All cats should be spayed or neutered by the time they are six months of age. Cats who are neutered or spayed live longer, healthier lives than those who are left intact, and many generally become more affectionate.
Neutered (or castrated) males will not have a tendency to spray to mark their territory, and if they are allowed to go outside, they will not be as inclined to fight with other cats or wander the neighborhood. Neutering is a simple procedure and may require an overnight stay in the vet's office.
Spaying a female is a little more involved and is often more expensive than neutering. She will undergo surgery to remove her reproductive organs and also will need to spend the night in the veterinary clinic. A spayed female will not go into heat or cry to be let out to look for a mate.
If you adopted your cat or kitten from an animal rescue organization or shelter, he may already be altered. Many pet organizations spay or neuter all animals they put up for adoption to avoid contributing to the pet overpopulation problem.
Bring your child to the vet's office for an educational experience. Depending on her age and level of understanding, you can explain why your cat needs to see the vet (or cat doctor) even if the animal is not sick. Some older children are very interested in their pet's health care and will be happy to be included in the exam room at this time.
Ask the vet to explain each step of the process during the checkup. If your child has questions about the cat's general behavior or health care routine, encourage her to ask the vet directly. Most are happy to answer questions from children and are pleased to see them taking responsible role in pet care.