Dogs can easily transmit giardiasis when interacting with their canine companions at a dog park or drinking from a natural water source. The infection can result in significant gastrointestinal (GI) upset. To learn about this concerning canine condition, read our Urgent Pet Care Omaha team’s guide to giardiasis. 

Giardia is a parasite

Giardia duodenalis is a single-celled microscopic protozoan parasite that has at least eight genotypes (i.e., strains). The genotypes are classified A through H, with C and D being predominant in dogs. 

The parasite has two forms: the trophozoite and the cyst. The trophozoite is the parasitic stage that attaches to a dog’s intestinal wall to leach the host’s nutrients. The cyst is the infective stage that a dog passes in their feces. The cysts’ tough outer shell allows them to live for months in the environment, where other animals often ingest them and contract the disease. 

Giardia is highly contagious

Giardia cysts are ubiquitous in the environment. A dog can contract giardiasis in numerous ways, including by:

  • Ingesting infected fecal material
  • Ingesting fecal-contaminated soil or plants
  • Drinking contaminated water
  • Sniffing an infected dog’s hind end
  • Rolling on contaminated soil and grooming their fur afterward
  • Eating infected small animals

Giardia can cause gastrointestinal problems in dogs

Trophozoites attach to the wall of a host’s small intestine, damaging the cells. By doing so, trophozoites inhibit intestinal cells’ ability to absorb nutrients, which may also alter the normal flora and produce digestion-disrupting toxins. After infection, a dog’s signs typically manifest in about 5 to 12 days and may include watery, foul-smelling diarrhea, lethargy, vomiting, and excessive gas. A puppy or dog who has a weakened immune system has the highest risk for experiencing severe signs. Dogs can also be subclinical Giardia carriers, exhibiting no illness signs. However, these pups shed the parasite in their feces, contaminating the environment and posing a risk to other animals. 

Giardia can be difficult to diagnose in dogs

Because they are microscopic, Giardia cysts can be difficult to identify, because dogs shed them intermittently, which sometimes complicates diagnosis. Your veterinarian may perform diagnostics, such as a complete blood count (CBC), biochemistry profile, and parvovirus test, to rule out other potential conditions. To make a definitive Giardia diagnosis, the Companion Animal Parasite Council (CAPC) recommends that veterinarians evaluate symptomatic dogs by performing these three tests:

  • Direct smear — A fresh fecal sample, preferably less than 30-minutes old, is evaluated under a microscope to detect trophozoites.
  • Zinc sulfate fecal floatation — This test helps detect Giardia cysts. 
  • Enzyme-linked immunoassay (ELISA) or polymerase chain reaction (PCR) assay — Specific ELISA or PCR assays are useful in diagnosing Giardia.

Serial testing performed over several alternating days may be necessary for your veterinarian to make a definitive Giardia diagnosis. If you have multiple household pets, our Urgent Pet Clinic Omaha team may recommend testing them all to determine if they need treatment. 

Giardia is typically responsive to treatment in dogs

To kill the parasite, medical treatment is necessary. Veterinarians typically prescribe an antibiotic and/or antiparasitic medication, and they may recommend supportive care, such as intravenous (IV) fluids, if an affected dog is dehydrated or has electrolyte imbalances. Although Giardia treatment is usually successful, failure can occur in some cases:

  • Reinfection — Dogs can easily be reinfected if they ingest Giardia cysts from their environment or while grooming. We recommend disinfecting areas where your dog rests, laundering their bedding, and steam cleaning upholstery and carpets. In addition, bathe your dog at the beginning and end of Giardia treatment.
  • Immunosuppression — Immunosuppressed dogs have an increased risk for Giardia, and their infections can be difficult to eliminate.
  • Sequestration — In some cases, Giardia sequesters in the gallbladder or pancreatic ducts, requiring prolonged treatment. 

You can reduce your dog’s Giardia risk

Although Giarda are ubiquitous, you can help your dog avoid infection. To reduce your four-legged friend’s Giardia risk, follow these tips:

  • Schedule regular wellness evaluations, so your veterinarian can evaluate your dog for conditions, such as Giardia, before the disease causes a severe problem.
  • Before boarding your dog at a kennel, ensure facility staff practice appropriate hygiene measures to prevent a Giardia outbreak.
  • When on outings, prevent your dog from coming in contact with other animals’ feces.
  • To limit parasites’ spread in the environment, immediately clean up after your dog, and dispose of their fecal waste appropriately.
  • Prevent your dog from drinking from natural water sources or communal water bowls, such as those left on the sidewalk.
  • Bring water and a portable bowl on outings, so you can offer your dog a drink when they are thirsty.
  • Prevent your dog from eating small mammals.

Giardia public health considerations

While humans can contract giardiasis, they are typically infected if they drink contaminated water. The strains that usually affect dogs are not believed to be infectious to humans, however, if your dog has Giardia, take these precautions:

  • Prevent children and immunocompromised people from handling your dog until the Giardia infection is cleared.
  • Wash your hands thoroughly after handling your dog or their feces.
  • Contact your primary care provider if you develop GI symptoms.

Giardiasis is a concerning condition, but you can reduce your dog’s risk. If your four-legged friend exhibits signs that indicate they may have contracted Giardia, contact our Urgent Pet Care Omaha team, so we can diagnose the problem and provide the care your pup needs.