Giardia in Dogs

When it comes to Giardia in the kennel, the concern is less about treatment and more about the long-term plan to manage it. Giardia is one of those parasites that always seem to be waiting for the perfect time to strike. In a kennel, this time is usually after weaning and right around the time the puppies get to their new home - both inconvenient times for a breeder.


Giardia is a tiny, one-celled parasite that lives in the intestine of affected animals. It is difficult to diagnose and can affect both cats and dogs. Not all animals with the infection show clinical signs. Symptoms are more visible in younger and older animals. The first clinical sign of Giardia is usually diarrhea with a strong odor or excessive mucus. Dehydration may also occur due to the diarrhea.


Giardia can be difficult to see under a microscope, and it often takes a trained eye to identify them accurately. Screening tests are also available. In these tests, the feces is mixed with a solution, placed in a well and then "snapped" down to start the test, which checks for a protein from the Giardia organism. Snap tests are useful as a piece of the puzzle; they are not a definitive test. Though negative tests are true negatives, false positives are very common and may be deceiving. If you have a positive snap test and you're not sure if it's correct, send feces to the lab for more accurate diagnosis. Since a snap test can read positive for 3 weeks after Giardia is removed from the gut, don’t be too quick to call the treatment a failure!


Metronidazole has traditionally been used to treat Giardia, but lately there has been resistance (60% effective). The current treatment of choice is Fenbendazole (Safeguard®) which is 96% effective when used 6 days in a row.

Bathing is also important. Giardia oocysts are sticky and will stay on the hair coat, particularly the back legs. The oocysts are directly infective. This means when the dog passes them in the stool, they can immediately re-infect the animal while he grooms. Bathe the dog with Chlor 4 Shampoo on days 3 and 5 of treatment. The chlorhexidine will kill the oocysts. Concentrate on the back half of the body, as this is where the Giardia usually sticks. If you don’t bathe them, they can just re-infect themselves, making your treatment ineffective.

Since Giardia is stubborn, contaminated kennels should be scrubbed and disinfected. Chlorhexidine disinfectant is effective against the spores at room temp and quaternary ammonia is effective at both room temp and colder. Caution: Quaternary ammonia is not safe around nursing babies - fading puppy/kitten syndrome!


Long-term control starts with the mother. When she is heavily pregnant, the stress will decrease her resistance to parasites. Using Fenbendazole three days in a row after day 50 of gestation is helpful in preventing the transfer of parasites, including Giardia to babies. Use Fenbendazole 6 days with problem moms who have had previous Giardia litter issues!

Bathing the mother before whelping is also helpful when fighting the problem. Alternatively, some breeders will clip the hair on the back legs and belly to remove the oocysts the mom carries on her hair. Either technique is effective. The goal is preventing transfer to babies!

For puppies, deworm three days in a row with Safeguard® at 6 and 8 weeks of age for prevention. The 6 week prevention is crucial because this is the age Giardia sets up in the intestine with most Giardia diarrhea starting at 8-10 weeks. This way you eliminate any Giardia that have found their way into the baby before you have to deal with diarrhea.


The problem with routine Giardia prevention is we kill the susceptible Giardia, leaving any resistant Giardia to reproduce. If dealing with resistance, traditional Giardia treatment has to be altered for a time. The resistant Giardia needs to be eliminated, if possible, to avoid spreading.

If resistant Giardia is an issue, your veterinarian may prescribe Secnidazole – most Giardia issues clear with one dose. Ronidazole has also been shown to be effective against resistant Giardia in dogs. In addition to the drug treatment, bathing the dog with a shampoo containing chlorhexidine (Chlor 4 Shampoo) is important for the efficacy of the treatment.


With all parasites, you want to think long-term control. If you just treat the babies without considering where the parasite is coming from, you'll eventually get resistance that overwhelms your medication. Every year you should have fewer and fewer parasite numbers in your kennel. Roundworms, hookworms, whipworms, Coccidia and Giardia should all be accounted for in your preventative program. If babies don’t get Giardia, you don’t have to get them back out! If you have any questions about parasite control, feel free to give us a call!

If you need help, call us at 1-800-786-4751.

-Dr. B
Don Bramlage, DVM, Director of Veterinary Services at Revival Animal Health

The materials, information and answers provided through this website are not intended to replace the medical advice or services of a qualified veterinarian or other pet health care professional. Consult your own veterinarian for answers to specific medical questions, including diagnosis, treatment, therapy or medical attention.

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