Abortion - When a dead embryo or is absorbed or expelled prior to the time when it could survive outside the uterus.
Abscess - A hole formed by dying tissue that is often filled with puss. A localized collection of pus surrounded by inflamed tissue.
Acre - Unit of measurement of land area; 4,840 square yards or 43,560 square feet.
Action - The horse's way of travel, how he moves his legs and degree of animation. The degree of flexion of the joints of the legs during movement; also reflected in head, neck, and tail carriage. High, snappy action is desired in some classes while easy, ground-covering action is the goal in other classes.
Afterbirth - Placenta, surrounds the foal in the uterus and transfers nutrients between
mare and foal. Also removes waste.
A.I. - Artificial insemination, the mechanical introduction of semen into the genital tract of the female.
Aid - An aid is an action by a part of the rider's or handler's body to a part of the horse's body to cause the horse to react in a particular way. An aid is almost never used alone but always used in conjunction with other aids. A rider's natural aids are his or her mind, seat, weight, upper body, legs, hands, and voice. The combined use of all of the rider's aids simultaneously produce a smooth, balanced response from a horse. A handler's natural aids are the mind, hands, and overall body language. Examples of Artificial Aids (which are extensions, reinforcements, or substitutions for the natural aids) are whips, spurs, and nosebands.
Aids - Signals from the rider to the horse with with his hands, seat, weight, legs and voice, to tell the horse what to do. . Natural aids are the mind, voice, hands, legs, and weight. Examples of artificial aids (which are extensions, reinforcements, or substitutions of the natural aids) are whips, spurs, nosebands, draw reins and martingales.
Alfalfa (medicago sativa) - A leguminous plant used primarily for hay, usually high in protein and calcium.
Amateur-Owner - Class open to horses whose owner or member of owner's immediate family is the rider.
Amateur - Rider over eighteen who does not get paid for riding. An individual who rides or exhibits a horse in competition, who does not derive profit from such activities and does not do so as a profession.
Amino acid - The main component of protein that the horse breaks proteins down to for absorption.
Anestrus - When a mare is not having or showing heat or estrus.
Antigen - Substance, often in protein form, that the body's immune system will react to
by producing antibodies.