Every pet owner should have a conversation with their veterinarian about the pros and cons of spaying and neutering and decide together which is best for the pet. There are many benefits associated with these surgeries such as increased life expectancy, prevention of unplanned and unwanted litters and shelter overpopulation control.
For the majority of cats, spay-neuter performed at 4-6 months of age will serve them well. For dogs, your veterinarian will suggest a time based on the breed, behavior, and its environment. Generally 4-6 months of age is a good recommendation. For large and giant breed dogs, the decision may be to delay spay and neuter until the pet stops growing; however, there are additional risks and additional costs when they are older.
The decision should always be an informed decision made jointly by the owner with their veterinarian.