I found this:
These are for Saint Mary's County : Planning and Zoning Faq ( Linky )
Quote:
FAQ #6: How many animals may I have on my property?
Our zoning ordinance does not regulate the number of animals kept for agricultural activities.
However, animal husbandry operations must maintain adequate fencing or other means of confinement (CZO Section 51.3.3.a).
Animals kept for personal enjoyment are not regulated by the zoning ordinance except when shelter is provided for hoofed animals. A stable requires at least three acres of land.
If a stable is provided, two “large animals” per acre are permitted (CZO Section 51.3.118). “Large animal” is not defined.
Quote:
FAQ #18: Can I have a horse on my property?
Horses are regulated by our zoning ordinance only with respect to their shelter. A private stable is described as an accessory structure, not related to the ordinary operation of a farm, for housing hoofed animals (CZO Schedule 50.4 Use Type 118).
A private stable is a permitted accessory use in the RPD, RSC, RNC, VMX, and TMX zoning districts (same reference as above).
A minimum lot size of 3 acres is required. The stable must be located at least 100 feet from side or rear lot lines. Two “large animals” per acre of land are permitted
(CZO Section 51.3.118).
Therefore, one may have a horse anywhere in the county unless they want to provide it with shelter. Stabling triggers the above zoning restrictions.
My understanding is that minis are not considered "large" animals.