Paralysis is the complete or partial loss of voluntary motor function in one or more muscle groups, resulting from disruption at any level of the motor pathway from the cerebral cortex through the spinal cord to the peripheral nerve and neuromuscular junction. In horses, paralysis is classified by anatomical distribution: monoplegia (one limb), hemiplegia (one side), paraplegia (both hindlimbs), and tetraplegia or quadriplegia (all four limbs). Common equine causes include equine protozoal myeloencephalitis (EPM) caused by Sarcocystis neurona, equine herpesvirus type 1 (EHV-1) myeloencephalopathy, cervical vertebral stenotic myelopathy (Wobbler syndrome), botulism affecting the neuromuscular junction, and peripheral nerve damage following trauma or injection site injury. Laryngeal hemiplegia, the partial paralysis of the left arytenoid cartilage caused by damage to the left recurrent laryngeal nerve, is among the most common neurological conditions in performance horses and produces the characteristic inspiratory noise known as roaring. Facial nerve paralysis can result from ill-fitting halters or head trauma. Diagnosis of the underlying cause requires neurological examination, cerebrospinal fluid analysis, serology, and imaging. Treatment depends on etiology; supportive care, physical therapy, and specific antiprotozoal treatment for EPM may be indicated. See also EHV-1 myeloencephalopathy, a viral cause of spinal cord damage and ataxia, and sudden collapse from sleep dysfunction for a non-paralytic differential with overlapping presentation.
Further Reading
- paralysis (Wikipedia)
- For clinical causes and management of equine limb paralysis: leg paralysis in horses — MSD Veterinary Manual