A catch all phrase used to describe a range of conditions affecting the musculoskeletal system of growing foals. It involves all breeds of horse with one study in 2008 estimating an overall incidence of 66% of 392 foals from 21 stud farms being affected and warmblood foals having the highest incidence.
D.O.D. encompasses various conditions including:
- Osteochondrosis OC (a.k.a. Osteochondrosis Dissecans OCD)
- Bone cysts (subchondral bone cysts)
- Angular Limb Deformities (bent legs)
- Flexor deformities (Contracted Tendons)
- Cervical Vertebral malformation (a.k.a. Wobbler Syndrome)
- Cuboidal Bone (Tarsal Bone) Collapse
Whilst the conditions primarily affect growing foals the manifestations may persist into later life.
Broadly speaking D.O.D. involves disturbance to the normal maturation of cartilage, including the cartilage in growth plates, and its conversion into bone. The cause is multifactorial and may involve:
- Genetic predisposition
- Hormones (Insulin & Insulin Resistance)
- Nutrition & dietary factors
- Trauma and biomechanical stresses
- High or excessive growth rate / growth spurts
Some conditions may be present at birth (e.g., OCD) but generally signs appear at different times according to the condition involved, ranging from 1-4 months age for flexural limb deformities up until 2 years old or more for Cervical Vertebral Malformation (Wobblers). Individual foals may be affected by more than one of the above conditions or have multiple lesions in different places.
Space does not permit a more detailed review but despite the large number of foals afflicted by D.O.D. it should be noted that many will self-correct without treatment and only a relatively small percentage require intervention.