BOG SPAVIN

Bog spavin refers to a chronic synovitis of the talocrural joint characterized by distention of the joint capsule.

Faulty conformation may lead to weakness of the hock joint and increased production of synovia. In such cases, both limbs are affected .

The joint becomes distended by excess synovial fluid and/or thickened synovial tissue bringing about a soft, fluctuant swelling on the front of the joint, as well as in the medial and lateral plantar pouches

Causes

Causes include synovitis (inflammation of the lining of the joint capsule),degenerative joint disease, or excessive strain of the joint capsule.

In horses younger than the age of three, most cases of bog spavin are caused by a defect in the tibiotarsal joint, while in older, fully mature horses, it is most likely because of chronic strain of the joint capsule.

Infection of the joint causes a severe synovitis, and should be treated as an emergency.

The horse usually is not lame unless the condition is complicated by additional bone and cartilage involvement.

The primary distention of the joint capsule occurs on the dorsal medial surface of the hock, while smaller swellings develop on each side of the proximal caudal aspect.

The distention may spontaneously appear and disappear in weanlings and yearlings.

The excess fluid within the joint capsule may be aspirated; however, this is only of temporary benefit, as the distended joint space is rapidly refilled by synovial fluid.

Through external bandage support or the application of a commercial boot for several weeks, the stretched joint capsule slowly reverts to normal size.

injection of intra-articular corticosteroids provides variable and transient relief and is best applied in conjunction with rest and external support.

The injection may be repeated 3 wk later if necessary.

Arthroscopy should be performed when osteochondral involvement is suspected.

Bog spavin tends to recur, especially if poor conformation is an inciting factor.

References

The Merck Veterinary manuals