Giardia Vaccine for Dogs

Giardiasis can spread quickly in crowded dog kennels.
i Homeless dog in Kennel image by dinahr from

If your dog has acute diarrhea, vomiting and weight loss she may have giardiasis. Sometimes mistaken for worms, this is a parasitic infection that can affect you as well as your dog. Various treatments are available, including a vaccine. However, some vets dispute the benefits of giving a routine vaccination.

Sources Of Giardia

Giardia parasites are most often found in water, and it isn't always dirty water as you might expect. They may live anywhere from a mountain stream to a muddy creek. Although your pet is unlikely to catch it from your tap water, the parasite has been traced to city water systems. For example, outbreaks of giardiasis may occur after heavy rains have overstretched the water filtration system. Keeping your dog away from ponds and streams is one way you can prevent her getting this infection. Keeping your yard free of feces, and your dog away from the feces of other dogs or cats, is another preventative step. Feces carrying the giardia parasite is a secondary source, as the parasites survive an infected dog's digestive system and pass out in her stools. This is one reason giardiasis is prevalent in a crowded kennel environment.

Giardia Standard Treatments

If your vet diagnoses giardiasis, he is likely to prescribe an eight-day course of the antibiotic metronidazole. Because giardia parasites aren't bacteria, an antibiotic works. This treatment approach is identical to the one your doctor would prescribe for you if you contract giardiasis. Giving metronidazole is effective in some 67 per cent of cases, according to "The Canadian Veterinary Journal," but you need to watch out for any side effects, such as anorexia, lethargy and weakness in her limbs. Fenbendazole is another standard treatment and studies show that it has a success rate of between 90 and 100 percent, "The Canadian Veterinary Journal" reports.

Giardia Vaccine

In the late 1990s a licensed vaccine appeared that is exclusively for use with dogs. The idea of the vaccine is to prevent giardiasis, but vets also use it as a treatment, particularly if the dog has recently been exposed to sources of giardiasis. The vaccine reduces the amount of giardia parasites an infected dog sheds through her feces, and therefore reduces the spread of this infection. However, some vets believe that there is insufficient evidence to justify use of a vaccine, particularly in dogs without symptoms. You should talk to your vet about the vaccine and get his perspective on whether or not to have your puppy or adult dog vaccinated.


The key controversy is over giving the giardia vaccine as a matter of routine along with other pet vaccinations. Some dogs carry giardia parasites without showing any symptoms. However, a 2002 clinical study in Ontario showed that there was no significant difference in the levels of parasites present between dogs given the vaccine and those given a placebo. So, the veterinarians concluded that giving a giardia vaccine -- one that contains inactive giardia parasites -- had no effect on asymptomatic dogs. David McCluggage, a vet at, believes that most puppies are exposed to giardia via the mother and that giving the giardia vaccine is pointless when the puppy's immune system has already had to deal with it.

Always check with your veterinarian before changing your pet’s diet, medication, or physical activity routines. This information is not a substitute for a vet’s opinion.

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