Our question this week was:
Doctor - I noticed today in my cats vomiting a slight traces of blood, he sometimes vomits because of the hairballs and it is noticeable in his vomiting, but today when I saw this slight blood which is the first time I was really very concern of my cats health, what's the problem?
Hi Nidal - thanks for your email. You wrote that your cat had blood in his vomit. I'm not sure based on your description if the blood is from the stomach or esophagus. Either way, I'd recommend that you call your veterinarian and have him checked.
There are several causes for blood in the vomit - from toxins, irritants, drugs, cancer, etc.
An article that might be helpful to you is Hematemesis (Vomiting Blood) in Cats. I think this will help to answer some of your questions.
Best of luck!