Cats can have a swollen tummy due to many different illnesses. Free fluid accumulation is the most common reason for the swelling.

Cats can have different types of fluid inside their tummy, or abdomen. The type of fluid depends on the cause and determines treatment. Feline infectious peritonitis is a common illness in outdoor, multi-cat households. It causes fluid build-up in the tummy and can be fatal if untreated.

What to do if your cat has a swollen tummy

Check your cat for wounds or signs of trauma. If you find something, see a vet straight away, even if it appears mild on the surface.

Monitor their breathing: if they are struggling to breathe or have grey gums, see a vet in practice immediately.

Monitor their appetite, behaviour and water intake. Speak to a vet if you notice any changes.

Check the litter tray for urine and poo. Speak to a vet if you’re unsure if they have urinated in the last 12 hours or pooed in the last 48 hours. Also consider any other symptoms, such as vomiting or diarrhoea

If you have an entire female with access to the outdoors, pregnancy is a possibility as early as 4 months of age.

Common causes of a swollen tummy in cats

• Digestion problems:

  • Eating something they shouldn’t have or a sudden change in food will disturb the bacteria that live in the gut and make them produce gas

  • Being constipated and not passing as much poo as normal

• Obesity

• Worms: especially in kittens, if they have a high burden of roundworms, they can have large bellies.

• Fluid inside the tummy (ascites): can happen for several reasons and with several types of fluid, such as blood, clear liquid, pus or urine.

  • Traumatic injuries, such as falls, accidents and bite wounds, can introduce infection into the tummy or cause leaking from internal organs, such as the bladder and intestines.

  • Feline Infectious Peritonitis (FIP) is caused by a virus and causes severe disease and fluid build-up in the tummy, especially in young kittens.

• Pregnancy

• Tumours

When to worry about a swollen tummy in cats

Seek help from a vet in practice immediately if your cat:

• Has a swollen tummy that developed quickly and if accompanied by difficulty in breathing

• Is constantly going into their litter without passing anything

• Is very flat and not interested in interacting with you

• Has a painful tummy

Joii can help if:

• Your cat’s bloated tummy has come on gradually and is associated with:

  • Diarrhoea

  • Flatulence (wind)

  • Vomiting

• You are worried about a kitten with a wormy tummy

• Your cat has eaten something they shouldn’t

• Your cat is passing less poo than normal

• Your cat is not eating or drinking properly

• You need to discuss your cat’s diet

• You would like to talk about worming your cat

• You would like advice on your cat’s behaviour

Tips to prevent your cat from having a swollen tummy

• Feline Infectious Peritonitis is most common in homes with many cats and outdoor access. A vaccine has been developed but does not seem to be very effective and is not available in the UK.

• Frequent cleaning of litter trays will help prevent many problems

• Treatment for intestinal worms is important, especially in young kittens and future mothers. The right protocol depends on lifestyle, where the cat lives and other factors.

• Eating too much or too quickly can be prevented by offering food in small portions and using special bowls or toys.

• If your cat has had multiple urinary issues, the right food may help prevent or reduce these

How a vet will know what’s causing your cat’s swollen tummy

Finding out what is causing a swollen tummy may require that your vet perform a few different tests.

• If there is fluid in the abdomen (ascites) a sample of this will be taken to examine in the lab. Blood tests are usually also needed to check protein levels and organ function

• If the swelling is from a distended bladder, blood tests are done to check kidney function and electrolyte imbalances

• If there is constipation or a mass, x-rays and/or an ultrasound scan can provide valuable information

Home treatment for swollen tummy in cats

If there are any breathing issues, pain or your cat is very lethargic speak to a vet straight away. It is also advisable to speak to a vet if your cat is straining.

If the swelling isn’t bothering a young cat too much and develops after a large meal or trying a new food, they may just need to rest for a few hours. Do not feed them anything else for 6-12 hours. If they aren’t any better then speak to a vet.

The vets at Joii are happy to help if you have any concerns.

How the vet will treat your cat with a swollen tummy

The treatment for a swollen tummy will depend on the cause.

• Feline infectious peritonitis is treated with a long course of antiviral medication, and may also require supportive care such as draining of the fluid or appetite stimulants

• Constipation may require laxatives or enema under sedation

• A blocked bladder will need to be emptied under sedation and supportive treatment

• Wormers if the swollen tummy is caused by intestinal parasites

Some problems, like pregnancy, overeating or excessive gas production, will resolve on their own.

Are some cats more at risk of a swollen tummy than others?

• Large groups of cats living together, such as breeding catteries, are at higher risk for FIP, as are cats that have been infected with Feline leukaemia virus and Feline immunodeficiency virus.

• Constipation is more common in older and long-haired cats.

• Kittens are at higher risk of worms and other infections

Other causes of swollen tummy in cats

• Eating something they shouldn’t.

• Heart disease

• Obstructions caused by foreign bodies

• Megacolon

• Pyometra