A

      abscess: an infection around which the body has constructed a wall of
      fibrous tissue, to isolate it. Treatment with antibiotics is more likey to
      be effective if drainage of the abscess can be established, eliminating
      accumulated pus and debris.

     action: a horse’s manner of moving.

      acupressure: utilizing stimulation on acupuncture points to treat an
      animal.

      acupuncture: a centuries-old means of treating an animal or human through
      use of needles, electrical current, or moxibustion (heat and herbs) to
      stimulate or realign the body’s electrical fields.

      acute: referring to a disease: An acute disease is a disease of short,
      sharp course.

      age: many breeds, including Thoroughbreds and Quarter Horses, celebrate a
      common birthday on Jan 1.

      agent: a person empowered to transact business for a stable owner or
      jockey, or empowered to sell or buy horses for an owner or breeder.
     

      AHS: African Horse Sickness.

     all out: when a horse extends itself to the utmost.

      alternative therapy: a group of therapies (acupuncture, chiropractic,
      physical therapy, herbology, naturopathy) that help maintain the horse’s
      health and performance but without using medication.

      angular limb deformities: a limb that is crooked because of developmental
      problems in the angles of the joints. A problem of young horses, often
      present immediately after birth.

      anhydrosis: inability to sweat in response to work or an increase in body
      temperature. Also known as a "non-sweater." Athletic horses are affected
      most frequently, though the condition also appears in pastured horses that
      are not being ridden. Most commonly occurs when both temperature and
      humidity are high. Horses raised in temperate regions and then transported
      to hot climates are most prone to develop the condition, but even
      acclimated horses can be at risk. Clinical signs include inability to
      sweat, increased respiratory rate, elevated body temperature and decreased
      exercise tolerance. The condition can be reversed if the horse is moved to
      a more temperate climate.

     anterior enteritis: acute inflammation of the small intestine producing
      signs of abdominal distress such as colic and diarrhea.

     anterior: toward the front of the horse’s body.

     aortic rupture: bursting of the aorta (artery coming from the left
      ventricle of the heart that distributes blood to nearly all of the body).

      apical (fracture): see sesamoids.

     arthritis: inflammation of a joint. An increase in the amount of synovial
      fluid in the joint is a result of the inflammation. Accumulation of
      synovial fluid in the fetlock joint is called a "wind puff" or "wind
      gall." See also "green osselet."

     arthroscope: a tiny tube of lenses used for viewing areas inside a joint.
      Usually attached to a small video camera.

      arthroscopic surgery: surgery performed through the use of an arthroscope
      which eliminates the need to open the joint with a large incision in order
      to view the damaged area.

      articular cartilage: cartilage that covers the ends of bones where they
      meet in a joint.

      artificial breeding: includes artificial insemination or embryo transfer
      (transplant).

      arytenoid cartilages: triangular cartilages in the upper part of the
      entrance to the larynx. Movements of the arytenoids cartilages control the
      diameter of the laryngeal opening.

     ataxia: loss or failure of muscular coordination.

     atrophy: to waste away, usually used in describing muscles.

     avermectin: a class of dewormer products. The equine product ivermectin is
      a member of this class.