Thornton, CO Animal Ordinances: Pet Limits (2026)

Section 6-37(a) makes it unlawful to harbor or allow more than a combined total of four dogs, four cats, or a mix of dogs and cats totaling no more than four, or one Vietnamese potbellied pig, per residential dwelling unit. If dogs, cats, and a pig are harbored together, the cap tightens to only three dogs or three cats plus the one pig. The limit does not count puppies or kittens under three months old from the same litter of a female dog or cat kept at the unit, so a new litter will not immediately put an owner over the cap.

The section does not apply to animals kept in an agricultural district under uses approved in compliance with Chapter 18, and miniature goats permitted under Section 6-54 separately count toward this same four-animal cap when combined with dogs, cats, or pigs at the same dwelling. The pet limit is enforced apart from, and in addition to, the general prohibition on other livestock and fowl in residential districts found in Section 6-36(a).