In ,
Rebecca McGraw wrote:

*
*I thought a mare was a female horse 4 years of age or older, regardless
*of whether or not she has foaled. Guess I have to go look it up.

Depends on where you're looking it up
The medical/physiological definition is that a filly turns into a mare at
sexual maturity - like a girl turns into a woman at puberty. But for
horses who are involved in different activities there may be different
definitions. A thoroughbred racehorse won't turn into a mare until she's
five. Go figure.

--
hillary israeli vmd http://www.hillary.net
"uber vaccae in quattuor partes divisum est."
not-so-newly minted veterinarian-at-large