The term ‘gastroenteritis’ means an inflammation of the stomach and intestines. It’s usually pretty obvious if your cat is suffering from gastroenteritis because they may be sick or have watery, soft or bloody poo. Although cat diarrhoea may be difficult to spot if your cat goes outside to go to the toilet, vomiting is usually very noticeable because it takes them as much by surprise as it does you.

As you can imagine, especially if you’ve ever experienced this yourself, having gastroenteritis is pretty unpleasant for cats. Gastroenteritis can be acute (sudden and short-lived) or chronic, which means it goes on for more than two to three weeks. These longer cases are termed chronic enteropathies (CE), the most common form being Food Responsive Enteropathy (FRE). Chronic enteropathy was previously known as inflammatory bowel disease (IBD).

Acute gastroenteritis isn’t always a veterinary emergency, and some cases may get better on their own, but there are times where action is needed. In this article, we’ll look at the most common causes and what you can do to help your cat when they’re feeling poorly.

Common causes of acute gastroenteritis

1. Dietary indiscretion

While dogs are the poster children for raiding the bin, cats can fall victim to this too. Lots of cats may sneakily steal food from worktops or eat an unfortunate creature that doesn’t go down too well. These kinds of issues usually resolve pretty quickly on their own. This could also happen if you changed your cat’s food recently but didn’t transition to the new food over the course of several days.

2. Stress

Cats that live indoors-only or with one or more other cats can be chronically stressed. This is detrimental in the long term and can cause many clinical signs, from life-threatening bladder blockage and renal failure to intermittent gastroenteritis, excessive grooming and hair loss.

3. Viral infections

These can cause acute gastroenteritis in almost any animal, including cats. This is just one of the reasons to keep your cat’s vaccinations up to date.

4. Parasites

Parasites, especially in large numbers, can be problematic for the intestines. Talk to your vet to make sure your parasite control is adequate for your cat’s lifestyle. For example, cats that hunt and eat their prey may need worming more frequently than a sedentary house cat.

5. Food sensitivities

Also known as adverse food reactions (AFR), these include food allergies and intolerances. Cat food allergies have an immune component and tend to stem from protein sources. The most common cat food allergies are to beef, fish, chicken and dairy. Intolerances can be to any nutrient or additive. You don’t really need to get hung up on the differences between allergies and intolerances because the treatment is the same for both.

6. Other medical issues

Gastroenteritis can be caused by other diseases, such as kidney failure or an overactive thyroid gland (hyperthyroidism).

7. Medications

Some medications, such as non-steroidal anti-inflammatory drugs (NSAIDs), can be gastric irritants in cats. NEVER give cats any medications that are not labelled for use on cats.

What to feed a cat with gastroenteritis

If your cat has an upset stomach but seems fairly bright, you could try to manage it at home for 24 hours.

  • Ask your vet for a bland, highly digestible ‘recovery’ food. These help the gut to heal and restore the all-important cat microbiome.
  • Feed your cat smaller meals more often. All cats have evolved to eat lots of small, frequent meals and have quite simple, relatively short gastrointestinal tracts. Even healthy cats benefit from 5-6 meals a day (timer feeders are very useful for this), but for cats that have an upset stomach, it’s even more important.
  • Don’t withhold food unless your cat is actively vomiting. Having food is very important for recovery of the GI tract.

When should you see your vet if your cat has gastroenteritis?

Cat gastroenteritis often resolves on its own, but it can be very serious in certain circumstances. Always seek veterinary help if:

  • Your cat won’t stop vomiting or you see blood in their vomit or diarrhoea. This includes if you see vomit that looks like coffee grounds or if stools are very dark or black.
  • The gastroenteritis goes on for more than 24 hours.
  • Your cat is depressed or reluctant to eat.
  • Your cat seems to be in pain, including if they are acting withdrawn or won’t play.
  • You think your cat is dehydrated. A simple test you can do for dehydration is the ‘skin tent’ test. When an animal is well hydrated, if you gently pull the skin on the back of the neck up and let go of it, it will drop smoothly back into place. If your cat is a little dehydrated, it will be slower to return to position. In severe dehydration, it stays poking up like a tent, hence the name of the test.
  • If your cat gets better on their own but you notice that they have regular bouts of stomach upset, you should see your vet, as there may well be an underlying cause, such as a food sensitivity or underlying medical issue.

If your cat needs veterinary attention, it’s really useful if you can take a sample of your cat’s vomit or stool with you. Your vet can test for parasites, infection and the presence of things like blood. Depending on the initial clinical exam, your vet may want to:

  1. Give your cat a high-quality, highly digestible food to support your cat’s digestion for a few days and help the gut heal.
  2. Treat your cat for any parasitic or bacterial disease that is found.
  3. Do blood tests to rule out other diseases.
  4. In cases of dehydration, keep your cat in the hospital overnight to administer intravenous fluids and supportive care.
  5. In some cases (for example, if the signs of gastroenteritis become chronic or recurrent), order x-rays, imaging and even biopsies.
  6. Do a food elimination trial for adverse food reactions.

Fundamentally, you know your cat better than anyone. If ever you are concerned, please don’t hesitate to ring your vet. We would always rather be safe than sorry and, as with all things health-related, the sooner you get help, the better.

Frequently Asked Questions about feline gastroenteritis

What are the symptoms of gastroenteritis in cats? 

The most common signs of gastroenteritis are vomiting and diarrhoea. The latter may be difficult to spot if your cat goes outside to go to the toilet.

Can cats recover from gastroenteritis without treatment? 

Yes. Just like humans with an upset stomach, many cases resolve on their own. However, if your cat still has symptoms after 24 hours, seems lethargic or depressed, or if you see blood in their vomit or stools, you should seek swift veterinary attention.

How do I know if my cat has a food allergy or gastroenteritis? 

Your vet will do a number of tests to find the cause of your cat’s gastrointestinal problems. Don’t try to diagnose or treat at home, as you may delay diagnosis and your cat could become very ill.

Is gastroenteritis in cats contagious? 

Some forms of cat gastroenteritis are caused by viral or bacterial infections that can be dangerous to other cats. Always err on the side of caution and talk to your vet if you’re concerned. Always keep your cat’s vaccines up to date.

Reviewed by Becky Mullis, DVM, DACVIM (Nutrition) and Emma Milne BVSc FRCVS.

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