Causes of Giardia in Dogs

Common causes of giardia in dogs includes drinking from a lake, pond or stream. Dogs get the infection when they drink water that contains trace amounts of animal feces. The feces contains a cyst or small sac that enters the gastrointestinal tract of the dog.

The cysts are the causes of giardia in dogs as they change into protozoa that divide in two rapidly. The protozoa attach to the small intestine where they produce disease by taking away nutrients from your dog. The protozoa also produce harmful substances. Left untreated, Giardia can damage the lining of the small intestine and cause scaring.

The disease is sometimes called Beaver Fever since beavers are known carriers of giardia. These are also the most commonly diagnosed protozoa in humans.

Coccidia is a similar parasite that affects the intestinal tract. Unlike the causes of giardia in dogs from lakes and streams, coccidiosis is contracted by eating feces directly.

Symptoms of Giardia in Dogs

Giardia interferes with the absorption of nutrients from food. As can be expected, when you don't get the nutrients you need, you lose weight and appear to have less energy.

Dogs with giardisis may have no symptoms or diarrhea. Diarrhea tends to be bad smelling and very watery. Diarrhea may be bad or light and occur frequently or far apart.

Diagnosis of Giardia in Dogs

Your veterinarian will either study a stool sample or take a swap and wipe it at your dogs rectum. It is possible that the swap will not show any causes of giardia in dogs, yet your dog still has the disease. Your doctor will take 3 samples collected at least 2 days apart. There are also new blood tests that can detect the disease (called ELISA or IFA).

Treatment of Giardia in Dogs

The drug metronidazole (trade name Flagyl)is effective against giardia and is given over 5 to 7 days. This drug should not be given to pregnant dogs as it is known to cause problems with the fetus. Metonidazole also has a positive effect on other causes of diarrhea. A complete list of treatments follows:

Metronidazole (Flagyl,25-30 mg/kg, 7 days)
Furazolidone (Neftin, 4 mg/kg, 10 days)
Tinadazole (44 mg/kg once daily, 7 days)
Fenbendazole (Panacur 50 mg/kg once daily, 3 days)
Albendazole (Valbazen, 25 mg/kg, 2 days)

Other treatments include adding fiber to your dogs diet.

Dogs do not acquire immunity to giardia after treatment, so they can contract the disease again. There is a vaccine to prevent the disease.

Prevention of the Causes of Giardia in Dogs

The only way to prevent giardia is to eliminate the source of the infection which is water.

Any place water collects should be removed if possible such as places where their are puddles or poor drainage. Any concrete surface should be cleaned, dried and sealed. Gravel areas should be replaced. Bleach may help clean infected areas (1% bleach, 99% water). Lysol, ammonia, and bleach can also be effective decontamination agents. Look for products that contain quaternary ammonium compounds.

Removal of Giardia is difficult. They survive chlorination of drinking water and freezing down to �13oC.

Sources:Michael R. Lappin, DVM,PhD, DACVIM
Professor
Department of Clinical Sciences
Colorado State University

Kuenzi Family Pet Hospital
Rodney S. Kuenzi, D.V.M.

GUARDING AGAINST GIARDIAMaggie Fisher BVetMed MRCVS

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James M. Giffin
Liisa D. Carlson DVM

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Betsy Brev itz, DVM

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