If the cat does not get the third shot, it may result in no antibodies in the body, or it may not have an impact on the antibodies. It depends on the cat's own situation. It is best to take the cat for the third shot, especially if there are many cats in the home. Case. If you don’t want to take your cat for a third injection, it’s best to take your cat to a pet hospital to check whether there are antibodies in the cat’s body. If there are antibodies, you don’t need to get them. If you don’t have antibodies, you need to get them.