Equine Lameness for the Layman. G. Robert Grisel, DVM
Upward Fixation of the Patella (IUPF): A condition characterized by inadvertent engagement (or locking) of the patella over the medial trochlear ridge of the femur (an action epitomizing the primary component of the hind stay apparatus).
Intermuscular: Between muscle bellies.
Interphalangeal: Between two phalanges.
The horse has three phalanges in each limb: the first phalanx (also known as the long pastern bone or P1), the second phalanx (also known as the short pastern bone or P2), and the third phalanx (also known as the coffin bone, pedal bone, or P3). There are two interphalangeal spaces: one between P1 and P2 and one between P2 and P3.
Intra-: Within.
Intramuscular: Within a single muscle belly.
Intrinsic: Originating from within the horse’s body or respective body part.
Ipsilateral: Located on the same side of the horse. “The right front limb is ipsilateral to the right hind limb.”
J
Joint: A point of articulation between two or more bones. Joints serve to absorb the force of impact, transfer the force via cartilage to bone, and to allow a variable degree of movement between bones.
K
Kinematics: The geometry of movement.
Kinesiology: The science of movement.
Kinetics: Forces that cause movement.
Kyphosis: Excessive ventroflexion of the spine, often referred to as a roached back.
L
Laminitis: Inflammation of the (laminar) tissues that bond the horse’s hoof to the underlying (pedal) bone. Laminitis is often bilateral and more commonly associated with the horse’s forelimbs.
Lateral: Away from the median plane. “When you look at a horse’s left side you see the lateral surfaces of the left limbs.”
Lateral Gait: A method of movement in which the forelimb and hind limb situated on the same side of the horse mimic each other in action.
Laterality: Dominance of one side of the brain or body over the other side.
Lead: The forelimb not assigned to the working diagonal pair determines the lead at the canter, gallop, and run. The lead forelimb protracts farther than the other forelimb at these gaits.
Ligament: A band of fibrous connective tissue that attaches bone to bone or bone to tendon. Ligaments serve to stabilize structures relative to one another.
Lordosis: Excessive dorsiflexion (or extension) of the spine, often referred to as a swayback.
Luxated: Full dislocation or displacement of one object relative to another. This term usually refers to the abnormal positioning of bones relative to one another across a joint.
M
Medial: Toward the median plane. “When you look at a horse’s left side you see the medial surfaces of the right limbs.”
Median Anatomy: Parts of the horse’s body that are located near to or along the median plane (or midline).
Median Movement: Motion associated with the horse’s axial anatomy comprising the head, neck, chest, abdomen, rump, and tail (everything excluding the limbs).
Median Plane: Divides the horse’s body into right and left halves.
Metricity of Stride: Refers to the degree of movement with respect to the horse’s stride.
Midline: An imaginary line that splits the horse into right and left halves (see also Centerline).
Motor Nerves: Nerves that serve to incite muscle contraction or gland activity.
Multifactorial Lameness: Altered movement arising from more than primary source of pathology. “A horse with current right front foot and right stifle joint pain would be expected to exhibit multifactorial lameness.”
Muscle: Tissue comprised of fibers that have the ability to contract and relax, thereby generating movement or maintaining posture of the bones to which it is attached.
Musculoskeletal: Refers to the horse’s bones, muscles, ligaments, tendons, and joints.
Myopathy: Muscle disease.
Myositis: Inflammation of muscle tissue.
N
Natural Gait: A gait that the horse demonstrates within the first few days of life and is not inspired by generations of breeding.
Negative Palmar/Plantar Angulation: Abnormal positioning (angulation) of the third phalanx (P3, coffin, or pedal bone) within the hoof capsule; the front of the bone is elevated relative to the back of the bone and ground surface.
Neurologic Lameness: Altered movement(s) made in response to a lack of neuromuscular input and/or in an attempt to maintain balance.
Neuropathy: A disease or condition affecting the nervous system.
O
Off Side: The horse’s right side, also known as the far side.
On Side: The horse’s left side, also known as the near side.
Oscillation: The repetitive up-and-down movement of one or more of the horse’s body parts.
Ossification: The process of assuming the characteristics of bone. Sometimes denoted as calcification.
Overreaching: Striking of a forelimb with the ipsilateral hind limb (on the same side of the horse). Usually occurs as the toe of the hind foot strikes the heel of the ipsilateral forefoot at the trot. Also known as forging.
P
Pain-Mediated Lameness: Altered movement(s) made in an attempt to avoid pain. Pain is invariably a consequence of local inflammation and/or nerve compression. As you might surmise, pain-mediated lameness hurts.
Palmar: Toward the back of the forelimb below the level of the carpus. “The navicular bone sits palmar to the coffin joint.”
Palmarolateral: Toward the back and outside of the forelimb below the level of the carpus. “The outside proximal sesamoid bone is positioned palmarolateral to the fetlock joint.”
Palmaromedial: Toward the back and inside of the forelimb below the level of the carpus. “The inside proximal sesamoid bone is positioned palmaromedial to the fetlock joint.”
Palpation: The examiner’s use of fingers and hands to physically perceive abnormality(ies) on or within the horse’s body and limbs.
Pathognomonic: Distinctively peculiar to a specific disease