Severe masseter myonecrosis in a horse.

This study discusses the diagnosis and treatment of a horse suffering from severe masseter myonecrosis, a nutrition-related muscle condition, which successfully recovered after adequate medical care.

Study Details

In this study, a 6-year-old Quarter Horse experienced an extreme swelling of the masseter muscles, a condition diagnosed as masseter myonecrosis. This condition was recognized by a range of symptoms including:

• Pain upon palpation: When the swollen muscles were touched or examined, the horse showed signs of pain.
• Exophthalmos: This term describes a medical condition where the eyeballs are abnormally protruding from the eye sockets.
• Severe chemosis: Chemosis refers to the swelling of the conjunctiva, tissue that lines the inner part of the eyelids and covers the white part of the eyes.
• Protrusion of the third eyelids: The horse showed abnormal protrusion of its third eyelids, a transparent or translucent membrane in the eyes of some animals.

Diagnosis

To diagnose this condition, several tests were conducted which included:

• Blood selenium and vitamin E concentrations: These measurements were taken to understand if the horse may be suffering from nutritional deficiencies. Both selenium and vitamin E are crucial for the horse’s overall health and muscular performance.
• Feed analysis: An evaluation of the horse’s diet was done to understand if there were any nutritional gaps that might have led to this condition.
• Muscle biopsy: A small sample of the horse’s masseter muscle was taken to examine under the microscope. This helped in confirming the condition of nutritional myopathy.

Treatment & Post-Care

Based on the diagnosis of nutritional myopathy, the horse was treated accordingly. Post-treatment, the horse showed significant health improvements and was clinically normal 2 weeks after discharge from the hospital. This indicates that the horse responded well to the treatment, and the severe swelling and other symptoms were successfully managed.