Osteochondritis dissecans

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

Osteochondritis Dissecans

Osteochondritis dissecans (OCD) is a common type of developmental orthopedic disease (DOD) that affects the cartilage and bone in the joints of horses. It is caused by a failure of the endochondral ossification in epiphyseal plates and joint cartilage. In horses with OCD, the joint cartilage doesn't form normally, causing the underlying cartilage and bone to thicken and weaken. This can lead to the development of cartilage and bone flaps which remain partially attached to the bone or break off and disperse throughout the joint. The presence of these loose flaps and areas of abnormal cartilage and bone cause inflammation of the joint, which over several years can increase the likelihood and shorten the age of onset of arthritis. The joints most commonly affected by OCD in horses include the hock, stifle and fetlock joints.

OCD and Subchondral bone cysts are commonly considered to be manifestations of Osteochondrosis (OC). 5-25% of horses develop clinical signs of disease resulting from OCD. When clinical signs do develop, they can be seen as early as 5 months of age, but often may not occur until the horse begins work. At that time, the most common presentation is the onset of swelling in the joint, and varying degrees of lameness. Many horses with OCD are sound at the walk but show signs of lameness at faster gaits or when they begin work.

Symptoms

Effusion (swelling) in the joint
Lameness
Stiff gait

Diagnosis

  • History
  • Clinical signs
  • Physical exam
  • Radiographs - Since OCD is often bilateral, radiographs of the opposite joint are usually indicated, even if there is little to no swelling present in that joint.
  • Lameness exam
  • Ultrasound

Treatment


TreatmentDetails
ArthroscopySurgical removal of the abnormal bone and cartilage by making two or more small (less than 1 cm) incisions into the joint through the use of an arthroscope (a tiny camera) and other special instruments. This procedure is performed by an ACVS board-certified veterinary surgeon. It is preferred over another type of surgery called an arthrotomy, which requires surgeons to make a large incision into the joint which results in more surgical trauma and risk.
ArthrotomyAnother type of surgical procedure used for removal of OCD fragments, however it is done through surgeons making a large incision into the joint, as opposed to small incisions as conducted in an arthroscopy.

Prevention

  • Provide young horses with appropriate mineral supplementation.
  • Young horses should have restricted exercise and a reduced diet to slow growth rate.

Prognosis

Good to excellent if recognized early and treated surgically

Scientific Research References

Good Overviews

Risk Factors

  • Nutrition : High-energy or low copper diets
  • Rapid growth and large body size
  • Trauma and exercise: acute or recurring trauma and even routine exercise is frequently associated with the formation and loosening of the OCD flap.
  • Genetic predisposition
  • Hormonal imbalances: Insulin and thyroid hormones