Proposed ages for sterilization

Supporting information for these recommendations can be found here.

Visit this printable algorithm for clients on spay/neuter timing.


Small Breeds

Large Breeds

6 months of age

Wait until growth stops (~9–15 months of age)


Small Breeds

Large Breeds

Prior to anticipated heat cycle (5– 6 months of age)

Wait until growth stops (~5–15 months of age)*

Small breeds: < 45 lbs projected adult body weight
Large breeds: ≥ 45 lbs projected adult body weight

*Use clinical discretion combined with comprehensive owner education in an effort to balance the benefit of decreasing mammary neoplasia and unwanted litters when done earlier (before the first estrus) versus decreasing the risk of orthopedic disease, some cancers, and urethral sphincter mechanism incompetence if performed later (after growth stops).

The 2019 AAHA Canine Life Stage Guidelines are supported by generous educational grants from Boehringer Ingelheim Animal Health USA Inc., CareCredit, Elanco Animal Health, Hill’s ® Pet Nutrition, Inc., IDEXX Laboratories, Inc., Merck Animal Health and Zoetis Petcare.