Part of your pet’s annual wellness visit includes a stool check done at the lab. This test looks for the presence of intestinal parasites such as roundworms or whipworms, using a process called fecal flotation, or fecal float. The test uses a special solution that causes any eggs present to float to the surface and stick to a slide, which is then examined under a microscope. This method also identifies the cysts present in a giardia infection.
The second part of the test is an immunology test known as ELISA. An ELISA test detects immune response by the body, and can be used to diagnose pregnancy, identify viral infection or exposure to an infectious microbe. In the fecal tests that we routinely send to the lab, the ELISA test identifies if a patient has been exposed to the parasite giardia.
Giardia is a flagellated protozoan parasite that lives and reproduces in the intestinal tract of several species of vertebrates. Giardia is the most common pathogenic parasite among humans world wide. An informal survey of the stool samples we submit for laboratory testing indicated that a full third of samples test positive for one or more parasites, with giardia being the most common one.
Giardia is spread primarily through contaminated water and is very easy to become infected with. Dogs and outdoor cats are more likely than indoor cats to become infected. When an animal walks in a puddle, especially after rainfall when giardia is concentrated in puddles, and then licks his feet, he becomes infected. Some pets like to drink directly from puddles, which is another method of infection. Cysts can also be inhaled or swallowed from infected feces. Once infected, an animal can continue to spread the parasite by using community water bowls at dog parks or kennels, and also by shedding cysts in their own stool.
Indoor cats can be infected by sharing water bowls with animals that go outside, or from drinking standing water in decks or from houseplants.
It is important to note that giardia infection does not always result in diarrhea or vomiting. While both of these symptoms are typical of giardia infection, many animals are asymptomatic. The only reason we know they are infected is by sending out the yearly stool sample for examination.
Pets that test positive need to treated even if they do not have vomiting, diarrhea or weight loss. Over time, the infection will worsen. Dogs and cats that have an asymptomatic giardia infection are more likely to suffer from diarrhea when placed under stressful situations, such as boarding. Most importantly, infected animals can continue to shed the parasite into their environment and infect others. As previously mentioned, giardia is a parasite that can infect humans as well as cats and dogs!
Treatment for giardia is generally done with oral medication lasting for 5 to 7 days. Pets with resistant infections will need longer courses of treatment and pets that also have vomiting and diarrhea will need support to resolve these symptoms.
To prevent giardia infection, never let your dog drink from puddles. If you are outside walking your dog after rainfall, stay on paths and away from standing water. Don’t let your dog sniff feces from other animals and always pick up after your own dog. Carry your own water for your dog on hot days. Pet stores sell light weight collapsible bowls in nylon or other fast dry fabrics. Finally, even if your pet seems perfectly healthy, have a stool check done at least once yearly to look for intestinal parasites.