Horses, quite literally, are bundles of nerves. Nerve damage and associated nerve pain can originate from numerous causes including degenerative diseases, inflammatory disorders, toxic reactions, trauma and other injury. When trying to diagnose nerve pain, it's important to differentiate between actual nerve pain and muscle weakness associated with nerve injury. Damaged nerves must regenerate from the point of injury to the terminus of the nerve in the muscle. For this reason, nerve injuries require rest and lengthy recovery periods. Good physical therapy programs directed veterinarians can help reduce muscle atrophy during recovery.
The Foot Has Feelings
Nerve pain in the lower limbs of a horse, particularly in a foot, is associated with a number of conditions, including laminitis and navicular disease. Your vet can perform a procedure called a nerve block, important for diagnosing foot and leg injuries, in which regional anesthesia, a numbing agent, is injected into specific nerves in your horse's foot or leg. While not entirely definitive, a nerve block helps pinpoint the source of a horse's foot pain. With lameness issues, the underlying cause must be treated along with any associated nerve pain.
Shouldering the Pain
Initially discovered in draft horses in the early 1900s, damage to the suprascapular nerve of the shoulder, often referred to as Sweeney shoulder, occurs today from blunt trauma to the shoulder, such as a horse receiving a kick from a pasture mate. Damage to the nerve prevents the muscles of the shoulder from moving the front leg forward. Muscles degenerate, making physical therapy important. Recuperation time for the rare condition can last between three and 12 months.
Bolstering the Back
Performance horses commonly experience back problems. Unfortunately, numerous factors make them difficult to diagnose. Often, diagnosis becomes more a process of elimination rather than immediate identification of the source of the pain. A system of nerves in the horse's back called nociceptive receptors may become irritated with trauma or stimulation. Factors contributing to nerve pain in a horse's back include ill-fitting tack, poor schooling, poor riding, a slipped disc, congenital defects and a tumor on the spinal nerve. Depending upon the cause, treatment normally includes administration of anti-inflammatory drugs such as phenylbutazone (Bute) or flunixin meglumine (Bantamine), combined with stall rest, physical therapy and acupuncture or chiropractic therapy.
The Head Shaker
Headshaking syndrome, defined as uncontrollable shaking or jerking of the head without any apparent reason, occurs more commonly in geldings. With an onset between 7 and 9 years of age, headshaking syndrome can occur seasonally or year-round. Photic head shaking, triggered by light, can normally resolve immediately when the horse is blindfolded or removed from sunlight. Trigeminal head shaking, occurring due to a hyper-reactive facial nerve, occurs when normal stimuli such as wind, touch or cold causes severe pain. Treatment involves reducing the stimuli causing the pain. While drug therapies exist, side effects such as lethargy and colic make them undesirable.