Ask the Vet: Why do cats vomit? by Kristel Weaver, MPVM, DVM

I have 2 kitties and one of them throws up a ton!  I know people say that cats throw up; it's no big deal.  Why do cats vomit? 

Most cat owners have experienced the unpleasant surprise of finding a pile of cat vomit.  Fortunately, at my house I have two dogs to clean up the mess!  Before we discuss vomiting, we have to discuss the differences between vomiting and regurgitation.  Vomiting is an active process that involves stomach noise, retching and heaving before the food is expelled from your cat’s mouth.  Regurgitation is a passive process where the food just pops out, often undigested in a tube or cigar shape.  There are several reasons for cats to regurgitate or vomit:

• Gorging – Cats that eat too much too fast may regurgitate from triggering a stretch reflex in the stomach.  These cats regurgitate right after eating and the food is undigested in a tubular shape. It can also look like a round pile of undigested food.

• Hairballs – Cats spend a lot of time grooming.  In the process, they eat a lot of hair.  Some cats are able to pass hair through their digestive tract into their stools.  For other cats the hairball grows in the stomach until it causes irritation and is vomited up.  Hairballs look like vomit mixed with hair.

• Grass or other foreign bodies – If a cat eats something other than food such as grass, leaves, plastic or a hair band, it may lead to vomiting.  Obviously in this type of vomit you will see some non-food item that was probably the cause of that vomit.

• Food allergies – These are VERY common in cats.  When cats have a food allergy they are allergic to either the protein or the carbohydrate in their food.  For example, a cat that vomits frequently on a fish based cat food might do much better on a turkey-based food and eliminating fish from their diet completely.  If you think your pet has a food allergy, talk to your veterinarian about recommended foods.

• Constipation – Cats that pass a dry hard stool every few days may be constipated and vomit from feeling bloated and plugged up.

• Other health issues – Cats vomit due to metabolic disease, inflammatory bowel disease, toxins, cancer and a variety of other illnesses.

When should I be concerned?  

If your cat vomits several times a day, if there is blood in the vomit, if your cat is lethargic, losing weight or not eating then I recommend taking your cat to the vet as soon as possible. 

Usually, a cat that vomits once or twice a month is not a concern.  If your cat vomits or regurgitates more often than you feel is normal, I recommend discussing it with your veterinarian.  

Dr. Kristel Weaver is a graduate of the Veterinary School at the University of California, Davis where she received both a DVM and a Master’s of Preventative Veterinary Medicine (MPVM).  She has been at Bishop Ranch Veterinary Center & Urgent Care in San Ramon since 2007.  She currently lives in Oakland with her husband and their daughter, Hayley. If you have questions you would like Dr. Weaver to answer for future articles, please email info@webvets.com