Giardia In Dogs


Giardiasis is an unpleasant parasitic infection  that can affect  humans too. If your dog or puppy has been suffering from bouts of diarrhoea for some time,  the Giardia parasite is a possibility that your vet will want to consider. People often worry that the treatment for Giardia in dogs is making the diarrhoea worse,  but an increase in diarrhoea is likely to occur at random times during the illness making it difficult to pin-point the cause.

It is important to inform your vet if your dog’s condition is  worsening, but you may be advised to persist with the treatment.

What is Giardia?

Giardia is a single celled parasitic organism that lives in the intestine of other animals. It has two forms,  one of these forms is active and mobile,  the other is a ‘spore’  or hard walled form.

Giardia is an unpleasant 'bug' that can make dogs and people sick. We answer your giardia questions here. These ‘spores’ or ‘cysts’ can survive for long periods of time (months) in cold stagnant water, so this is the most likely source for most dogs to pick it up from.

How do dogs catch Giardia?

Giardia is spread when an animal accidentally eats giardia cysts. Most dogs have contact with other dogs, even if it’s just out on a daily walk. Victims of Giardia are usually infected by contaminated water, but it can be passed through food, contact with faeces or grooming. Giardia is a big problem for some pounds, where the parasite can speed through the kennels at an alarming rate. The close proximity of the dogs means that they are more likely to pass any contractable condition around in short order.

Symptoms of Giardia in dogs

Some dogs with Giardia will be symptomless.  They just carry the illness and pass it to other dogs. Other dogs will be very poorly with bouts of  very smelly and profuse diahorrea that fails to respond to normal measures.

In puppies, Giardia can be very serious indeed. The symptoms will often be more severe than in adult dogs. Here are some of the main warning signs to look out for in your dog. He may show one or many of the following symptoms:

  • Watery faeces
  • Frothy faeces
  • Mucus in faeces
  • Green colouration to faeces
  • Very smelly faeces
  • Blood in faeces
  • Vomiting
  • Weight loss

Not only will the potential signs of Giardia vary from dog to dog, they may also vary for that individual at different times. Symptoms can be continuous, but they can also appear and disappear quite suddenly.


It is important to be aware that the symptoms temporarily leaving does not necessarily indicate that the underlying condition has gone. Although giardia is not usually fatal, it can be. Especially in young pups with immature immune systems, or in adult dogs whose immume systems are compromised for an unrelated reason.

Diagnosing Giardia

Diagnosing Giardia is a job for your vet.  Any dog with persistent diarrhea should be examined by a veterinary surgeon and there are many possible causes of symptoms which may resemble those of Giardia. Diagnosis of Giardia can be problematical and false negative results are common.

To confirm the diagnosis, your veterinarian will  send a sample of your dog’s faeces to a laboratory. There it will be examined under a microscope for tell-tale spores. However, false negatives can occur because the parasite does not shed spores all the time,  they will therefore only be present in the faeces intermittently. For this reason, your vet may therefore advise you to treat the dog anyway.

It is however also possible for you to get a false positive diagnosis for Giardia too! As the cysts which identify the parasite can look quite similar to yeast. However, this is less of a concern as it is better to treat your dog for giardia mistakenly than to potentially leave it with a parasitic condition.

Treatment for dogs with Giardia

The drugs commonly used for treating Giardia in dogs are fenbendazole and metronidazole. Most vets seem to pick fenbendazole first, and the standard course of treatment is five days. Fenbendazole is the key ingredient of a well known wormer sold under the trade name Panacur.

Metronidazole is an alternative option, although it has more downsides. For example it is not suitable for pregnant dogs. In addition to this, the Companion Animal Parasite Council also state that metronidazole has been reported to have as low a treatment rate as 50%. Metronidazole may be sold as Flagyl and is prescription only, but Panacur can be bought over the counter or online.

veterinary giving the vaccine to the ivory labrador dog in clinic

Some pups will need to be kept at the veterinarian’s if for example his fluid levels have become too low and he requires a drip. However, provided your dog is not too seriously unwell, he will be able to stay at home whilst receiving his treatment. Most dogs are able to be treated on an outpatient basis.

Avoiding transmitting giardia to humans

Although it is unusual for people to catch Giardia from dogs, it does happen. So if your dog has Giardia you must be scrupulously careful over hygiene. Get some hibiscrub and give your hands a good ‘going over’ after clearing up and disposing of faeces. It is however far more common for humans to catch giardia from other humans than from their infected pets. Pet to pet infection is much more likely.

Avoiding transmitting giardia to other dogs

If you have other dogs in your family, your vet may advise you treat them all at the same time. There are other precautions that you should take whilst your dog is infected to try and ensure that the parasite is not spread.

Make sure that your dog is thoroughly bathed with shampoo, to remove any trace of faeces and the parasitic spores from their coats. Wash all of your dogs at the same time, to avoid re-introduction of the parasites from their housemates’ coats.

Avoid going for walks in public places whilst treatment is being carried out, for the benefit of the other animals you might meet while you are there. Remember, dogs love to sniff at each other but they also interact with the mess they leave behind! So even walking at unsociable hours could result later on in the day in another dog picking up stray spores and becoming unwell. For advice on alternative ways to exercise your dog without going for a walk take a look at this article. Remember to avoid the options involving other people’s dogs, to ensure that you don’t accidentally pass the parasite on!

Contacting your vet

If you are concerned that your dog might have contracted giardia, then contact your vet immediately. It is important to get any dog with persistent diarrhoea to a vet. With small puppies severe diarrhoea is an emergency so do not delay. With proper treatment almost all dogs make a full recovery from this unpleasant illness. If you have kennels on your property you may find it interesting to read Vet Maggie Fisher’s online article  on dealing with Giardia outbreaks.

Has your dog ever suffered with giardia? Why not let us know about your experience in the comments section below.

More information on puppies

For a complete guide to raising a healthy and happy puppy don’t miss The Happy Puppy Handbook.

(paid link)Published in April 2014, the Happy Puppy Handbook covers every aspect of life with a small puppy.

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This article has been fully revised and updated for 2015.

References and Resources

The Labrador Site Founder

Pippa Mattinson is the best selling author of The Happy Puppy Handbook, the Labrador Handbook, Choosing The Perfect Puppy, and Total Recall.

She is also the founder of the Gundog Trust and the Dogsnet Online Training Program 

Pippa's online training courses were launched in 2019 and you can find the latest course dates on the Dogsnet website


  1. My black labrador tested positive for Giardia, then treated with Panacur granules, seemed to clear up but now i fear is sick with Giardia. A recent stool test came negative, but i don’t believe it because he is back with the same symptoms again, bouts of firm but runny stools mostly at night, sometimes 2 times at night (11:30 pm & 3:30 am) or just once at night. Daytime is normal stool movement. Question is Cocoanut Oil good to get rid of the parasite. I’m calling my vet to let her know what is happening with my dog. But in the mean time is cocoanut oil good to get rid of the parasite when all the meds are taken?

  2. My lab puppy is 18 weeks now. She had a problem with poos from the day we brought her home. Vet confirmed giardia. She has been three four doses of panacor but is still positive i have been super clean etc but still she tests positive. What else can i do? I ve tried pumpkin and pectin etc but not that helpful. Any suggestions please please

  3. When our puppy was 8 Weeks old she was diagnosed with Giarda. She was treated for 5 days with Panacur and retested in two weeks for the Giarda. That test came back positive and she was then treated with Panacur and flagyl for 10 days and retested 3 weeks later. That test came back positive as well. So this time we added pumpkin to our puppies diet plus probiotics and put her back on Panacur for 7 days. Finally at 4 months of age she was free of giardia. I would clean her toys, food bowls, crate and the floors with bleach every day. We would wash our hands every time we came in contact with the puppies stool or mouth. We bathed the puppy before and after each treatment and picked up her stool from the yard every time she went. It was a lot of work but she is fine now and at 8 months she weighs 74 pounds.

  4. I have a Biewer yorkie and my daughter has her sister, we got them in Dec 2016 poppy poop was soft when I had her but in January she had diarrhoea she had a week antibiotics while we waited for poo results she had giardia had 10 days panacur when 3 days still had it then 3 weeks antibiotics and panacur together now waiting for poo test but today poo was now right again do not known what to do she is 6 months now and have had it since I had her and and her sister ellie

  5. If left untreated you will pass this awful condition on, it is a moral responsibility to treat. our dog contracted this due to other peoples ignorance and has taught me a great deal about the condition, weight is the tell tale sign, but then rising much later in the morning, jelly coating the poo, general slower dog, need to go out suddenly, and frantic searching when out walking to find a decent poo spot. runny poo does not always happen, only when the condition becomes quite serious does diarrhea begin to set in. If you love your animal, and yourself you would not let them carry this to spread and feel bad. If anything, carrying this persistently will shorten your dogs life. There is little known about giardia lamblis which is why vets want to follow up and see whether treatment was a success, ours was one big treatment, then six more days of another treatment. it took him a log long time to put weight on again.
    wash their toys as well as bedding and keep the edges and sides of feed bowls and water bowls cleaner than usual. wipe their bums for at least a week after treatment has ended as well as during.
    but my biggest suggestion…do not worm your dog regularly unless you suspect or have tested them for worms. the drug used is making dogs that are unable to fight this disease with medicine, they are almost becoming immune like humans with anti biotics. over use is no good thing, better to have a twice or three times a year fecal test, non invasive and cheaper, and it makes sense to test regular, even if you worm regular, there is no sure way to know you have wormed correctly.

  6. We have a 12 week Labrador puppy “Patrick” who has giradia. He started medication yesterday which will run for 5 days. He continues to want to chew everything from twigs to gravel and shoes, does this put him at risk of re-infection?

  7. We have a 3 month old Golden pup that was just diagnosed with giardia from a stool sample we provided. She has no symptoms what-so-ever but the vet has suggested treatment starting immediately. We start today.

  8. Why treat our 4 mos old lab puppy for Giardia when it is so common in the environment and she will be with me outside in rivers etc. all the time anyway?