Giardia in dogs

Giardia is a parasite that can infect dogs, cats and even people. This condition is called Giardiasis. We may be blissfully unaware of its existence, until a veterinarian informs us our pet has a giardia infection and needs treatment. 

As pet owners it is important to know how Giardia spreads and the symptoms of infection to minimise the effect Giardia has on both your pet, and the wider household. 

What is Giardia?

Giardia is a single celled parasite that lives inside the small intestine of cats and dogs. It's not visible to the naked eye, and needs a microscope to be able to see the tiny structure. 

The Giardia parasite has two main forms during its life cycle. It can be an active trophozoite when it's living in the small intestine and creating symptoms such as diarrhoea and belly pain. 

Or it can be in the cyst form. The cyst is passed in faeces and is responsible for transmission of infection. The bad news is that Giardia cysts are hardy and can survive extended periods in different environments (soil, water etc). 

This can mean that you can treat a current infection, and heal your pet, but if you do not clean the environment thoroughly, they can catch a new infection from eating a cyst that remains in the environment. 

How do pets catch Giardia?

Pets can catch Giardia through unknowingly eating giardia cysts. These cysts have been passed into the environment by other infected animals. 

Common everyday ways that your pet can be infected include:

• Eating or playing in contaminated water such as streams/puddles
• Licking contaminated soil or objects
• Eating contaminated food or material such as grass
• Coming into contact with contaminated faeces

When you look at the list, you see that coming into contact is mentioned. This is because dogs and cats can ingest cysts while grooming themselves. The cysts may have been picked up in the environments described above when playing or rolling for example, and the cysts may become attached to their coats. Dogs and cats spend large amounts of time grooming, and so infection is through ingesting the cysts attached to their coats. 

Some areas are more at high risk than others for risk of infection. For example any areas where lots of animals spend time, like boarding facilities or the local dog park. These areas have a higher concentration of animals, and therefore statistically there is more chance of an infection being spread. 

Being responsible about hygiene, for example cleaning up after your dog on a walk, can help reduce the infection risks to other dogs in the local community. 

Looking for digestive care for your pet?

Enter their details to find the best digestive care product for your pet

Get started

What are the symptoms of Giardia?

The two most commonly affected animals of Giardia infections are dogs and cats. When infected with Giardia, they may show some of the following symptoms”

• Sudden onset  and smelly diarrhoea
• Flatulence (passing gas)
• Weight loss
• Stools with a greenish tinge
• Stools with excess mucus
• Blood in the stool
• Low energy or lack of appetite
• Vomiting

Sometimes the symptoms of Giardia are very obvious, and sometimes it can be a bit more subtle. Often called sub-clinical cases, the symptoms may take a while to present themselves. Signs such as gradual weight loss, or a gradual change in stool consistency from solid formed to smelly loose and watery stools are the most common in subclinical infections. It can take months for an owner to appreciate something is amiss, as the changes are so gradual, it's hard to notice the difference. 

The other consideration is that dogs can harbour Giardia internally and show NO symptoms at all. These dogs are classed as asymptomatic dogs, and are the dogs most likely to pass the infection on to another dog and make them unwell from the infection. If one of your dogs has Giardia, it's worth testing all the dogs in the house to make sure all dogs infected with Giardia have the needed treatment

What makes Giardia infections worse? 

If your pet is very young, say a kitten or puppy, their immune system is not fully developed yet, meaning it's easier for the Giardia to multiply and create sickness. 

Immuno-compromised pets are more likely to pick up Giardia infection. Pets who are undergoing chemotherapy, or have undergone major surgery have weakened immune systems, and are more susceptible to infections such as Giardia, that normally wouldn't cause them an issue. 

Cats who have FeLV (Feline Leukaemia Virus) or FIV (Feline Immunodeficiency Virus) have weakened immune systems, meaning if they come into contact with Giardia, it's very likely they will pick up the infection. Cats with FIV or FeLV should live as indoor cats, not in contact with other cats or dogs to allow them to live a lower risk, longer life.

How is Giardia diagnosed? 

A veterinarian will diagnose Giardia based on clinical signs, and testing of the stools. The cysts can be a little tricky to pick up in standard faecal flotation tests, as they can be shed intermittently (infrequently). Instead your veterinarian will send the samples away to the laboratory to run ELISA Antigen testing or PCR detection (looking for the DNA of Giardia). This type of test is more likely to detect if your pet has Giardiasis. 

As the infection can be challenging to diagnose, your vet will likely ask for a pooled stool sample. This requires you to collect small amounts of stool from your pet across 1-3 days to increase the chances of the antigens being present and detected on testing. 

If your pet does have stool tested positive for Giardia, it's important to test all in contact animals - dogs and cats in the same home, and dogs they may spend a lot of time with to help locate any infected animals and treat them promptly. 

Looking for digestive care for your pet?

Enter their details to find the best digestive care product for your pet

Get started

How is Giardia treated?

There are different ways to treat Giardia, and your veterinarian will assess how unwell your dog is whilst considering treatment options. 

One common treatment is an antiparasiticide called Fenbendazole. This is a successful treatment if given as a course over 3-10 days. Another alternative is an antibiotic called Metronidazole, again administered over a course of 3-10 days. 

It's important to note your veterinarian will discuss side effects and risks, particularly in younger animals, as antibiotics can lead to liver damage. Fenbendazole is a safer option for younger animals. 

Probiotics may be recommended to help promote your pets gut health whilst healing is happening. This is a safe way to support the intestines through the recovery phase after illness. 

Diet is another treatment method used alongside medications and supplements. Your veterinarian will recommend a diet that is highly digestible, low in carbohydrates, and high in soluble fibre.

As Giardia is great at surviving outside an animal's body, simply treating it with medication does not guarantee that your pet will be free from infection in the future. We recommend bathing your pet to remove any possible cysts attached to their fur. Dogs will likely have no issues with this, cats less so. A wet cloth passed over the body of a cat at multiple points in time can help to remove the cysts, just be sure to dispose of the cloth after each use, or wash on a 70 degree hot wash cycle. 

It is also a good idea to clean your pets environment with a disinfectant such as bleach. Hot washing their bedding, coats, pillows will also reduce re-infection risks. 

Removing stools from the garden and hosing the areas down after can reduce the contamination of the area with giardia cysts, so try to pick up stools as soon as they are passed if possible. 

After a period of 4 weeks from diagnosis it is a good idea to submit another stool sample test to be sure that your furry friend is free from Giardiasis infection.

Summary 

Giardia is a tiny little parasite that can make your pet quite unwell, with symptoms such as diarrhoea, flatulence and weight loss. Younger animals, or the elderly and immunocompromised are most at risk of catching Giardia infections. Thankfully this disease is easy to diagnose and treat, with most pets making a full recovery in a short space of time.