My 3 years old integer tomcat never vomits a hairball. He is not constipated. He eats normally (free meals). Three months ago he vomited twice, yellow liquid, but no hairball. Vet said it can be just a result of not feeding for more than 12 hrs (no reason identified). No medication given. I also noticed that the my cat does not lose hair. At all. I could not find any clear reference whether not vomiting hairballs is natural/normal. I highly appreciate your opinion and/or links.