When you welcome a new puppy or dog into your family, it is important to have its stool tested for the presence of intestinal parasites. Some intestinal parasites are zoonotic, which means that they are transmissible to humans. One such parasite is giardia. Find out why giardia is so common in dogs, why it can be challenging to diagnose and how you can protect your family from contracting this parasite. 

What Is Giardia?

Giardia is a protozoan parasite that causes giardiasis, the intestinal infection that results once the parasite dwells in the host's gastrointestinal tract. Those that remain in your pet's intestine to feed and reproduce are called trophozoites. When the parasite load is high, some trophozoites transform into cysts, and these cysts are shed in the infected pet's stool. Each of these cysts contains two partially developed trophozoites, and the cysts can survive for several months in cool, moist environments. Giardia can infect the following:

• Dogs
• Cats
• Wildlife
• Humans

Contraction and Prevalence

Dogs contract giardia by sniffing or ingesting the cysts. This most commonly occurs by drinking stagnant water that has been contaminated by feces, by ingesting the stool from an infected animal and by licking the rear end of an infected animal, such as housemate. Once a cyst has been consumed, it breaks open to unleash the two trophozoites into the intestine. Giardia is a common finding in puppies and dogs that are acquired from puppy mills, pet shops and shelters that house a high number of animals and have a high turnover of incoming animals.

Diagnosis and Treatment

Diarrhea, which can present acutely, chronically or intermittently, is a classic symptom of giardiasis, but many infected dogs are asymptomatic. Combining this fact with the fact that cysts are not constantly shed presents a dilemma when it comes to accurate diagnosis. The routine fecal flotation test that reveals other intestinal parasites does not consistently reveal giardia cysts. The only way to definitively diagnose giardia is to perform a fecal giardia ELISA test, which detects the presence of giardia protein antigens. The treatment for giardia is typically a course of an antiparasitic drug called fenbendazole and an intestinal antibiotic called metronidazole, followed by repeated fecal flotation tests to confirm that no more cysts are being shed. Since your pet's system can take up to six months after treatment to be cleared of giardia antigens, the ELISA test can yield false positive results during this time.  

Preventative Measures

While your pet is being treated for giardia, diligent cleaning is the key to protecting your own health and that of your family. Human family members that are especially at risk for contracting giardiasis include the elderly, individuals with compromised immune systems, such as those who are undergoing chemotherapy or those who are positive for HIV, toddlers, and very young children. Remind all family members to wash their hands thoroughly after they have interacted with the infected pet, and discourage them from allowing the pet to lick their faces. Carry out the following cleaning tasks while your pet is being treated:

• Remove and dispose of all feces from the yard immediately each time your dog defecates.
• Launder all pet bedding with bleach each day.
• If your puppy defecates on a bleachable surface inside your home, clean the soiled area with a disinfectant bleach solution.

Don a new pair of disposable gloves each time you clean up after your dog.

Whether your dog frolics in the dog park, tags along on your woodland hikes or simply patrols the backyard through which wildlife has tread, parasites always loom in the environment. While many of the heartworm preventative products on the market offer additional protection against certain intestinal parasites, such as roundworms and hookworms, they do not offer protection against others, including giardia. This is why your veterinarian recommends a proactive approach in parasite control by having your dog's stool tested annually or, in some cases, every six months. This simple and inexpensive step will help to keep your entire family, the humans and the animals, healthy. Contact a local vet, such as one from Elizabethton Veterinary Clinic, for further assistance.