Equine Lameness for the Layman. G. Robert Grisel, DVM
A disease process or the study of disease. Anything that is pathologic is abnormal.
Peak Vertical Force (PVF): The maximum vertical ground reaction force, which is encountered by each limb during mid-stance.
Pennate: A pattern of muscle tissue in which individual fiber bundles (called fascicles) attach obliquely (in a slanting array) to a common centralized tendon that runs the entire length of the structure. This pattern allows for higher force production but maintains a smaller range of motion.
Perineural: Near or adjacent to nerves.
Periosteum: A dense layer of connective tissue that covers bone.
Peripheral Lameness: Lameness associated with the horse’s extremities (limbs).
Peripheral Neurologic Lameness: Altered movement stemming from abnormal function of nerves outside of the brain and spinal column.
Periphery: The aspects of the horse located away from the center or midline. “The peripheral nervous system comprises the nerves and ganglia outside of the brain and spinal cord.”
Pisos: A term describing the quality of gait (e.g. timing, extension, animation, smoothness, elegance, and forward motion) demonstrated by the Peruvian Paso horse.
Plaiting: Technically means braiding. With respect to equine ambulation, plaiting refers to the way in which the limbs track during protraction; one foot is placed directly in front of the other. Often referred to as rope walking.
Plantar: Toward the back of the hind limb below the level of the tarsus. “The hind navicular bone sits plantar to the coffin joint.”
Plantarolateral: Toward the back and outside of the hind limb below the level of the tarsus. “The outside proximal sesamoid bone is positioned plantarolateral to the hind fetlock joint.”
Plantaromedial: Toward the back and inside of the hind limb below the level of the tarsus. “The inside proximal sesamoid bone is positioned plantaromedial to the hind fetlock joint.”
Posterior: Toward the rear of the horse. More appropriately denoted as caudal. “The horse’s pelvis is posterior to the withers.”
Prognosis: A forecast of the course of a disease or affliction. “High-motion joint disease often carries a guarded prognosis for future soundness in the performance horse.”
Protraction: The movement of a body part (e.g. a limb) in a forward direction.
Proximal: Toward the attached (upper) end of the limb. “The carpus is proximal to the fetlock joint.”
R
Retinaculum: A fibrous retaining band that houses and stabilizes multiple tendons as they course along the horse’s limb.
Rostral: Toward the nose. Refers only to anatomy of the head. “The horse’s eyes are rostral to the ears.”
S
Sagittal Plane: Any plane parallel to the median plane. For instance, a plane dividing the right and left sides of a hoof.
Sensory Nerves: Nerves that serve to carry sensory information to the brain for processing.
Sheath: A “sleeve” that envelops tendons as they course over or under joint surfaces.
Solar Surface: The (bottom) aspect of the foot that contacts the ground surface.
Speedy Cutting: Striking the hind limb with a forefoot. Usually observed in disciplines that entail making sharp turns at high speeds (e.g. barrel racing and cutting).
Stance: The phase of a horse’s stride during which the respective limb is in contact with the ground surface.
Stay-Apparatus: An arrangement of muscles, tendons, and ligaments that work together to “lock” major joints of a limb in the extended position. The horse enjoys stay-apparatuses in both the fore and hind limbs, thereby allowing it to remain standing with minimal muscular effort. The mechanism is transiently employed during locomotion and fully employed during periods of upright sleep.
Striking: Contacting a limb with a hoof.
Subacute: Of fairly recent onset. “This is a subacute lameness; it developed last Tuesday.”
Subluxated: Partial dislocation or displacement of one object (usually bone) relative to another.
Suspensory Desmitis: Inflammation of the suspensory ligament body and/or its branches.
Synarthrodial Joint: A fibrous junction that allows little or no motion between articulating bones.
Syndesmodic Joint: An immovable joint in which bones are joined by dense connective tissue.
Synovial: Associated with a joint, tendon sheath, and/or bursa (which are all synovial structures).
T
Telemedical Evaluation: Remote analysis performed through the use of telecommunications technology (e.g. electronic devices such as smart phones and computers).
Tendon: A band of fibrous collagen tissue that attaches muscle to bone. Tendons serve to move structures relative to one another.
Tendon Sheath: A “sleeve” that facilitates tendon movement over or under joint surfaces via synovial lubrication.
Tendonitis: Inflammation of tendon tissue.
Tenobursitis: Inflammation of tendon tissue within the confines of a synovial bursa.
Tenopathy: Tendon disease.
Termino: A desirable action in the Peruvian Paso horse; outward swinging of the forelimb that emanates from the shoulder joint.
Thread: The character of transitions demonstrated by the Peruvian Paso horse from the walk up and through the faster gaits.
Torsion: Twisting or wrenching of the horse’s body or body part.
Transverse Plane: Passes through the head, body, or limb perpendicular to the part’s long axis.
U
Unilateral Lameness: Altered movement manifesting on one (either right or left) side of the horse, but not both.
V
Ventral: Toward the lower aspect (bottom) aspect of the head, neck, belly, and pelvis. Does not refer to the horse’s limbs. “The horse’s sternum is ventral to the withers.”
Ventroflexion: Bending of the spine in a way that moves either end toward the ground surface.
W
Winging-In: The foreleg swings to the inside (toward the horse’s midline) during protraction. Also known as dishing.
Winging-Out: The foreleg swings to the outside (away from