Well, if your cat threw up one worm it's pretty safe to say he or she has more worms and you should describe the worm to your vet and have him/her treated for it as soon as possible. If you have more than one cat they should all be treated.

Usually worms come from cats eating an infested small rodent, coming in contact with infested feces, or getting bit by an infected flea- not from undercooked canned food which is usually heavily preserved and very well cooked, even if it's cheap stuff. If it was a tapeworm your cat should be checked for fleas, and if he/she hasn't been outside you should be on the look out for signs of mice in the house.

Cali answered on 1/29/12. Helpful? / 0