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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.
What Is Giardia in dogs?
Giardia is a microscopic parasite that can affect humans, as well as dogs and cats. Like most parasites it needs a host, in this case we’re talking about dogs, to complete its life cycle. Infected animals shed giardia eggs, known as cysts, into the environment in their stools. These cysts may be found on grass or in water, such as puddles. When they are ingested by the next passing dog, they hatch and reproduce very quickly in the intestines.
Giardia can be found in most countries in the EU and UK but is more prevalent in some countries than others. 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 and the higher number of cysts being shed into their environment.
Symptoms of giardia in dogs
Although giardia infects lots of dogs, it doesn’t cause signs and symptoms in the majority of them. Most dogs can appear completely healthy and still be shedding cysts into the environment. Dogs with low levels of infection or healthy immune systems may simply tolerate the parasite and not have gut damage and inflammation resulting in diarrhoea. It’s one of the reasons that giardia is probably underdiagnosed because healthy dogs are not routinely tested for it. Those dogs that do have clinical signs tend to have soft stools or watery diarrhoea. This can come and go, too, adding to the difficulties of diagnosis. In severe cases, they will lose weight due to the excess losses from diarrhoea. Dogs that are young, geriatric or immunosuppressed are likely to be the worst affected.
Your vet will be able to diagnose your dog with giardiasis either by identifying giardia organisms or giardia antigens in your dog's faeces. Go with whichever test your dog's vet recommends; they may even recommend both tests since giardia are notoriously difficult to find in faecal samples. In fact, you may have to bring in several samples before the vet can find them.
If your dog has chronic diarrhoea and the vet can't find giardia, they may still recommend giardia treatment if they suspect your dog is infected.
Treatments for giardia in dogs
Treatment of giardia in dogs includes treating diarrhoea 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 food that's easy to digest and that promotes intestinal healing. It's generally recommended that you feed your dog this therapeutic 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. That said, it is rare for dog and cat giardia to spread to humans. We are actually more likely to be a source of infection to our pets! To be on the safe side, if your dog has been diagnosed with or is suspected to have the infection, protect yourself by wearing gloves when you handle their faeces (always a good idea regardless) and wash your hands thoroughly afterwards. Tell your GP if you develop any gastrointestinal signs.
Giardia can be a nasty experience for your dog 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.
Contributor Bio
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.
Reviewed by Dr. Emma Milne BVSc FRCVS, and Dr. Hein Meyer, DVM, PhD, Dipl-ECVIM-CA
