Posted by camille arneberg on

Treating and preventing Giardia in dogs

Table of Contents

What is Giardia in dogs and how do I treat it?

What is Giardia?

Giardia is a single-cell, microscopic intestinal parasite that can infect dogs, cats, humans, and other mammals including sheep, cattle, and even squirrels! The diarrheal disease caused when animals are infected with the Giardia parasite is referred to as giardiasis. Giardia can wreak havoc on the digestive system of a previously healthy pet. It exists in two forms over its life cycle - trophozoites and cysts. Both of these forms can be present in pet feces, but the trophozoite cannot survive in the environment outside of a host animal. Unlike trophozoites, Giardia cysts, protected by hard outer shells, can live outside of an animal host for an extended time, surviving longest in an environment with cool water. After dormant cysts are consumed, they travel to the small intestine where two trophozoites are released, allowing the parasitic infection cycle to repeat.

The CDC graphic below gives a simplified visual presentation about the life cycle of this pesky protozoa :



How do dogs get Giardia?

Dogs always get giardia through oral ingestion, but the specific exposure takes a variety of forms. Giardia infections in dogs are very common and very contagious! Because the cysts can survive for weeks up to months in the outside environment, drinking contaminated water is the most common way dogs (and humans) become infected with giardia. Your pet may also get giardia by licking themself after rolling around in disease affected dirt, chewing on a new,exciting, contaminated stick, or examining another dog's giardia infected feces a little too closely. Dogs housed in crowded kennels and well as young puppies are especially susceptible to giardiasis because their close living proximity, which increases exposure to feces with the disease.

Symptoms and Side Effects of of Giardia

The number one most common symptom of giardia in dogs is diarrhea -- this diarrhea may come on severely and suddenly, occur and seem to resolve itself repeatedly, or occur as a chronic condition over days several weeks. Some dogs will have feces that contains mucus, is soft, foamy, oily, and carries an extra foul smell. If giardia is left untreated, this parasite can cause dangerous weight loss and an array of intestinal problems. Giardiasis poses an acute health risk to senior dogs, growing puppies, and dogs with a weakened immune system.

In addition to diarrhea, giardia symptoms and side effects may include:

  • Failure to gain weight (especially dangerous in puppies)
  • Vomiting
  • Poor coat appearance
  • Dehydration
  • Malnutrition

Giardiasis in dogs can be tricky to catch because some dogs may not show any symptoms despite being infected with giardia. This is why it is important to include a fecal test as part of your dog's routine veterinary care to prevent missed infections. Puppies and younger dogs will usually have more visible symptoms than older animals. Because diarrhea causes stool to pass faster than usual, giardiasis prevents your dog from absorbing all necessary nutrients and electrolytes and also increases dehydration.

Treating Giardia in Dogs

If you think that your dog is showing clinical signs of giardia, you will want to make an appointment ASAP with a veterinary medicine professional for diagnosis and treatment. Bringing a fecal sample for your vet to test in the lab is a great, proactive step to get your dog diagnosed with giardia and rule out other potential causes of doggy diarrhea.

In some cases, a fecal flotation test performed with zinc sulfate may fail to detect the tiny giardia cyst present, resulting in a false negative test. If your dog has persistent diarrhea and/or weight loss and the fecal tests do not show giardia infection, your vet may still recommend going ahead with treatment. While giardiasis occasionally resolves itself, medical treatment is recommended to reduce harm caused by symptoms and ensure the infection is fully resolved.

Your vet may prescribe medication to quickly treat infected dogs. Fenbendazole and Metronidazole are two drugs that may be prescribed to remove giardia cysts and stop the parasitic infection cycle in your dog; they are usually taken by mouth for 5-10 days. Some research suggests that fenbendazole may be slightly more effective and is also used safely for treating giardia in pregnant dogs. Metronidazole is also a common giardia prescription for humans, but is not recommended for use in cats.

If your dog continues to exhibit signs of giardiasis or cyst are found in follow-up lab tests, a second round of treatment will be ordered -- oftentimes it will be more aggressive and include the use of both of these veterinary medications. Until the fecal lab tests come back negative and your dog is no longer showing symptoms of giardia, you should continue to work through a treatment plan with your vet. Giardia is usually fully resolved within 6-8 weeks, but symptoms may linger in some cases.

Another factor in successfully healing your pets giardiasis is treatment of their gastrointestinal system with high quality nutritional support. Often your vet will prescribe a bland diet along with a probiotic until your infected dog's stool returns to its normal, pre-infection consistency. This may take up to 10 days. Adding a high-quality probiotic to your dog’s regular diet can benefit your dog's digestion, increase their absorption of vital nutrients, and prevent the overgrowth of “bad” bacteria in their GI tract.

Natural Giardia Treatments for Your Dog

Many pet owners hit Google in search of a natural Giardia treatment or a home remedy for their dogs and cats. These treatments often suggest feeding your dog plants or supplements known to have anti-parasitic properties, like black walnut or grape seed extract. While a natural remedy may relieve your dog, they are often less effective than medication, take longer to work, and not regulated by the same standards as pet prescription options. If you are considering natural treatment for your pets, first consult with your vet for a diagnosis as well as to evaluate best options before beginning with natural treatment. Follow-up vet care and additional flotation tests ensure the giardia infection is fully treated and give your dog a clean bill of health.

Preventing Giardia Infection

A giardia preventative treatment is not offered in simple monthly tablet like flea, tick, and heartworm prevention. However, one of the top most effective methods to prevent giardia infection is even easier and should already be a part of your daily routine. Make sure that your dog always has 24/7/365 full-time access to fresh, clean drinking water. Staying adequately hydrated with non contaminated water will reduce the chance of your pup slurping a big gulp of a dirty standing water from a potentially contaminated source.

If you live in an area where Giardia is found in the tap water, purchase a filter to remove any cysts from the water - for the sake of both the human and dog members of your family. Adequate hydration with clean water is fundamental to so many crucial biological processes, and even slight dehydration can create signs of poor health. Clean H20 always ready to go? Your immune systems thank you in advance!


Trying to cover all your bases? Another fantastic method to prevent giardiasis in dogs and cats is to reduce their exposure to the feces of other animals -- avoid dog parks where people do not clean up quickly after their pet. Also, before deciding on a boarding or doggie daycare facility, ask how frequently they clean up after their guests, how often pets are taken outside, and which cleaning methods are used on the dog runs. You never know...their answers to these quick tests may cause you to head for the door!

Tips to Avoid a Reinfestation

Because it is highly contagious, all animals in a multi-pet home should be tested and treated quickly. Here are some useful guideline to best clean your home:

  • Use a potent disinfectant on hard surfaces, like Lysol, which contains quaternary ammonium and is known to cause the inactivation of giardia cysts.
  • Run all of your pet's food and water bowls through the dishwasher on the sanitize setting if possible.
  • Pet bedding (and human bedding if your dog sometimes mysteriously finds themself on your bed) should be washed and dried on the highest heat option.
  • Carpets and upholstery should be steam-cleaned in order to ward off lingering cysts.

While, it is impossibly to 100% eradicate all giardia from your home environment, completing these steps will greatly reduce the risk of reinfestation.

Give your dog at least one long, thorough bath by the halfway point of their treatment as well as another deluxe scrub session at treatment's end. Wear gloves if possible and definitely wash around their anus, where cysts are most likely to be clinging to their fur. Bathing is supremely important in preventing reinfection with giardia. Giardia is already contagious enough between dogs -- you definitely don't want your newly cured dog giving themself another infestation!

Can infected animals pass giardia to humans?

The short answer is “yes,” but giardia transmission from pet to humans is very rare. It is highly unlikely that you well get giardia from your dog licking you. Even though giardia may be the most common gastrointestinal parasite infecting human beings, the strains that target people are different than the species usually diagnosed in pets. Moreover, the only known route of infection is oral ingestion, so common hygiene habits like hand washing and avoiding touching your face go a long way.

To further reduce this small risk, wear gloves when picking up poop and wash your hands ASAP with an antibacterial soap as soon as you finish cleaning up after your dog. Wear gloves when working in the yard or garden to avoid contact with contaminated soil. Preventing infection in your dog and aggressively avoiding reinfection is crucial to stopping the giardia life cycle in its tracks and protecting the health of everyone in your family.


Sources: