Signs & Symptoms of Giardia in Dogs

Giardia is a one-cell parasite that lives in the intestinal tract of dogs. While microscopic in size, this parasite is capable of causing serious illness.

Because giardiasis may cause a zoonotic infection, meaning humans can catch it, dog owners must be able to recognise potential signs and symptoms so they can begin treatment quickly.


Giardia is not a virus, bacteria or worm. Giardia is a protozoan parasite that can be found in contaminated waters such as streams or simply on contaminated grounds.


Not all dogs develop symptoms from giardia. However, dogs may develop various symptoms that can be often confused with other conditions.


The most evident symptom of giardia in dogs is a soft, often greenish, foul-smelling diarrhoea. Sometimes the diarrhoea may be explosive, and bloody with mucus.


In some cases, the signs of giardia may persist for several days or weeks causing malnutrition, loss of appetite, weight loss, dehydration, lethargy and even death. This is especially seen in vulnerable dogs such as debilitated adult dogs and puppies.


Because the symptoms of giardiasis may mimic several other conditions, it is important for the veterinarian to test specifically for giardia so that the antibiotic treatment of choice with metronidazole starts immediately. Diagnosis is often challenging because it is hard to detect the presence of giardia in fecal samples.