Epiphysitis in Horses

Epiphysitis, also known as equine rickets, is a condition of the bones that occurs in horses and is recognized by a slight lameness in the animal. It usually affects the longer bones, occurring when joints, such as the knee joint, become enlarged. While there are several theories as to where this comes from, the most respected one is that it is caused by the overfeeding of young horses.

When a young horse is fed on a high plane of nutrition, or a high caloric diet, its metabolism becomes unbalanced, sometimes causing growth issues like rickets on the small body. In short, their bones grow too large or too quickly for the rest of their body. It is most commonly seen in Welsh Cobs and fillies that are preparing for an exhibition or show, and generally doesn’t affect every type of horse.

Symptoms and Types

• Pain in the joints

• Swelling in the joints

• Knee joint problems (e.g., knuckling of the knee joint, slight lameness)

• Knuckling of the fetlock (or the metacarpophalangeal and metatarsophalangeal joints)

• Abnormal contraction of flexor tendon (allowing the flexing of the joints)

• Abnormal contraction of cannon tendon (between the fetlock and the knee joints)

Causes

Horses on a high plane of nutrition, whether they be preparing for an athletic event or show, are more susceptible to rickets. Mineral and hormonal imbalances, especially brought on by overfeeding, can also lead to this condition.

Diagnosis

In order to diagnose epiphysitis, your veterinarian will probably need a great deal of information about your horse, including its medical history and nutritional information. What your horse has been fed is vital in determining the diagnosis.