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Giardia

2 min readLast reviewed Jul 3, 2026 by JWB

How pets get it

Giardia lives as cysts in the environment, especially around standing water, dog parks, boarding kennels, and puppy mills. A pet drinks contaminated water or licks contaminated paws and the cysts hatch in the small intestine.

Signs to watch for

  • Soft, pale, mucus-coated stool that comes and goes
  • Greasy appearance or strong odor
  • Intermittent diarrhea in an otherwise bright puppy
  • Weight loss or failure to gain weight despite good appetite

Diagnosis and treatment

Diagnosis usually combines a fecal antigen test (ELISA) with a fresh fecal exam because cysts are shed intermittently. Treatment is prescription-only — do not attempt to treat with home remedies. Environmental cleanup and bathing the pet at the end of treatment matter as much as the medication.

Why it matters

Giardia is one of the most common causes of stubborn puppy diarrhea and the reason 'my dog keeps having soft stool but seems fine' warrants a fecal test, not another bland-diet week.

Frequently asked questions

Can I catch Giardia from my dog?
The dog and cat strains rarely infect humans, but immunocompromised people should still avoid handling infected stool without gloves and should wash hands thoroughly.
Does a negative fecal test mean my dog is clear?
Not always. Giardia sheds intermittently. If suspicion is high, vets often repeat testing or run a fecal antigen ELISA.

Sources

  1. Companion Animal Parasite Council, Giardia in dogs · verified 2026-07-03
  2. Merck Veterinary Manual, Giardiasis in animals · verified 2026-07-03

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