San Mateo County, CA Animal Ordinances: Pet Limits (2026)

Section 6.20.020(a) sets the unincorporated county's baseline: keeping five or more dogs, five or more cats, or five or more dogs and cats in any combination at one dwelling unit or business establishment is unlawful unless the keeper conforms to the rest of Chapter 6.20, Kennels and Catteries. Section 6.20.010 fixes how the count is taken: every animal over four months old counts, and so does any animal that has received care and sustenance for 30 days or longer, so a long-term foster or a litter that has aged past four months pushes a household over the line even without a formal adoption.

Two permit tiers apply above that threshold. An "animal fancier," defined in Section 6.20.010(b)(1) as someone keeping 5 to 10 dogs, 5 to 10 cats, or a combination totaling 5 to 10, needs an animal fanciers' permit under Section 6.20.030 and may locate only in zoning districts where the County Zoning Regulations allow that use. Anyone keeping more than ten dogs, more than ten cats, or more than ten combined, meets the "kennel" or "cattery" definition in Section 6.20.010(b)(2)-(3) and needs a full kennel/cattery permit under Sections 6.20.040 through 6.20.070, which requires a Planning and Building Division application, a 300-foot notice to neighboring property owners, an environmental information form, and Zoning Hearing Officer findings on sanitation, animal welfare, and neighborhood compatibility. Section 6.20.020(b) exempts research and teaching animals, seeing-eye and service or working dogs, licensed veterinary hospitals, and licensed pet-sale or grooming establishments from the fancier and kennel/cattery permit requirement.