Spay / Neuter
DOGS
Dogs not used for breeding should be neutered or spayed AFTER 6 months of age.
MALE DOGS
Male dogs can be neutered at ANY time after 6 months. They seem to recover easiest with little to no swelling if done before 1 year. However, dogs over 1 year if kept appropriately confined for 10-14 days post op can also do fine with minimal swelling or bruising. There is no scientific evidence that earlier castration or later castration prevents cancer (except testicular of course!).
FEMALE DOGS
It is best to spay females BEFORE their first heat cycle to eliminate any future occurrence of mammary cancer. There are some sources/breeders that suggest a female dog should have at least one heat cycle for bone growth or to prevent other cancers, there is NO DATA to support this in the scientific literature.
CATS
Cats not used for breeding should be neutered or spayed at 6 months of age.
MALE CATS
Should be neutered/castrated AT 6 months. Beyond 6 months you risk the male cat starting to spray urine to mark in your house.
FEMALE CATS
Should be spayed AT 6 months. Cats that are allowed to go into heat simply stay in heat and often do not come out. Ever notice why there are so many kitten in the world?