If your dog is struggling with watery diarrhea, one of the possible causes is Giardia. This is one of the most common intestinal parasites in dogs, and while Giardiasis is rarely life-threatening in healthy adult dogs, it can be uncomfortable, contagious, and worth treating promptly. In puppies, however, Giardiasis can be life-threatening and may need urgent vet care.
This Sploot Vets guide covers everything you need to know about Giardia in dogs, the symptoms to look out for, how it’s diagnosed, and how long infections can last.
I. What is Giardia in Dogs?
Giardia is the term for microscopic, single-celled, protozoan parasites belonging to the genus Giardia. In veterinary medicine, most infections are caused by ‘Giardia duodenalis’ (also called ‘Giardia intestinalis’). Once contracted, G. duodenalis attaches to the dog’s intestinal lining, leading to disrupted nutrient absorption and various Giardia symptoms in dogs that primarily impact the digestive system.
While dogs of any age can get Giardia, puppies and younger dogs are more susceptible to it due to their developing immune system. Senior dogs and dogs with compromised immune systems can also develop Giardiasis if exposed to the parasite.
Note: In medical terms, ‘Giardia’ refers to the parasite or pathogen, while ‘Giardiasis in dogs’ refers to the illness or infection. However, ‘Giardiasis’ is commonly shortened; therefore, ‘Giardia’ can mean both the parasite and the resulting illness.
a. How Does a Dog Get Giardia?
Dogs get Giardia through the fecal-oral route as they ingest infected cysts. Giardia cysts can survive in the environment for weeks to months, especially in moist conditions. Common sources of Giardia in dogs include:
- Drinking from contaminated water (e.g., puddles, ponds, lakes)
- Ingesting or licking contaminated soil or stool
- Licking their paws after stepping on contaminated soil or stool
- Playing with contaminated toys or sharing in communal water bowls.
b. What are Giardia Cysts?
There are two main forms of Giardia: the infectious cyst and the trophozoite. The infectious Giardia cyst is shed in feces, and trophozoites are the active, feeding form that colonize the small intestine and cause disease.
To fully illustrate the lifecycle of Giardia in dogs, here are the main stages:
- Exycstation – the Giardia cysts are ingested by the dog. Each cyst releases two Giardia trophozoites in the intestines.
- Proliferation – Giardia trophozoites attach to the intestinal lining, feed from dissolved nutrients, and reproduce rapidly through binary fission. (A single surviving trophozoite can still establish a colony if not overcome by the dog’s gut immunity.)
- Encystation – While some trophozoites can stay and continue to cause disease, some will turn into infectious cysts as they move towards the large intestines and are then shed in the dog’s stool. In dogs, it can take 5 to 12 days after infection for cysts to appear in their stool.
II. Giardia Symptoms in Dogs
Not every infected dog shows symptoms, but when they do, the clinical signs of Giardia in dogs typically include:
a. Primary Symptoms of Giardia in Dogs
- Soft, watery, or greasy diarrhea in dogs (sometimes with mucus)
- Sudden or recurring loose stool
- Excess gas or bloating
Note: There are many causes of diarrhea in dogs, but diarrhea caused by Giardia often has certain characteristics, such as a pale, greasy, or foul-smelling quality. If you're seeing any of these signs, schedule a vet visit promptly.
b. Other Possible Giardia Symptoms in Dogs
- Vomiting in dogs
- Weight loss or failure to gain weight
- Low energy or lethargy
- Decreased appetite in dogs
Note: The above symptoms of Giardia in dogs typically present when the infection is severe or chronic. These are also more common in infected puppies, immunocompromised dogs, and senior dogs.
c. Is Giardia in Dogs Serious? When is It Urgent?
For most healthy adult dogs, Giardia is not life-threatening, but it can lead to weight loss and other complications over time. However, in puppies, seniors, and dogs with underlying health issues, dehydration and other complications can become serious more quickly.
If you notice the following symptoms, contact an urgent care or emergency vet:
- Signs of dehydration (dry gums, sunken eyes, lethargy, skin that doesn't snap back when gently pinched)
- Vomiting alongside diarrhea for more than 12–24 hours
- Extreme fatigue or weakness
d. How Long Does Giardia Last in Dogs?
With treatment, most Giardia symptoms improve within 5–7 days. Complete resolution, confirmed by a clear follow-up fecal test, typically takes 2–4 weeks. However, without treatment, Giardia infections can persist for weeks to months and may cause ongoing weight loss, chronic diarrhea, and nutritional deficiencies.
→ If you notice any of the above urgent symptoms, we recommend seeking urgent veterinary care. Call us at (720)770-8656 to schedule a same-day urgent care appointment. To schedule a regular vet visit at Sploot, book your appointment here. Our vet clinics in Denver, Chicago, Colorado Springs, and Salt Lake City are open 7 days a week.
III. How Vets Diagnose Giardia in Dogs
Early diagnosis of Giardia in dogs is the first step to prompt treatment, which is important to prevent ongoing intestinal distress, reduce transmission, and stop chronic infection cycles.
Like many canine diseases, Giardiasis can't be diagnosed by symptoms alone. Various conditions cause similar GI symptoms, including worms in dogs, dog food allergies, bacterial infections, and other dietary issues. A fecal test is required to confirm the diagnosis.
a. Fecal Testing: Direct Smear and Flotation for Giardia
A direct fecal smear involves examining a fresh stool sample under a microscope to look for Giardia cysts. Fecal flotation uses a solution that makes parasite cysts float to the top of the sample for easier detection.
These are standard in-clinic tests and are often the first line of veterinary diagnosis. Because Giardia cysts aren't shed continuously, a single negative test doesn't always rule out infection. Your veterinarian may recommend running multiple samples if symptoms persist.
b. Giardia Antigen Testing for Dogs
Giardia antigen testing detects specific Giardia proteins in the stool using an ELISA (enzyme-linked immunosorbent assay) method. It's generally more sensitive than traditional microscopy and can be used alongside flotation testing for a more complete picture.
Note. At Sploot, in-house veterinary diagnostics mean that our veterinarians can collect the sample and run the tests during the same vet visit.
IV. How We Treat Giardia in Dogs
Giardia in dogs is fully treatable. Most dogs respond well to medication and recover fully with proper care. At Sploot Vets, we take the following steps to ensure your dog is on the path to being at their healthiest and happiest:
a. Stabilizing Your Dog’s Condition
When you arrive at our vet clinic, our veterinary team may focus on first stabilizing your dog’s condition. Your dog will get a preliminary physical exam, and the veterinarian may request lab work or diagnostics. The vet will also manage any possible dehydration or electrolyte imbalances due to chronic diarrhea and vomiting.
b. Giardia Medicine for Dogs
Once Giardiasis is diagnosed, our veterinarian will prescribe medications to treat the infection. The two most commonly prescribed medications for Giardia in dogs include the following:
- Fenbendazole (Panacur) – An antiparasitic typically given for a prescribed number of days. It's generally well-tolerated and often the first-line treatment.
- Metronidazole (Flagyl) – An antibiotic with antiparasitic properties, sometimes used alone or in combination with other medications.
c. Nutritional Support for Giardia in Dogs
At Sploot Vets, we don’t just prescribe medications; we also provide personalized treatment plans to give your dog the best chance of recovery. For cases of Giardia in dogs, our team may also prescribe nutritional support in the form of:
- A bland diet or dog food for sensitive stomachs – this can help reduce intestinal strain and irritation while your dog is getting treated for Giardia.
- Probiotic chews for dogs – these can help restore healthy gut bacteria and improve intestinal balance, which can lead to a faster recovery from canine Giardiasis.
d. Bathing & Disinfecting
Giardia cysts can cling to the fur and increase the chances of reinfection. Therefore, our veterinarian may recommend bathing your dog during and/or at the end of the treatment.
Since cysts can also survive on surfaces, veterinarians may also recommend cleaning your dog’s food/water bowls, crate, toys, and bed with household disinfectants. As for surfaces that are harder to clean (e.g., couch, carpets, heavy rugs), steam cleaning can be used to help eliminate any lingering Giardia cysts.
Note: With a thorough treatment plan and disinfection, it is possible to clear your dog’s Giardia infection sooner and with just one or a few rounds of Giardia medicine for dogs.
e. Follow-Up Vet Visit
A follow-up vet visit may be scheduled at least 2 weeks after treatment to confirm that the infection has cleared. This timing accounts for the timeframe it takes for Giardia cysts to appear in the dog’s stool after infection or re-infection.
→ If your dog is showing GI symptoms, we’re here to help. Sploot offers same-day vet visits and in-house veterinary diagnostics to provide your dog next-level care. Book a same-day visit today. We're open 7 days a week, with vet clinics in Denver, Chicago, Colorado Springs, and Salt Lake City.
V. Prevention Tips for Canine Giardiasis
Here are some helpful tips to reduce your dog’s exposure to Giardia cysts:
- Always bring your own water for your dog on walks and hikes. Don't let them drink from puddles, streams, or communal bowls at dog parks.
- As much as possible, AVOID sharing your dog’s food bowl or toys with other dogs.
- Pick up your dog’s poop promptly, whether it’s in your yard or in a shared space.
- After your dog spends time in shared spaces, consider giving them a rinse-down and cleaning their paws.
- As part of dog swimming safety practices, give them a rinse before taking them back to the car. Then, bathe your dog either at home or at a self-service dog wash.
- Schedule a regular wellness exam for your dog – routine fecal testing can detect Giardiasis sooner, sometimes before noticeable symptoms develop.
→ SplootPack™ members receive three wellness exams per year at Sploot Veterinary Care, making it easy to stay on top of preventive care year-round.
VI. Safety Tips for Pet Parents & Giardia Seasonality
Giardia in dogs can be zoonotic—meaning dog-to-human transmission can happen (though not very common). It is also important to note that Giardia can infect dogs all-year-round, with different risk factors for each season.
Can Dogs Get Giardia During Colder Months?
Yes. Giardia thrives best in moist, cool environments. During the colder months, cysts generally survive longer on contaminated soil and surfaces. Additionally, over the holidays, more pet parents may consider dog boarding services. If the pet boarding establishment does NOT have consistent sanitation practices or a watchful staff during group playtime, dogs are at risk of direct contact with contaminated stool or surfaces.
Can Dogs Get Giardia During Warmer Months?
Yes. While Giardia thrives in cooler temperatures, warmer temperatures do NOT remove or significantly reduce the risk of Giardia. To kill 99 percent of Giardia cysts, the temperature must be greater than or equal to 56°C—a temperature range that even the hottest days of summer don’t typically reach.
Additionally, the increased time outdoors and in shared spaces during warmer months can increase the risk of exposure to Giardia cysts. Similarly, when dogs swim during summer, whether in pools, ponds, or creeks during summer, this can sometimes expose them to Giardia.
Can You Get Giardia from Your Dog?
The short answer: yes, it's possible. When it comes to Giardia in dogs, the causal pathogen can belong to assemblages (genetic groups) A, C, or D.
From these possible assemblages, G. duodenalis assemblage A, though not the most common in dogs, is capable of infecting humans (and cats). Therefore, Giardiasis in dogs is considered a potentially zoonotic disease. The route of dog-to-human infection is fecal-oral contact. This can occur when a person touches contaminated feces and then touches their face or food without washing their hands.
If your dog is diagnosed with Giardia, take the following steps to help prevent the spread:
- Wash your hands after handling your dog or cleaning up waste.
- Pick up feces immediately in the yard and on walks.
- Limit your dog's access to shared water sources or swimming spots.
- Keep infected dogs away from young children, the elderly, and immunocompromised individuals.
Sploot Vets: Same-Day Vet Care for Giardia in Dogs
If your dog has loose stool, mucus in their stool, has frequent diarrhea, or just isn't acting like themselves, we’re here to help!
Sploot Veterinary Care offers all-in-one vet care, available 365 days a year. Get compassionate, next-level care for your dog from one of our vet clinics in Denver, Colorado Springs, Chicago, and Salt Lake City!
Book your appointment online or through the Sploot Vets app! You can also call us at (720) 770-8656 for urgent concerns.
