The right age depends on breed.
Our recommended window for 223 breeds, mixes and cats, plus the research.
When should you spay or neuter?
Pick a breed (223 listed) or your dog’s expected adult size. Our windows follow the 2019 AAHA guidelines, with UC Davis breed research layered on top.
Not sure how big your puppy will get? Try our Puppy Size Estimator.
How we time spay and neuter
Sex hormones help signal growth plates to close. Remove them too early in a growing dog and the long bones keep growing a little longer, which can change joint angles and raise the risk of hip and elbow dysplasia and cruciate ligament tears. Small dogs finish growing early, so this matters far less for them.
The 2019 AAHA Canine Life Stage Guidelines split dogs at 45 lb of expected adult weight: smaller males neutered at about 6 months and females spayed before their first heat (5 to 6 months), and larger dogs once growth stops (roughly 9 to 15 months). Dr. Ameis applies that framework with a bit more room by size:
- Small (under 25 lb): 6 to 9 months
- Medium (25 to 50 lb): around 12 months
- Large (50 to 90 lb): around 12 months
- Giant (over 90 lb): 12 to 18 months
- Cats: by 5 months
What UC Davis added
Researchers at UC Davis followed thousands of dogs and in 2020 published breed-by-breed findings for 35 breeds, plus a study of mixed-breed dogs: those growing past about 44 lb had more joint disorders when neutered before a year, while smaller dogs showed no increase at any age. When a breed’s data point to waiting longer than our size window (male German Shepherds and Boxers, for example), the tool flags it.
Females and the first heat
Spaying before the first heat gives the strongest protection against mammary tumors, and that benefit shrinks with each heat cycle. Intact females can also develop pyometra, a serious uterine infection that affects roughly 1 in 4 by age 10 in some studies. For small dogs we aim to spay before the first heat. For larger females, joint health argues for waiting, so some have one heat first. We weigh it with you.
It’s still a family decision
These are population averages. A female in heat in an apartment building, a male who escapes the yard, or a household that can’t prevent accidental breeding may change the math. We’ll make a plan together. See our Puppy & Kitten Care page for the rest of the first year.
Common questions
What age do you recommend for spaying or neutering a dog?
It depends on adult size. We aim for 6 to 9 months for small dogs (under 25 lb), around 12 months for medium and large dogs, and 12 to 18 months for giant breeds over 90 lb. This follows the 2019 AAHA guidelines, which recommend waiting until growth stops in dogs 45 lb and up.
What is the best age to neuter a Labrador or Golden Retriever?
We generally recommend about 12 months for both. In the UC Davis study, male Labradors did best neutered after 6 months and females after 1 year, and male Golden Retrievers after 1 year. For female Goldens, spaying at any age was linked to more cancers, so we discuss options individually.
Is it OK to spay or neuter a small dog at 6 months?
Yes. AAHA recommends neutering small-breed males at about 6 months and spaying females before their first heat. UC Davis found no added joint or cancer risk at any age for most small breeds, including Chihuahuas, Yorkies, Maltese, and Pomeranians. Female Shih Tzus were an exception, where researchers suggested waiting until 2 years.
When should I spay or neuter a giant breed like a Great Dane or Bernese?
Usually between 12 and 18 months, once growth is finished. Giant breeds grow for a long time, and waiting supports joint development. Some breeds, like male Bernese Mountain Dogs, showed benefits from waiting even longer in UC Davis’s data.
When should I spay or neuter my cat?
By 5 months old, before the first heat. This is the veterinary consensus known as Feline Fix by Five.
Doesn’t LA law require spay/neuter by 4 months?
The City of Los Angeles requires most dogs and cats to be spayed or neutered by 4 months. A veterinarian’s letter can extend that by 60 days when surgery is scheduled, or longer for documented medical reasons, and there are exemptions for show dogs, guide and service dogs, and licensed breeders. Other cities, including West Hollywood and Beverly Hills, set their own rules.
Let’s plan it together.
Spay and neuter from $650, monitored anesthesia, and honest advice on timing. Paw Priority, 8020 Melrose Ave.
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