Giardia in Dogs: Symptoms, Treatment & Cleaning Tips

Giardia in dogs is one of those words that can make pet parents panic, especially if their dog suddenly develops watery, smelly diarrhoea or keeps getting an upset tummy that just will not settle.

The good news? Giardia is common, treatable and manageable with the right veterinary care and a good clean-up plan at home.

The slightly less fun news? It can be stubborn, cause long lasting gut damage, is messy and easy to spread if you don’t have a good hygiene protocol in place. So, if your dog has been diagnosed with giardia, this is your friendly, no-panic, canine nutritionist, expert guide to what it means, what signs to look for, how it is treated and how to reduce the chance of it bouncing around your home, garden or favourite walking spots.

What is giardia in dogs?

Giardia is a tiny single-celled parasite that can live in the intestines of dogs, humans and other animals. The most common species affecting dogs is often called Giardia duodenalis or Giardia intestinalis.

Dogs become infected when they swallow giardia cysts. These cysts are passed out in the poo of infected animals and can contaminate:

• Puddles

• Streams

• Standing water

• Soil

• Grass

• Food bowls

• Toys

• Bedding

• Floors

• Fur around the back end

• Areas where infected dogs have toileted

This is why dogs who love sniffing, licking, drinking from puddles or exploring areas with lots of other dogs may be at a higher risk.

Once swallowed, the parasite can attach to the lining of the small intestine. This can interfere with digestion and absorption, which is why many dogs develop diarrhoea, mucus, weight loss or general tummy upset.

Is giardia contagious?

Yes, giardia can spread between dogs through faecal contamination. That means infected poo is the main problem.

A dog does not have to directly eat another dog’s poo to become infected. Tiny contaminated particles can be present in the environment, on paws, on fur, in shared water bowls, bedding or in damp outdoor areas.

This is why hygiene is just as important as medication. If the environment is not cleaned properly, dogs can reinfect themselves after treatment very easily.

Can humans catch giardia from dogs?

It is possible, but it is not considered the most common route for human infection. Different strains of giardia can affect different species. However, good hygiene is still essential, especially in households with young children, elderly people, pregnant people or anyone immunocompromised.

Wash your hands thoroughly after picking up poo, cleaning bowls, washing bedding or bathing your dog. Do not let your dog lick faces while they are being treated for giardia, and avoid sharing towels or bedding.

Symptoms of giardia in dogs

Some dogs can carry giardia and show very few signs. Others can become quite unwell, especially puppies, senior dogs, dogs with existing gut problems or dogs with weaker immune systems.

Common symptoms of giardia in dogs include:

• Watery diarrhoea

• Soft, sloppy or poorly formed stools

• Very smelly poo

• Mucus in the stool

• Pale, greasy or fatty-looking stools

• Intermittent diarrhoea that improves and then returns 

• Increased urgency to toilet

• More frequent bowel movements

• Wind or gurgly tummy noises

• Vomiting

• Reduced appetite

• Weight loss

• Poor coat condition

• Lethargy

• Dehydration in more severe cases

One of the tricky things about giardia is that symptoms can come and go and they can present just like an “off tummy”. A dog may seem better for a few days and then suddenly have loose stools again.

This does not always mean the treatment “has not worked”. It may be reinfection, incomplete environmental cleaning, another gut issue alongside giardia or a sensitive digestive system that needs time to settle.

When should you contact your vet?

You should contact your vet if your dog has:

• Diarrhoea lasting more than 2-3 days

• Blood in the stool

• Repeated vomiting

• Signs of dehydration

• Weight loss

• Lethargy

• Loss of appetite

• Vomiting with or without blood

• Diarrhoea in a puppy, senior dog or medically vulnerable dog

• Repeated episodes of loose stools that keep returning

Giardia cannot be diagnosed just by looking at poo. Your vet may recommend a faecal test to check for giardia and other parasites or infections.

This is important because many conditions can look similar, including dietary intolerance, worms, bacterial infections, pancreatitis, inflammatory bowel disease, stress colitis or sudden diet changes.

How is giardia diagnosed?

Your vet will usually ask for a stool sample. Sometimes one sample is enough, but because giardia cysts may not be shed every single time your dog poos, your vet may ask for samples from different bowel movements over a few days.

Testing may include:

• Faecal flotation

• Direct smear

• Giardia antigen testing

• PCR testing in some cases

Your vet will decide which test is most appropriate based on your dog’s symptoms and history.

Treatment for giardia in dogs

Giardia treatment should always be guided by your vet. There are no safe over-the-counter shortcuts that should replace proper veterinary care.

Treatment may include:

1. Prescription medication

Vets commonly use medications such as fenbendazole or metronidazole, depending on the dog, symptoms and local prescribing guidance. Some dogs may need one medication, while others may need a combination or repeat treatment.

Always follow your vet’s instructions carefully and complete the full course, even if your dog’s poo looks better after a couple of days.

2. Supportive care

If your dog has diarrhoea, they may need extra support to prevent dehydration. In mild cases, this might mean encouraging water intake and feeding a suitable gastrointestinal diet advised by your vet.

In more severe cases, your dog may need veterinary treatment such as fluids or additional medication.

3. Diet support

Some dogs benefit from a highly digestible gastrointestinal diet while their gut recovers. This does not mean their usual food caused the giardia. It simply means the digestive system may need an easier job while it is inflamed and irritated.

Avoid suddenly adding lots of new foods, rich toppers or fatty treats when your dog has diarrhoea. Even healthy extras can make loose stools worse if the gut is already upset.

Small, simple, consistent meals are often better than constantly changing foods.

4. Bathing

Your vet may recommend bathing your dog during treatment, especially around the back end, tail, legs and paws. This helps remove cysts that may be stuck to the coat and reduces the risk of your dog reinfecting themselves and other dogs.

Use a dog-safe shampoo and dry your dog thoroughly afterwards.

Why cleaning matters so much

Medication treats the dog, but cleaning helps manage the environment.

Giardia cysts are passed in poo and can survive in damp environments. If stools are not picked up quickly, your dog may be exposed again in the garden, on walks or through contaminated bedding and fur.

This is why the most successful giardia plans usually include both veterinary treatment and a serious hygiene routine.

It is not glamorous, but it is effective.

How to manage giardia at home

Here are practical steps to help reduce the chance of reinfection.

1. Pick up poo immediately

This is the big one.

Pick up every stool as soon as possible, whether your dog toilets in the garden, on a walk or in a shared outdoor space.

Do not leave stools sitting in the garden “for later”. Giardia cysts can contaminate the area and increase the risk of reinfection.

Use poo bags, tie them securely and dispose of them safely.

2. Pick up poo in public places

This matters for your own dog, other dogs and the wider community.

If a dog with giardia poos in a park, on a pavement, near a walking trail or in a shared green space and it is not picked up, other dogs may be exposed.

Even if your dog is not currently showing symptoms, picking up poo is one of the simplest ways to reduce parasite spread.

Public poo picking is not just good manners. It is disease prevention.

3. Clean the garden toileting area

If your dog has been toileting in the same part of the garden, remove all faeces promptly.

For hard surfaces such as patios, concrete or paving, clean the area thoroughly with disinfectant and hot water and allow it to dry. 

For lawns, remove stools immediately and try to keep the area as dry as possible but also pour boiling water over the area. Giardia likes damp environments, so avoiding soggy, contaminated patches can help.

4. Wash bedding daily during treatment

Wash your dog’s bedding, blankets and soft toys regularly while they are being treated.

Use a hot wash where the fabric allows, and dry thoroughly. Damp bedding is not your friend here.

If your dog sleeps on your sofa or bed, wash throws, covers and any shared blankets too.

5. Clean bowls and toys

Food bowls, water bowls and washable toys should be cleaned  1-2 times daily during treatment.

Use hot soapy water, rinse well and dry thoroughly. If your dog has shared bowls with other dogs, clean those too and consider separating bowls until the infection has resolved.

6. Bathe your dog

A bath can help remove cysts from the coat, especially if your dog has had diarrhoea or has long fur around their back end.

Pay particular attention to:

• Paws

• Back legs

• Tail

• Bottom area

• Belly fur

For longer-coated dogs, keeping the hair around the back end trimmed can make hygiene easier while they recover.

7. Keep your dog away from puddles and stagnant water

Dogs can pick up giardia from contaminated water, so try to stop your dog drinking from:

• Puddles

• Ditches

• Streams

• Ponds

• Shared outdoor bowls

• Standing water in parks

Bring fresh water on walks if your dog tends to drink anything they find.

8. Avoid doggy daycare or busy dog parks during active infection

While your dog is being treated and still having diarrhoea, avoid high-dog-traffic environments where they could spread infection or pick it up again.

This includes:

• Doggy daycare

• Boarding kennels

• Busy dog parks

• Shared training classes

• Group walks

Ask your vet when it is safe to return.

What about other dogs in the house?

If you have more than one dog, speak to your vet. They may recommend testing or treating other dogs depending on symptoms, exposure and risk.

You should also clean shared bedding, bowls, toys and toileting areas.

Try to stop dogs from grooming each other’s back ends or sharing water or food bowls while treatment is ongoing.

Should you use probiotics?

Some dogs may benefit from gut support after diarrhoea, but probiotics are not a replacement for veterinary treatment.

If you want to use a probiotic, choose one with evidence behind it and ask your vet which product is suitable for your dog. Avoid throwing lots of supplements at the problem at once, as this can make it harder to know what is helping and what is upsetting the gut.

Can treats be given during giardia?

Yes, but keep it simple and I would probably advise not to feed anything but their food whilst on treatment.

When a dog has diarrhoea, the digestive system is already irritated. Rich, fatty or heavily processed treats may worsen loose stools.

Choose light, simple treats and keep them within your dog’s daily calorie allowance. Treats should complement the diet, not replace proper nutrition or veterinary care.

If your dog is on a veterinary gastrointestinal diet, ask your vet whether treats are suitable during the treatment period.

How long does giardia last?

Many dogs improve with appropriate veterinary treatment, but recovery time can vary.

Some dogs improve quickly, while others may have lingering soft stools as the gut settles. If signs continue, your vet may recommend repeat testing, a longer treatment plan or investigation for other causes of diarrhoea.

Giardia can irritate the lining of the small intestine, which may temporarily affect digestion, nutrient absorption and stool quality. This is one reason some dogs continue to have soft stools, mucus, gurgly tummies or intermittent digestive flare-ups even after the parasite itself has been treated.

In some cases, especially where a dog has had repeated infection, severe diarrhoea, underlying gut sensitivity or a history of digestive disease, the intestinal barrier and microbiome may need longer to recover. This does not necessarily mean there is permanent damage, but it can mean the gut remains more reactive for a while. During this period, constantly changing foods, adding rich toppers or using high-fat treats can make symptoms worse.

This is where a veterinary gastrointestinal diet can be really helpful. GI diets are usually designed to be highly digestible, controlled in fat, gentle on the gut and supportive of stool qualityYour vet may recommend staying on a gastrointestinal diet for around 8–12 weeks, or longer in more sensitive dogs, depending on symptoms and recovery.

Once stools are consistently normal, your vet or canine nutrition professional can help you transition slowly back to a suitable complete and balanced diet. The key is not to rush the gut just because the medication has finished. Recovery is not only about killing the parasite — it is also about helping the digestive system rebuild confidence.

How to reduce the risk of giardia coming back

You cannot bubble-wrap your dog from every parasite, but you can reduce risk.

Useful prevention steps include:

• Pick up poo immediately

• Avoid letting your dog drink from puddles or stagnant water

• Wash bedding regularly

• Clean bowls and toys

• Keep your dog’s back end clean

• Avoid heavily contaminated walking areas

• Practise good hand hygiene

• Keep puppies away from unknown dog poo

• Use faecal testing when your vet recommends it

And yes, always pick up poo in public. It protects your dog, other dogs and the people who share those spaces.

Final thoughts

Giardia in dogs is not pleasant, but it is manageable.

The key steps are:

1. Speak to your vet

2. Test rather than guess

3. Use prescribed treatment properly

4. Pick up poo immediately

5. Wash bedding, bowls and toys

6. Keep your dog clean and dry

7. Prevent access to contaminated water

8. Avoid spreading it in public places

With the right treatment and hygiene plan, most dogs recover well. And while giardia may be tiny, your cleaning routine can make a huge difference.

References and further reading

• CDC: About Giardia and Pets

• CDC: Giardia Infection Prevention and Control

• CDC: Cleaning and Disinfecting Pet Supplies

• Cornell Riney Canine Health Center: Giardia Infection, Treatment and Prevention

• Merck Veterinary Manual: Giardiasis in Animals

• Companion Animal Parasite Council: Giardia Guidelines