A simple strain or overstretch of the tendon sheath can cause a sudden onset inflammation and lameness. This condition, known as tenosynovitis, usually responds fully to anti-inflammatory therapy including a steroid injection, hyonate injections, topical Compagel and rest followed by a controlled exercise program. However, tendon sheath effusions can be driven by an injury within the structure and these do not always respond fully to conservative treatment, or can recur. For this reason an ultrasound scan is performed prior to a steroid injection, there are three main structures that can be affected:
A tear of the superficial or deep digital flexor tendon within the sheath may cause recurrent swelling and lameness that does not respond fully to medical treatment. Surgical investigation of the sheath with an arthroscope may be required to accurately diagnose and treat tendon injuries.
The annular ligament runs horizontally across the upper margin of the tendon sheath, it prevents swelling within the sheath extending upwards, this restriction can cause the tendon sheath inflammation to be firm and painful. It is not a vital structure and may be cut as part of surgical management of the condition.
The Manica Flexoria is a collar of tendinous tissue; it extends from the superficial digital flexor tendon and wraps around the deep digital flexor tendon. Cobs are prone to injuring the structure which, as with the annular ligament, may require excision if it is causing recurrent lameness.
In summary, windgalls that are soft and have slight variations in size according to your horses’ management are usually nothing to worry about but a firm swelling with lameness should be investigated.