Angular limb deformity refers to deviation of the limb from the normal axis. The limbs can either turn outward (valgus deformity) or turn inward (varus deformity). This condition can affect the knees, hocks, and fetlocks; however, the knees are most commonly affected.

Rhodococcus equi is a bacteria that lives in the soil. It is an important cause of disease in foals between 3 weeks and 6 months of age.