Giardia

Giardia is a parasite that can live in the intestines of mammals, birds, and amphibians.  There are many subspecies of Giardia that each target a specific group of animals, but all the subspecies have the same life cycle and mode of transmission.  The lifecycle of this parasite is made up of two stages:  mature parasites and cysts.  The mature parasite lives in the small intestine where they multiply and eventually become cysts.  Cysts are the infective stage and are shed into the feces of the infected animal where they can survive for several weeks (and even up to 2 years in some cases!!!) in the environment as cysts, and are then ingested by their “host” and turn into a mature parasite and repeat the cycle. 

Your dog could be that unsuspecting host that drinks water or eats something that has been contaminated by feces.  Once the parasite is in your dog’s intestines, he can spread it even if he doesn’t show any signs of illness or infection.  This is especially worrisome if you have more than one pet in your household.  Transmission from dogs to cats is possible but unlikely, whereas transmission from dog to dog is quite common. 

Not all dogs show signs of this parasite, but when they do, it is unpleasant.  The most common symptom is diarrhea.  This is due to the fact that the parasite inhibits your dog’s ability to properly absorb nutrients, water, and electrolytes.  The diarrhea can be intermittent or continual, and failure to diagnose and treat the disease can lead to severe weight loss, and potentially death in extreme cases.  Along with diarrhea and weight loss, you may see vomiting, dehydration and poor coat appearance.  If you notice any of these symptoms, you should call your vet. 

To diagnose Giardia, your vet may conduct fecal diagnostic tests in-house or a sample may have to be sent to a reference laboratory.  Drugs often used to treat it include Fenbendazole and Metronidazole.  Supportive treatment may be needed if severe diarrhea or dehydration are present.  All infected pets should be retested 2-4 weeks after completion of treatment.     

While we may not be able to control every aspect of a dog’s environment, there are some things we can do to prevent Giardia in dogs.  Always make sure your dog has clean water available, making them less likely to drink from infected puddles.  Picking up after your dog as soon as possible will prevent cysts from entering the environment.  Try not to bring your dog to places where there are large amounts of dog feces, as this will limit the possibility of exposure.  Unfortunately, your dog’s monthly flea/tick/heartworm preventatives do not protect them from this parasite.

Humans CAN contract Giardia, though the odds of getting it from your dog are fairly low.  Washing your hands after handling any dog poop will reduce that risk further.  Giardia in humans is more commonly transmitted through ingesting contaminated water or food.  Be especially careful about your drinking water while traveling and consider buying a water filter if your water source is known to contain the parasite.  Wash all produce before eating and wash your hands after working in the dirt. 

Prognosis for all is good in most cases as long as proper treatment is completed!