San Mateo County, CA Animal Ordinances: Mandatory Spay/Neuter (2026)
Key Facts
- Governing section
- § 6.12.020(a)
- Age trigger
- Cats/dogs over 6 months
- Alternative to altering
- Unaltered-animal or breeding license
- First-offense fine
- Up to $100 (§ 6.12.060)
Summary
Cats and dogs over six months old in unincorporated San Mateo County must be spayed or neutered unless the owner instead obtains an unaltered-animal license or breeding permit under § 6.12.020.
Any person who owns or harbors within the unincorporated San Mateo County, any cat or dog over the age of six months which has not been spayed or neutered, shall procure either a license to keep an unaltered dog or cat or a license and permit for breeding cats or dogs issued by the San Mateo County Animal Control Program under section 6.12.030 of this chapter.
Official source re-checked September 7, 2026: no newer edition of the code had been published (publisher’s edition: Code of Ordinances: Supplement 47).
Full Breakdown
County Ordinance Code § 6.12.020(a) requires any person who owns or harbors a cat or dog over six months old in unincorporated San Mateo County to procure either a license to keep an unaltered dog or cat, or a breeding permit under § 6.12.030, so the animal must be altered unless the owner secures one of those two licenses. Anyone providing care for 30 or more days is deemed the owner and subject to the rule, though registered barn-cat and feral-cat colony caretakers under § 6.12.020(d) are exempt from that ownership presumption.
Violations & Fines
Keeping an unaltered, unlicensed cat or dog violates Chapter 6.12 and is an infraction: up to $100 for a first offense, $200 for a second within a year, and $500 for each additional violation (§ 6.12.060).
Frequently Asked Questions
Do I have to spay or neuter my dog in San Mateo County?
Are feral cat caretakers required to alter every cat?
Sources & Official References
Other rules in San Mateo County
California rules heatmap·Compare San Mateo County to another location·View the California animal ordinances overview
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