How Giardia Affect Dogs

Many dogs infected with Giardia have a latent or subclinical infection, which means that they really don’t show any noticeable symptoms of illness. However, the parasites eventually damage the lining of the intestines of the animals that they infect, disrupting digestion and using up nutrients that the animals need for normal health. The effects of Giardia are most pronounced in young dogs, old dogs and those with impaired immune systems. The profuse diarrhea that frequently accompanies giardiasis usually also causes severe dehydration. Giardiasis can be fatal, although that is quite uncommon in North America.

Symptoms of Giardia

Giardia can cause a number of gastrointestinal symptoms in domestic dogs. Owners may notice one or more of the following:

• Loss of appetite (inappetance; anorexia)
• Weight loss
• Bloody stools (hematochezia)
• Pale-colored stools
• Greasy stools (steatorrhea)
• Diarrhea (can be acute, chronic or intermittent; often poorly formed or loose stools; often profuse and watery)
• Gas (flatulence)
• Abnormally strong-smelling (malodorous) stools
• Abdominal pain (cramping; nausea)
• Lethargy (tiredness)
• Weakness
• Dehydration (can be severe)
• Fever (occasional; not common)
• Vomiting (occasional; not common)

Dogs at Increased Risk

Dogs of any age, breed or gender can become infected with Giardia. Young animals, and those confined in close quarters with a number of other animals, seem to be more susceptible to infection, as are dogs whose immune systems are stressed or otherwise compromised.