Cats vomiting causes

Question
I had a siamese mix cat, she had been vomiting sometimes after came back from my back yard. I saw her eating grass sometimes too. I think this can be part of the problem for she been vomiting. Do you know if can be something else that cause this?

I will appreciate any help or suggestions.

Answer
Hi, Nitza.  There are lots and lots of causes of vomiting.  Since your cat goes outside, I'd be willing to bet she's got parasitic worms.  The most common one is the roundworm, which live in the stomach and intestines.  They make a cat really sick to their stomach and cause the cat to throw up.  They can cause diarrhea and gas, too.  If you are in the U.S., you can get medication to treat these at pet stores or through your vet.  The proper medication will contain the ingredient pyrantel pamoate.  There is no harm in giving this medication, even if you don't see worms in the vomit.

Another worm that sometimes causes vomiting is the tapeworm.  This needs to be treated with praziquantel.  In the U.S., it is available without a prescription or through your vet.  The non-prescription item is called Tape Worm Tabs.

But vomiting can be caused by other things such as cancer, viral illnesses, protozoan illnesses, food intolerances (which Siamese are notorious for), and inflammatory diseases like Inflammatory Bowel Disease.  It is really urgent that you get your kitty to the vet to have her checked out and treated properly, since most of these illnesses require prescription treatment.