What there is to weigh about neutering changes with the timing. Enter the species, the sex, the projected adult weight and the current age in months, and this guide shows the recommended window, the weight band it came from, and where the current age sits in that window.
The basis is the AAHA guidance on canine neutering age. Below a projected adult weight of 45 pounds, about 20 kg, it recommends 5 to 6 months for females before the first heat and 6 months for males. At or above that weight it recommends 9 to 15 months for males, after growth is complete, and 5 to 15 months for females. Guidance current as of October 2026.
For cats, the guide follows the 2021 consensus backed by AAHA, AAFP and others: spay or neuter before 5 months of age, for males and females alike, since the first heat and unplanned litters can start around then. It uses no table of months by breed, and it does not estimate surgery cost, recovery time or anesthetic risk. When growth itself ends belongs to a separate tool. This tool is for reference only and does not replace veterinary care. Contact your veterinarian right away if you notice symptoms or suspect a problem.
Frequently Asked Questions
The 2021 consensus backed by AAHA, AAFP and others recommends spaying or neutering cats before 5 months of age. If your cat is already older, it is not too late; schedule it with your veterinarian.
The AAHA guidance sets a different recommended window on either side of a projected adult weight of 45 pounds, about 20 kg. That single split changes the window even for dogs of the same sex.
The window is general guidance, and passing it does not rule the surgery out. What there is to weigh does change with timing, so review the current situation with your veterinarian and decide together.