Why Cats Vomit

Cats often vomit as a result of hairballs, eating grass, or eating too rapidly. Eating grass and throwing it up is not a sign of illness if there are no other symptoms. This is a common, natural behaviour (for theories on why cats do this, see Why Cats Eat Grass). Grass-induced vomit is usually clear with whole blades of grass in it.

Hairballs, another common cause of vomiting in cats, only require medical attention in severe cases. If the problem is hairballs, the vomit will have a tight, hair-containing clump. Hairballs can usually be prevented by brushing the cat regularly and using medication or food formulated to prevent them (for detailed information on hairball remedies, see Preventing Hairballs in Cats).

Cats may also vomit because they eat their food too rapidly. In such cases, the vomit tends to be solid and full of undigested food. Feeding the cat smaller meals more frequently and feeding cats in separate rooms in multi-cat households (cats may gobble their food to prevent other cats from eating it) will often solve the problem.

Cats have sensitive stomachs, and changing their diets rapidly can cause vomiting. It’s best to make dietary changes gradually over time by mixing increasing amounts of the new food in with the old until the switch has been made. A food allergy may also cause vomiting, though it’s more likely to cause itchy skin or diarrhea.

More serious causes of vomiting in cats include:

• Intestinal parasites
• Liver disease
• Central nervous system disorders
• Feline panleukopenia (sudden vomiting with fever, particularly in young cats)
• Inflammatory bowel disease
• Tonsillitis/sore throat
• Infected uterus (also called acute metritis)
• Ingestion of substances toxic to cats
• Peritonitis
• Chronic renal insufficiency (CRI), also known as chronic renal failure (CRF)
• Infectious diseases
• Hyperthyroidism
• Obstructions (swallowed objects)
• Intestinal or stomach tumours
• Chronic gastritis (often accompanied by diarrhea)
• Pancreatitis
• Heartworm infection

How to Tell If It’s Serious

An otherwise healthy cat that vomits just once or twice and is perfectly normal before the incident and afterward is probably not seriously ill. However, if the cat has not recently eaten food or grass, is not vomiting up hairballs, and shows other signs of illness, there may be a more serious problem. Symptoms of serious illness include:

• Persistent vomiting – A cat that continues to retch or bring up clear, frothy liquid after initially vomiting may have ingested spoiled food or have a disease that irritates the lining of the stomach, such as infectious enteritis (persistent vomiting isn’t always an indication of a serious illness – hairballs or grass may also cause it).
• Sporadic vomiting – A cat that vomits on and off over days or even weeks and not directly after meals may have kidney or liver disease, chronic gastritis, heavy worm infestation, irritable bowel syndrome, diabetes mellitus, or a severe case of hairballs that requires medical attention. Sporadic vomiting combined with listlessness, a haggard appearance, and loss of appetite indicates a serious problem.
• Vomiting blood – A cat vomiting blood or material that resembles coffee grounds may be bleeding internally.
• Vomiting feces – When a cat vomits material that resembles and smells like excrement, the most likely causes are peritonitis, intestinal obstruction, or abdominal injury.
• Projectile vomiting – If a cat vomits so forcefully that stomach contents are ejected further in front of the cat than with normal vomiting, it could indicate a number of things, including hairballs, foreign objects in the stomach, tumours, encephalitis, or blood clots in the brain.
• Vomiting worms – Kittens that are severely infested with roundworms may vomit up adult worms.

When in Doubt, See a Veterinarian

Treatment for persistent vomiting in a healthy adult cat with no other symptoms involves withholding food for 12-24 hours. A cat that continues to vomit even when food is withheld requires a visit to a veterinarian or local animal emergency clinic, where a veterinarian may prescribe anti-emetics (to stop the vomiting), antacids (to coat the stomach), and/or other medications (to soothe the gastrointestinal tract).

A cat that is vomiting continuously can quickly become dangerously dehydrated, especially if the cat also has diarrhea (kittens, senior cats, and cats with pre-existing medical conditions are particularly vulnerable). Seek veterinary care immediately if:

• Vomiting is persistent (continuous and unrelenting).
• Sporadic vomiting carries on for more than 24 hours
• The cat becomes dehydrated (check for dehydration by gently pinching some skin on the back of the cat’s neck – if it doesn’t spring back immediately, the cat is dehydrated)
• There are secondary symptoms of illness such as diarrhea, fever, weakness, lethargy, or blood or feces in the vomit
• You suspect that the cat may have ingested a toxic substance

If you’re not sure whether or not the problem is serious, err on the side of caution and consult a veterinarian. Bringing a sample of the vomit can help the veterinarian make a diagnosis.

Once the vomiting stops, when reintroducing food, it’s a good idea to offer a bland diet initially. A meat-based baby food that does not contain onions (which are toxic to cats) may be fed temporarily. This food is not nutritionally complete for cats and should only be used when initially encouraging the cat to eat again.

A cat that regularly vomits as a result of another medical condition such CRI may require prescription medications to correct salt imbalances, dehydration, and weakness. In severe cases, a hospital stay with intravenous fluid support is necessary.

For more cat articles, see the main Cats page.

This article is provided for informational purposes only and is not intended as a substitute for veterinary consultation and care.