In some countries, Giardia is a common water-borne parasite and the cause for many travelers’ diarrhea. This hardy protozoan is also a frequent canine diarrhea cause in the United States and globally. The parasite can live for long periods under the right conditions, waiting to infect its next canine host. Because Giardia spreads so easily, outbreaks in kennels and dog parks are common and can impact up to half of the dogs in a given population. 

Despite Giardia’s prevalence, many pet owners may not understand the differences between infections in dogs and in humans, how Giardia spreads, or their own dog’s risk. Our Neighborhood Veterinary Centers of Waller team dispels the myths surrounding Giardia in dogs.

Fact: Giardia is the most common intestinal parasite in dogs

Studies of various dog populations report anywhere from 8% to 25% positivity rates for the parasite, with up to 45% contracting giardiasis during a kennel outbreak. Giardia is the most common canine intestinal parasite, causing watery diarrhea in many cases. The highest disease prevalence is in dogs who go to dog parks.

Myth: People contract giardiasis from dogs

According to the Centers for Disease Control (CDC), people and dogs can both contract Giardia. However, the infection rarely spreads between these two species. Each Giardia variant infects a narrow species range. The variants that like to infect dogs rarely spread to people, and vice versa. Most dogs contract Giardia from other dogs, and people contract Giardia from other people. 

People and dogs with compromised immune systems, such as those undergoing chemotherapy, are at greater risk for Giardia infections, including infection passed from dogs to people or people to dogs. Although uncommon, this situation is theoretically possible.

Fact: Giardia spreads easily through dog populations

Unlike intestinal parasites that transmit infection through their eggs, Giardia is a single-celled protozoan that has two forms—the trophozoite and cyst. Trophozoites attach to their host’s intestinal walls and feed, eventually transforming into cysts that leave the infected dog’s body through their feces, and potentially infect other dogs. Giardia cysts are immediately infective when a dog passes them in their stools, easily contaminating a pet’s fur, bedding, yard, or environment. A dog who inadvertently ingests the microscopic, invisible cysts can become infected.

Myth: Dogs only contract giardiasis directly from other dogs

Although a dog who spends time with other dogs, such as at a dog park, daycare, or boarding or grooming facility, has the highest giardiasis risk, any dog can become infected. Giardia cysts can survive for several months in cool, moist environments, including soil, a lake, a pond, or even a large puddle. Any dog who comes in contact with cysts another dog or wild animal has passed through their feces can develop giardiasis.

Fact: Routine fecal examination can detect Giardia in dogs

To determine whether your dog has Giardia, our Neighborhood Veterinary Centers of Waller team examines a fecal sample, using a microscope to detect cysts. If your dog’s stools are too watery for a traditional exam, we can perform tests to detect Giardia genetic material, but these tests often show a positive result long after the infection has cleared. The best way to screen dogs and monitor them after treatment is for our Waller, Texas, veterinary team to perform a standard fecal floatation test.

Myth: All dogs infected with Giardia develop diarrhea

Many infected dogs do not exhibit signs, but they can still spread the disease to others. However, some dogs develop acute, intermittent, or chronic diarrhea that sometimes continues after treatment. Treatment consists of one or two antiprotozoal medication rounds until your dog’s signs resolve and our team can no longer detect Giardia cysts in your pup’s stools.

Fact: Dogs can become reinfected after clearing the Giardia infection

Your dog’s Giardia infection will not clear if their environment remains contaminated, and they can reinfect themselves after passing cysts into the yard or onto their fur. If your dog is diagnosed with giardiasis, you’ll need to take precautions to help prevent their reinfection. Follow these cleaning tips:

  • Disinfect floors and launder bedding. 
  • Wash water bowls daily.
  • Pick up stools immediately.
  • Give your pet a bath on their last treatment day.

All dogs have a Giardia risk. Depending on your dog’s lifestyle or because you have inadequately sanitized their environment during or after treatment, your dog can develop recurring Giardia infections. To determine whether your southeast Texas pet has contracted giardiasis or another common condition is causing their diarrhea, contact our Neighborhood Veterinary Centers of Waller team.