By Dial A Vet Veterinary Team
Giardia is a microscopic parasite that lives in the intestine. Some dogs carry it with few signs. Others develop soft stools, greasy foul-smelling diarrhoea, gas and weight loss, especially puppies and stressed or kennelled dogs. Because cysts survive in water and on surfaces, hygiene at home matters as much as veterinary treatment.
Key takeaways
- Giardia spreads via cysts in faeces that contaminate water, grass, bowls and coats.
- Intermittent diarrhoea is common; stools may look soft, pale, greasy or mucus-covered.
- Diagnosis usually needs specific faecal tests; a single routine smear can miss it.
- Bathe the rear end and wash bowls during treatment to reduce reinfection.
- Related: diarrhoea in dogs, my dog has diarrhoea, long-term diarrhoea, worms in dog poop.
How dogs get Giardia
Dogs ingest cysts from contaminated water, shared parks, sniffing faeces, or grooming cysts stuck in fur. Crowded environments raise risk. Not every exposed dog becomes sick; immune status and parasite load influence signs. People can occasionally be infected with Giardia species, so handwashing and prompt faeces clean-up are sensible, especially around children.
Cysts can survive in cool water, which is why puddles, creek edges and shared water bowls feature in many histories. Dogs that eat faeces are at higher risk and need behaviour and hygiene strategies alongside medication.
Signs to watch for
- Soft stool or diarrhoea that comes and goes
- Extra foul or greasy-smelling faeces
- Excess gas and a swollen-looking belly
- Weight loss or poor appetite in ongoing cases
- Scooting or a messy rear coat from diarrhoea
Vomiting can occur but is less constant than diarrhoea. Blood in stool or extreme lethargy suggests other or additional problems needing prompt care. Compare also colitis in dogs and supportive diarrhoea care, remembering that home diets do not clear Giardia alone.
When it is an emergency
Seek urgent veterinary care for continuous watery diarrhoea, repeated vomiting, collapse, pale gums, a painful hard abdomen, or a puppy that will not drink. Dehydration develops quickly.
How vets diagnose Giardia
Your vet may request fresh faeces for antigen tests, flotation with special solutions, or PCR panels, sometimes on more than one sample because shedding is intermittent. They will also consider dietary upset, other worms, bacterial causes and pancreatitis lookalikes. Bring a sample in a clean container the same morning when possible. Broader parasite context: parasites in dogs.
Treatment overview
Veterinary medicines that target Giardia are prescribed case by case. Some dogs need repeat courses if signs and tests persist. Do not use leftover human medicines. Your vet will advise on diet during recovery, which may include a temporary highly digestible food. Follow-up testing is sometimes recommended for stubborn cases or multi-dog homes. Complete the full course even if stools improve mid-way.
Home hygiene to cut reinfection
- Pick up faeces immediately and dispose of them securely.
- Wash food and water bowls daily with hot soapy water.
- Bathe the dog, especially the hind end, at the start of treatment as your vet suggests, so cysts on the coat are reduced.
- Wash bedding on a hot cycle where fabric allows.
- Limit shared water sources at the park during outbreaks when practical.
- Wear gloves if you have cuts on your hands, and wash hands afterward.
- Clean yards of faeces daily during treatment windows.
Prevention
Avoid letting dogs drink from stagnant puddles when you can offer fresh water instead. Maintain routine worming and faecal checks as advised. Quarantine new dogs with diarrhoea until tested. Keep yards cleaned, especially in boarding and daycare settings. After rain, be extra mindful of puddle drinking on walks.
FAQ
Can my dog give Giardia to me?
Zoonotic transmission is possible but not the most common household event. Hygiene lowers risk. Speak with your doctor if a person in the home develops prolonged diarrhoea.
Does every dog with soft stool need a Giardia test?
Not automatically, but testing is wise when diarrhoea lasts, returns, or appears in multi-dog homes and puppies.
Will probiotics cure Giardia?
They are sometimes used as supportive care but do not replace specific treatment prescribed by your vet.
Can Giardia survive in chlorinated pools?
Cysts are relatively hardy; discuss swimming restrictions with your vet during active diarrhoea.
Talk with a vet
If your dog has ongoing or foul diarrhoea, a Dial A Vet veterinarian can help you decide on urgency and what samples to prepare for your local clinic. Book a Dial A Vet consult.
References
- Merck Veterinary Manual. Giardiasis in Animals.
- Companion Animal Parasite Council. Giardia guidelines (discuss local application with your vet).
- WSAVA. Gastrointestinal parasite resources for clinicians and owners.
Disclaimer: Educational only. This page does not replace an examination or advice from your own veterinarian. If you are worried about your pet right now, contact your local vet or nearest emergency animal hospital.
