Brown and white dog lying down

The most common trigger of colitis is stress.

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Colitis in dogs: symptoms and treatment

By Dr Karen Ingleby BVetMed MRCVS Veterinarian

Updated on the

If your dog has frequent diarrhoea or soft faeces with blood, they may well have colitis.

The word ‘colitis’ means inflammation of the large intestine, specifically the colon. It affects many different species, including humans, and can be a chronic condition that happens day in and day out, or has sudden flare-ups.

Colitis is a disease that upsets the gut’s ability to digest properly and is often accompanied by discomfort, diarrhoea or trouble passing stools.

What are the symptoms of colitis in a dog?

Colitis symptoms can vary but include: frequent diarrhoea or soft faeces containing blood or mucus (or both), straining or pain when passing a stool (which can sometimes be mistaken for constipation), lack of appetite or disinterest in food, flatulence, vomiting and generally looking like they have a painful abdomen by standing or sitting with a hunched back.

What is the main cause of colitis in a dog?

Colitis can be caused by various things, but the most common trigger is stress. Colitis be an acute or sudden illness that can be caused by: eating something unusual that causes gut irritation; gut trauma; bowel tumours; a bacterial or viral infection; or worms or other parasites. Unfortunately, some dogs have a form of colitis that comes and goes throughout life: chronic colitis. The causes of chronic colitis include food allergies and immune-mediated disease (your dog’s defences attacking their own colon) in the form of Inflammatory Bowel Syndrome (IBS).

What are the warning signs of colitis in a dog?

One of the most common symptoms dog owners report is seeing frequent, small volumes of semi-formed to liquid faeces. Many dogs will look like they are straining during and after passing a stool, and small amounts of bright red blood will often be passed near the end of their motion.

How is colitis in a dog diagnosed?

After an examination and discussion with a vet about diet and changes in your dog's life that may have resulted in increased stress levels, the vet is likely to ask you to bring in your dog's stool sample. This will be tested for worms and parasites. The next step often involves x-rays and ultrasounds of the abdomen and, in some cases, taking a small piece of the colon (a biopsy) may be needed.

How do you collect a poo sample from your dog?

If you've contacted a vet and they've requested a sample, they may have given you a specific sample pot that often has a little spoon attached to the lid. If you do not have a sample pot, use a clean container or a poo bag.

Take your dog for a walk and watch them closely to see where they defecate. Then wearing gloves, pick up the sample. If you are using a pot from the vet, at least half fill it if possible and then put the lid on tightly. If you are using a different container or poo bag, pick up the faeces then put on a clean lid or tie a knot in the bag. Make sure you mark the sample with your dog's name and the date and time the sample was taken and then drop it into the vets.

What do dog stools look like with colitis?

A stool from a dog suffering with colitis usually looks like diarrhoea or soft faeces containing red blood or mucus.

How do you treat colitis in dogs?

The cause and type of colitis will determine the most appropriate treatment. Initially your dog will usually be placed on a fast for a day or two, before beginning to re-introduce a diet that is high in fibre, or specifically intended to treat dogs with food allergies (hypoallergenic).

Antibiotics may be prescribed, depending on your dog's diagnosis, and administering a worming treatment is also commonly used as part of a wider treatment plan. Anti-inflammatory or immunosuppressive drugs may be used in cases of inflammatory or immune-mediated colitis and to reduce the pain.

If your dog is very ill or has been suffering from the condition for a long time, they may be admitted and then monitored and given IV fluids. In rare cases, surgery can be needed to remove sections of the colon. Colitis is usually a one-off problem and, following treatment, most dogs will recover within a few days. Cases of chronic or episodic colitis can take quite a few weeks to improve, but can be very well managed with ongoing treatment and diet.

What foods trigger colitis in a dog?

Dietary intolerance, especially an allergic reaction to certain preservatives, colourings or foods such as protein or fat-rich foods, can trigger colitis, as well as causing lactose intolerance. If you give your dog any type of a dairy product, including cheese, you may be causing this inflammation.

If the colitis it is part of an allergenic reaction to a certain ingredient within their food, finding out what this allergenic trigger is and removing it from your pet’s diet is an important part of managing the condition. Yet any type of spoiled food or a sudden change in your dog’s diet may lead to the acute form that usually ends as soon as it passes entirely from your dog’s system.

What is the best food for a dog with colitis?

You’ll need to find out what the allergenic trigger in your dog’s food is that’s causing the reaction. Then you can remove that from their diet. Feeding a diet that is especially designed for dogs with dietary sensitivities can help to reduce bouts of colitis. While not all forms of canine colitis are caused by allergies, foods designed for dogs with allergies will tend to be a good fit for dogs with the condition, as they tend to be simple foods with fewer ingredients than store brands. A vet will be able to advise you on the best options for food for your dog.

How can I prevent my dog suffering from colitis? 

To prevent this, there are various steps that you can take. Firstly, make sure that your dog is wormed regularly using a product recommended by a vet.  Next, feed your dog a balanced diet and don’t allow it to scavenge or eat food that they are not supposed to, especially when out on walks. Avoid making sudden changes to your dog’s diet. If you are changing the food, do it over a period of days, gradually reducing one and increasing the other food.

Also, if you know your dog is prone to colitis, try to keep your dog’s stress levels to a minimum to avoid flare-ups. Or, if you know they are going to have a stressful experience like kennels or fireworks, speak to a vet about possible preventative treatments. If colitis occurs due to another condition, such as IBS, then treatment of the underlying condition will be necessary to resolve the bout of colitis.

When should I see a vet?

Contact a vet if your dog has regular loose faeces with blood or mucus, or appears to be in discomfort when try to pass a motion. It can be helpful to take a poo sample (or a photograph of your dog's poo) to show the vet.

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