Why is my dog having diarrhoea?
Unfortunately, diarrhoea is a common condition that can affect dogs, but just because it is common doesn’t mean it is a straightforward issue to diagnose. Diarrhoea can range from mild softening of stools to severe watery stools with blood. The tricky thing is trying to work out WHY your dog is having diarrhoea.

We often recommend you bring in a fresh poo sample for the vet to take a look at and will be particularly handy if any poo tests need to be performed. Photos are also greatly appreciated, otherwise, your vet may have to think of some creative descriptions (e.g. “soft-serve ice cream”) to get a more accurate picture of the consistency of your dog’s stool. The Bristol Stool Chart may be used as a simple diagnostic chart to help classify your dog’s stool.

Your vet may also ask quite a few questions regarding your dog’s toileting habits including the frequency, volume, consistency, urgency and straining, as well as whether there was any blood or mucus in the stool. This will help determine if the diarrhoea is coming from the small bowel or large bowel or both.

What are the most common causes of diarrhoea?

1. Dietary indiscretion
This means your dog has eaten food that has simply not sat well with their tummy, whether it be changing their diet suddenly or giving a new treat. When introducing a new diet, it is important to gradually transition from the old to the new food slowly over 5-7 days. This will allow their stomach to adjust to the new diet without getting diarrhoea. Additionally, dogs are commonly known to eat things they shouldn’t be! Examples include:

  • Scavenging through the bin
  • Picking up the food your child has accidentally dropped
  • Being fed human food or table scraps eg. sausages and cheese
  • Eating plants that can be irritating or toxic
  • Eating human medication or toxins in the backyard/park eg. rat bait
  • Eating poop
  • Eating an object that is not digestible eg. a tennis ball

If your pet has eaten something high in fat (especially human foods or table scraps), they can also develop a very painful condition called pancreatitis.

2. Infections (worms, protozoa, bacteria, viruses)
Dog’s can pick up intestinal worms very easily from their environment. They are often not particular about what they eat and they may eat food contaminated with poop or step on infected poop whilst a walk and then ingest it while licking their paws. There are 4 types of intestinal worms: roundworm, hookworm, whipworm, and tapeworm. It is recommended to give your dog a worming tablet to protect them against infection. Nexgard Spectra is a 1-monthly chewable tablet that protects your dog against intestinal worms (roundworm, hookworm, whipworm), heartworm, fleas, and ticks. If you are feeding raw meat (we advise against this for health concerns and contamination risks), you will need an extra-intestinal worming tablet monthly to protect against tapeworm found in raw meat which is not covered by Nexgard Spectra.

A dog can also get diarrhoea from bacterial, viral, or protozoal infections. These causes are highly contagious, especially if they are fed a raw meat diet or come in contact with contaminated water (commonly after periods of recent rain).
Examples include:

  • Giardia (protozoal)
  • Coccidia (protozoal)
  • Parvovirus (viral)
  • Salmonella sp. (bacterial)
  • Campylobacter sp. (bacterial)

Unfortunately, we cannot determine if your dog has an infection based on just a physical examination. Instead, a poo test would be required to identify any infections.

3. Food allergy or intolerance
Dogs can develop a food allergy or intolerance to a particular ingredient in their food, the most common of which is actually to a type of protein! Examples of common protein allergies include:

  • Chicken
  • Beef
  • Lamb
  • Egg

It is very rare for a dog to have grain or wheat intolerance. If you suspect your dog has a food intolerance or food allergy, it is important to talk to your vet about a plan. This may involve a food elimination trial on a special allergy diet for 6-8 weeks, then a re-challenge. If diarrhoea resolves on the trial and returns on the re-challenge, it may indicate a food allergy and a special allergy diet will need to be fed long-term.

For dogs with chronic or a recurrent history of diarrhoea, we may be a bit more suspicious of inflammatory bowel disease (IBD). This is where the lining of the intestine is constantly inflamed and irritated due to an allergic-type response. This is often diagnosed by the exclusion of all other common diseases.

Causes of diarrhoea outside of the gastrointestinal tract
Diarrhoea can also be caused by other serious issues in the body. Generally these diseases are related to older animals. This may include:

  • Kidney disease
  • Liver disease
  • Adrenal gland issues
  • Pancreatitis (especially after being fed foods high in fats/oils)
  • Cancer

To assess these issues, a blood test may be recommended as an initial diagnostic screening test.

How do I treat my dog’s diarrhoea?
The treatment of diarrhoea will vary depending on the type and cause of diarrhoea. Your vet may recommend diagnostic tests such as a fecal test, abdominal imaging, and/or blood test to help determine the cause and subsequent treatment options. Some of the more common treatment options include:

  • Digestive care ‘bland’ diet: It is common knowledge to give your dog a ‘bland’ diet during gut upsets to give their gut a break by feeding easily digestible foods. We often recommend Hill’s Prescription Diet (i/d) digestive care as it is a complete and balanced, high-energy nutritionally-dense diet, instead of the traditional home-cooked chicken and rice diet.
  • Probiotics & prebiotics (e.g. Prokolin paste): The gut contains a dynamic population of microorganisms, mostly bacteria, that play a key role in digestion and an imbalance in this can be the cause of diarrhoea. Probiotics are often called ‘good bacteria and prebiotics are types of dietary fibre that feed the ‘good bacteria in your gut and allow them to flourish. The addition of prebiotics and probiotics can help restore any imbalances and promote a well-functioning gut.
  • Medications against infections (depending on poo test results): Often a fecal test is recommended to assess for infections. The most common parasite in our local area is a type of water-borne protozoan called giardia which requires an oral liquid anti-parasitic medication to treat. Antibiotics are actually very rarely indicated unless there is a bacterial infection. We do not reach for antibiotics lightly as it can actually cause an imbalance in the gut microbiome and make diarrhoea worse!

In summary, if your dog is feeling unwell and having diarrhoea, it is best to contact your veterinarian at My Vet Animal Hospital. It is important to support and treat your dog and make sure they are not dehydrated because they will be losing a lot of fluid through their diarrhoea.

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