Intestinal parasites constantly threaten dogs, who can easily pick them up from contaminated environments. If your dog visits places where other dogs have been, they are at high risk for catching giardia—a single-celled protozoan parasite that infects up to 25% of social dogs in urban settings. The Premier Pet Hospital team created this guide to help pet owners understand their dog’s risk and dispel common myths and confusion surrounding this common organism.
What is giardia?
Giardia is a single-celled protozoan parasite that infects dogs, cats, humans, and many other species. While giardia exists as a single species or strain, the parasite has multiple “assemblages” or forms that each infect different animals. Once the giardia infects a host, the trophozoite form attaches to the intestinal walls, damages the intestinal lining and cells, and causes watery diarrhea and abdominal discomfort. However, many infected dogs have an asymptomatic infection and do not develop diarrhea.
How does giardia infect dogs?
Dogs and other species contract giardia when they ingest the infective form (i.e., giardia cyst), which is passed in infected feces. Cysts may be present in water, soil, or surfaces contaminated with an infected pet’s stools or on the fur. Studies show that giardia is the most common parasite in dogs, with up to 15% of dogs with diarrhea testing giardia infection-positive. Dogs who spend time in urban areas that other dogs frequent or who go to daycare, dog parks, boarding, or grooming facilities are at higher risk for contracting giardia than home-bound dogs.
How do veterinarians test dogs for giardia?
Giardia cysts can be detected on a routine fecal flotation test—the same test our veterinary team recommends for all dogs and cats, and the reason we ask you to bring a stool sample to your veterinary appointments. When the cysts aren’t detected in a sample, but our team has a high suspicion of infection, we can also run antigen or PCR tests, which detect giardia’s genetic material. After treatment, the antigen or PCR test may remain positive for long periods, so repeat infections cannot be reliably detected.
Can I catch giardia from my dog?
Rarely, immunocompromised humans can pick up giardia from their dogs, but those with normal immune systems are extremely low-risk, because each giardia form typically prefers a different host species. Therefore, humans usually transmit the disease to other humans, and dogs transmit the disease to other dogs.
How do you get rid of giardia in dogs?
Treatment is recommended for all infected dogs who are showing symptoms. The Companion Animal Parasite Council (CAPC) and other leading veterinary organizations do not recommend treating asymptomatic pets routinely, but the decision depends on several factors. We may choose to treat an asymptomatic pet if other pets or people in the household are high-risk, or if the pet is highly social and could pass the disease to other susceptible animals.
Treatment usually involves one or two three- to five-day medication courses, each followed by a repeat fecal flotation test to ensure resolution. Treatment is focused on resolving symptoms and not necessarily eradicating infection, which may persist in a few dogs.
Can my dog become re-infected after treatment?
Re-infection is common in dogs and can occur shortly after the initial infection if giardia cysts remain on the dog’s fur or in the environment. The best prevention is ensuring good sanitation during and after your pet’s treatment, including removing all feces, trash disposal, washing bedding, cleaning surfaces with steam or disinfectants, and bathing your pet on the last day of treatment.
How do I prevent giardia infection in my dog?
Giardia is highly prevalent in dogs and the environment, so avoiding infection altogether is tricky. If your dog has a pre-existing intestinal disease or a condition that compromises their immune system, you should avoid places that other dogs frequent. Do not let your dog drink standing or natural water sources or eat another dog’s feces. While giardia can cause chronic or intermittent diarrhea in some dogs, most recover completely from the infection once identified and treated.
Because giardia is everywhere in the environment and often carried by asymptomatic dogs, you can never completely eliminate your pet’s risk. Scheduling routine wellness examinations and fecal parasite checks with the Premier Pet Hospital team will help identify active giardia infections and prevent your dog from developing diarrhea or spreading the illness. Call us to schedule your pet’s next visit, or if you have questions about giardia testing and treatment recommendations for your dog.