Fibrotic myopathy

Veterinary advice should be sought before applying any treatment or vaccine.

Fibrotic Myopathy

Ossifying Myopathy

Fibrotic myopathy is a mechanical lameness in horses, caused by restriction of the action of the horse's muscles. It occurs when horses injure their semitendinosus and semimembranosus muscles and can present in acute or chronic form.
Image of a typical horse with Fibrotic myopathy
It is frequently caused by performing abrupt turns and sliding stops. It can also be caused by IM injections, trauma, and due to a congenital form. The majority of horses with fibrotic myopathy had a previous history of trauma in the affected leg.

The associated gait abnormality is most obvious when the horse is walking or at a slow trot. The horse's leg appears to jerk suddenly to the ground rather than continue its forward motion.


Abnormal gait
Hindlimb lameness
Warmth and pain on deep palpation


  • History
  • Clinical signs
  • Physical exam
  • Ultrasonography
  • Thermography
  • Scintigraphy
  • Muscle biopsy



Rest and cold therapy
Ultrasound therapy
Controlled stretching
Anti-inflammatory therapy
Acuscope Myopulse
Surgery - laser fibrotomy combined with early post operative exercise, resection of scar tissue, semitendinosus myotenotomy


  • Warming up horses prior to exercise
  • Daily exercise or turnout
  • Limit intramuscular injections (and volume of substance to < 10ml) into the thigh muscles of athletic horses

Scientific Research

General Overviews

Risk Factors

  • Trauma
  • Abrupt turns
  • Sliding stops
  • Secondary to intramuscular injections
  • Abscess
  • Congenital