been having tummy issues and you can't figure out the cause, they could have giardiasis, an infection caused by tiny parasites called giardia. Giardia is among the most common intestinal parasites reported in dogs, but they can wreak havoc on your dog's digestive system.
Here's everything you should know about giardia in dogs, including how a veterinarian identifies them and giardia in dogs treatments.
What Is Giardia?
Giardia requires a host — in this case, a dog — to live and multiply. There are two forms of giardia: the single-celled trophozoite (parasite) that swims around and lives in the small intestine of mammals, and the other is a cyst, or egg. A cyst passed in the feces of an infected animal is considered immediately infectious to other animals. Dogs contract giardiasis when they ingest a giardia cyst, either directly from the soil or from contaminated water.
Giardia are found everywhere in the U.S. but are more common in the western U.S. and in wet areas. Dogs living in stressed or crowded conditions, like animal shelters, have a higher risk of contracting the infection due to the close proximity they have to other dogs.
How Giardia in Dogs Gets Diagnosed
Giardia in dogs can be tricky to diagnose because, while in some cases, it can cause gastrointestinal issues (usually diarrhea), but in other cases it won't cause any problems at all. Doggy diarrhea as a result of giardia can either come on suddenly, come and go, or last for a long time. Giardia in dogs is probably far more common than we realize both because it doesn't always cause health issues and because giardia organisms can be tough to identify.
Your vet will be able to diagnose your dog with giardiasis either by identifying giardia organisms or giardia antigens in your dog's feces. Go with whichever test your dog's vet recommends; they may even recommend both tests since giardia are notoriously difficult to find in fecal samples. In fact, you may have to bring in several samples before the vet can find the critters.
If your dog has chronic diarrhea and the vet can't find giardia, they may still recommend giardia treatment if they suspect your dog is infected.
Treatments for Dogs with Giardia
Treatment of giardia in dogs includes treating diarrhea and upset stomach and eliminating the giardia infection. Your dog's vet will likely prescribe one or more medications to eliminate giardia from their system. These medications could include fenbendazole and/or metronidazole. Don't be surprised if the vet wants to retest your dog after treatment to ensure that the giardia have been eliminated, or if they suggest treating all pets in your household to ensure that none of them are carrying giardia that could reinfect your dog.
Another aspect of treating giardia in dogs is supporting the healing of the gastrointestinal tract through nutritional support. A dog who's been diagnosed with giardia has a weakened, inflamed gastrointestinal system, so proper nutrition is an essential part of treatment. The vet will likely recommend feeding your dog a bland food that's easy to digest and that promotes intestinal healing. It's generally recommended that you feed your dog bland food until their stool returns to normal consistency; this typically takes anywhere from three to 10 days.
Dogs infected with giardia can also have imbalances in their gut bacteria, otherwise known as the microbiome. If the vet suspects an imbalanced microbiome, they may even recommend a therapeutic dog food specifically formulated to promote good gut bacteria within the microbiome for your dog. Always follow the vet's instructions, make sure your dog finishes all medications and call the vet if you don't see your dog improving with treatment.
It's very important to know that humans can also contract giardiasis. If your dog has been diagnosed with or is suspected to have the infection, protect yourself by wearing gloves when you handle their feces (always a good idea regardless) and wash your hands thoroughly afterward.
Giardia in dogs can be a nasty experience for your pooch or it can involve no signs of infection at all. Either way, with proper testing and treatment, your dog's vet can help you eliminate the parasites from your pet's system and get them back to feeling like themselves.
Dr. Sarah Wooten
Dr. Sarah Wooten graduated from UC Davis School of Veterinary Medicine in 2002. A member of the American Society of Veterinary Journalists, Dr. Wooten divides her professional time between small animal practice in Greeley, Colorado, public speaking on associate issues, leadership, and client communication, and writing. She enjoys camping with her family, skiing, SCUBA, and participating in triathlons.