When to spay or neuter a Rottweiler?
At what age should I consider getting my rotties spayed or neutered?
Generally it is recommended that you have a pup spayed or neutered before they are 6 months old. Researchers and veterinarians believe that this allows for the maximum health benefits of the surgery - in terms of preventing reproductive-order diseases and conditions.
If a pup or dog is older than this, that doesn't mean they shouldn't be 'altered', just that the benefits of the surgery in terms of disease prevention may be less. It's still going to prevent pregnancy and heat cycles in females, and minimize male-hormone related behaviors such as spraying/marking, wandering, male-to-male aggression and so on in males.