Giardia Treatment for Dogs

Medicines Vets Use

Your vet will choose a medicine based on your dog's age, health and whether this is a first or repeat infection. Common options include:^1,3,2

• A benzimidazole dewormer, given for several days. It's the first choice in Europe. A UK parasitologist recommends a 5-day course, as 3 days is often not enough.^3,5
• An antiprotozoal antibiotic of the nitroimidazole class, alone or together with the dewormer. It can cause nervous system side effects with long or high-dose use, so it's used with care.^3,8
• A combination dewormer that some vets use for Giardia.^1,4

Some dogs with diarrhea also get a high-fiber or digestive-support diet. Probiotics are sometimes added, but there's little reliable evidence they help.^1,2,3

Bathe Your Dog at the End of Treatment

Cysts stick to the fur, especially around the rear end, and dogs swallow them when they groom. Bathing with shampoo removes them. CAPC advises a bath on the last day of treatment, and European guidelines suggest bathing at both the start and end.^1,4,12 Pay extra attention to the area under the tail, and ask your groomer or vet about clipping long or matted hair there.^5,8 Wear gloves or wash your hands well afterward.

How to Clean Your House After Giardia

No disinfectant is officially registered to kill Giardia cysts, and the CDC notes that the cyst's tough shell helps protect it from chlorine bleach.^3,13 What works best is removing feces, cleaning, using a suitable disinfectant or heat, and then letting everything dry completely:^1,3,4

• Pick up stool at least daily, and bag and bin it.^1,7
• Clean hard floors, crates and kennels with soap and hot water first, then apply a quaternary ammonium ("quat") disinfectant. Most quats inactivate Giardia cysts. Leave it on for 5 to 20 minutes, or as the label directs, before rinsing.^3,8
• Steam-clean carpets, upholstery and dog beds, or machine wash bedding in hot water.^12,2,5
• Wash bowls and toys daily during treatment and for a few days after, in a dishwasher or by covering them in boiling water for at least a minute.^7,14
• Let surfaces dry fully, because drying kills cysts. A UK guide suggests keeping disinfected runs empty and dry for 48 hours.^1,5

Giardia in the Yard

Grass and soil can't be disinfected, and the CDC advises against putting bleach or quats on them.^7,1 Cysts last longest in cool, damp, shady spots, while sunlight and drying kill them.^7,2 Merck suggests treating a grass yard or run as contaminated for at least a month after an infected dog was last there.³ Pick up feces right away, remove standing water and give your dog a clean water bowl.^7,15

How Long Does Giardia Last?

Diarrhea usually improves during the course of treatment. In one trial, cyst numbers had dropped by at least 94% two weeks after starting treatment.⁹ Some dogs need a second course or a different medicine.^5,1 Without treatment, some dogs carry Giardia and shed cysts for weeks to months.^4,6

Retesting After Treatment

If your dog's diarrhea has cleared, retesting usually isn't needed. CAPC advises retesting only if signs continue, 24 to 48 hours after finishing treatment, using a stool float rather than an antigen test.^1,6 European guidelines suggest a check test within 3 days of the last dose.⁴ Antigen and PCR tests can stay positive for some time after successful treatment, so a positive result doesn't always mean treatment failed.^1,5

Why Giardia Keeps Coming Back

• Reinfection from cysts on the coat, in the yard or in shared water, which is the most common cause^1,6
• Other dogs at home that carry Giardia without symptoms^1,4
• Missed doses or a course that was too short^9,5
• Drug resistance or a weak immune system, which are less common^1,5
• Another cause of diarrhea, such as worms, coccidia or a food problem. A dog with ongoing diarrhea and no other cause should be retested.⁴

In multi-dog homes, ask your vet whether all the dogs should be tested or treated together.

Frequently Asked Questions

How do you get rid of Giardia in dogs fast?

Use the prescribed medicine for the full course, bathe your dog at the end, pick up feces daily and clean and dry your dog's areas.

What household cleaner kills Giardia?

Quaternary ammonium disinfectants, steam and boiling water work best. Bleach is less reliable.

Are there home remedies for Giardia?

No home remedy has been shown to work, and no over-the-counter medicine is approved. See your vet.

Should healthy dogs that test positive be treated?

Usually not, unless they live with vulnerable people or in a kennel, or carry a human type.

Can my dog go to daycare or the dog park during treatment?

It's best to keep your dog away from other dogs until the diarrhea has stopped and treatment is finished.