Common infectious causes of diarrhoea in dogs and puppies

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There are many infectious causes of diarrhoea in dogs and puppies, and this is sometimes associated with other symptoms such as vomiting, lethargy and loss of appetite. A common step in the diagnosis of the cause of diarrhoea is analysis of a pooled stool sample. When collecting a stool sample from your dog it is important to try and collect three samples from three consecutive days to increase the chance of detecting an infection. Once the stool sample has been analysed by the lab, results may indicate a gut infection. In this article we will discuss some of the main gut infections in dogs, and what it means if your dog tests positive.

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The main infectious causes for diarrhoea in dogs are:







Campylobacter infection

Campylobacter species are a group of bacteria that can cause vomiting and diarrhoea in many types of animals, including people and dogs. Humans usually become infected via contact with raw poultry either by improper hygiene when cooking or eating undercooked meat, whilst dogs usually become infected by contact with contaminated faeces, water or food such as raw diets. There are many types of campylobacter organisms, some of which are found in normal dog faeces, and therefore the presence of campylobacter does not always indicate that this bacteria is the cause of your dog’s symptoms. You must be led by your vet, in deciding whether to treat this bacteria if it is found in a stool sample. It is also very important to maintain good hygiene if your dog has tested positive, to prevent infection passing to you or members of your household.

Parvovirus infection

Parvovirus causes a severe life threatening infection in dogs, with the main symptoms being vomiting, diarrhoea and lethargy. In the UK, dogs and puppies can be vaccinated against parvovirus as part of any routine vaccination protocol offered by your vet practice. It is unvaccinated dogs and puppies that are at risk of parvovirus infection. Parvovirus is diagnosed by detecting the presence of virus particles in your dog’s faeces. These particles will only be found if your dog has the infection, or if your dog has been recently vaccinated. Therefore, it is a fairly reliable way to diagnose an infection in dogs with symptoms consistent with parvovirus. There is no specific treatment, but patients often require supportive care, such as intravenous fluids to increase their chance of survival.

Giardia infection

Giardia is a small parasite that causes profuse watery diarrhoea in dogs, cats, humans and many other species. It is contracted by contact with infected faeces or contaminated ground. Symptoms include foul smelling watery diarrhoea, smelly gas, signs of general illness such as lethargy and decreased appetite, weight loss and vomiting. Treatment with a course of Panacur (fenbendazole) for several days is generally successful, though sometimes more than one course is required.

Cryptosporidium infection

Cryptosporidium is a small parasite that can cause watery diarrhoea in dogs, cats, humans and cattle. Transmission is via ingestion of infected faeces, water or food, and some life stages of the parasite can persist in the environment for many days. There are different species of cryptosporidium, one of which is often found in the faeces of cattle, therefore areas around farms have a higher risk of environmental contamination and infection.

Usually the infection will cause diarrhoea that will settle after a few days. However, sometimes the diarrhoea can be more severe, with animals needing hospital treatment, particularly if they are old, young or immunocompromised, for example if they are receiving steroid treatment for another condition. Treatment, if required, is usually with a course of an antibiotic such as tylosin.

Salmonella infection

Salmonella are a group of bacteria, of which a small number are extremely dangerous to humans, and therefore considered a major public health risk. They can cause vomiting and diarrhoea, and also acute septicaemia (typhoid), which kills humans in the UK every year. Dogs and cats usually contract salmonella by eating raw or out-of-date meat, or infected faeces. In dogs and cats, illness from salmonella is rare, but when it does occur it is often serious requiring hospitalisation and antibiotics. However, they can also carry salmonella species, without showing any symptoms, which can then lead to infection in humans of the same household, though this is rare.

Clostridium perfringens type A infection

Clostridium perfringens type A are a type of bacteria very commonly found in the gut of normal healthy dogs (around 80% of the UK dog population!) and rarely cause a problem. There are different strains, some of which produce toxins that target the gut (enterotoxin) and cause bloody diarrhoea, often with mucus. The bacteria produce these toxins in response to certain triggers, such as antibiotic treatment, sudden dietary changes or infection with another bug. Diarrhoea can range from mild to life-threatening, sometimes requiring treatment with antibiotics or other measures such as intravenous fluids. Proving that this bacteria is responsible for your dog’s diarrhoea is difficult: there are tests to establish whether your dog has the toxin-producing strain, and also tests to detect the toxin itself. A heavy growth of the toxin-producing bacteria, presence of the toxin and suspicious symptoms are usually sufficient to start treatment with antibiotics. However, in practice it is rare to use these diagnostic tests, as usually the patient has recovered by the time results are back from the laboratory.

Can I get a stomach bug from my pet?

It is very rare to contract an illness from your dog or cat, but the following advice will help protect you and your family:

  • Hygiene - WASH YOUR HANDS. Particularly after scooping up poo or touching your pet. Always wash your hands before meals or preparing food

  • Try not to let your dog lick your face, particularly if you are immunocompromised, pregnant, young, elderly or if your dog is unwell

  • If you are pregnant or immunocompromised, ask another member of the household to clean up your pet’s mess. It is important to collect any poo from your garden daily to prevent contamination building up

  • Stop your dog eating poo (coprophagia) - easier said than done! But using a muzzle or keeping them on a lead in high risk areas will help

  • Avoid raw diets in households with people at risk - immunocompromised, pregnant, young, elderly

  • Take your dog or cat to the vet promptly if they have vomiting or diarrhoea. Clean up any diarrhoea as soon as possible and try to use a disinfectant

  • If your dog or cat has been having diarrhoea, wash their back end in diluted Hibiscrub to remove any contamination from their coat. You can soak them in this solution for 10 minutes and then rinse thoroughly

When to see a vet?

  • Vomiting and/or diarrhoea

  • Diarrhoea with blood or mucus

  • Lethargy

  • Loss of appetite or a decreased appetite

  • Weight loss

Further information

Diarrhoea and vomiting in dogs

Parvovirus infection in dogs

Help! My puppy is eating its poo

Feeding your dog or cat a raw food diet - What do you need to consider?

Still have questions?

If you would like more advice on nutrition or raw feeding, please book an online video appointment to have a chat with one of our FirstVet nutrition vets.

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