Infection of the tendon sheath can be a life-threatening ailment, as it can be with any other infected synovial-lined structures such as joints or bursas. When bacteria are introduced into the sheath, usually due to a wound, they can proliferate quite readily due to the nutrient-rich synovial fluid, which provides an ideal environment for bacteria to thrive. Once the infection becomes established in the sheath, it can be particularly hard to eliminate as the bacteria can sit deep within the synovial lining or within fibrin strains and be protected from the normal body processes that remove foreign substances. Even by flushing the sheath with large amounts of fluids, the bacteria can remain lodged and protected and can continue to proliferate.
For this reason, many infected sheaths undergo tenoscopy as part of their treatment, allowing large areas of synovium and pockets of fibrin to be removed so the bacteria are exposed and can be physically removed in the process. Other methods of treatment include injecting medication directly into the sheath, using antibiotic infusion pumps or performing regional limb perfusion (RLP). RLP is a procedure whereby a tourniquet is applied to the limb, above the infected site, and antibiotic is injected into the vein below the tourniquet. The tourniquet effectively holds the blood in the region of the infection, allowing high concentrations of the antibiotic to penetrate the infected area and fight the infection. Often these procedures are required to be performed multiple times to overcome the infection and are performed in conjunction with prolonged administration of systemic antibiotics.
Following resolution of many of these tendon sheath infections in the limbs, the horse remains lame to some degree for many months afterward. The lameness usually responds to low doses of anti-inflammatory medication given periodically through this recovery, and then quite suddenly the lameness appears to resolve and the horse remains sound. Therefore, it is important to persevere with many of these lame horses once the infection has been cured, as they can become rideable again.
One of the complicating sequela of tenosynovitis, particularly in infectious cases, is the formation of adhesions and secondary thickenings of surrounding structures that restrict the smooth flow of the tendon through the sheath. Whilst these can be treated conservatively or medically, they often require further surgery to resolve the issue.
Although rare, there have been cases of tumours developing within tendon sheaths and these can usually be detected as an abnormality using ultrasonography or in difficult cases an MRI. A biopsy may be required to confirm the diagnosis and surgical removal of the tumour is usually necessary to resolve the inflammation. EQ
YOU MIGHT ALSO LIKE TO READ THE FOLLOWING BY DR MAXINE BRAIN:
The Mystery of Equine Shivers – Equestrian Life, July 2021
Heads up for the Big Chill – Equestrian Life, June 2021
The Ridden Horse Pain Ethogram – Equestrian Life, May 2021
The Benefits of Genetic Testing – Equestrian Life, April 2021
Heavy Metal Toxicities – Equestrian Life, March 2021
Euthanasia, the Toughest Decision – Equestrian Life, February 2021
How to Beat Heat Stress – Equestrian Life, January 2021
Medicinal Cannabis for Horses – Equestrian Life, December 2020
Foal Diarrhoea Part 2: Infectious Diarrhoea – Equestrian Life, November 2020
Foal Diarrhoea (Don’t Panic!) – Equestrian Life, October 2020
Urticaria Calls For Detective Work – Equestrian Life, September 2020
Winter’s Scourge, The Foot Abscess – Equestrian Life, August 2020
Core Strengthening & Balance Exercises – Equestrian Life, July 2020
The Principles of Rehabilitation – Equestrian Life, June 2020
When is Old, Too Old? – Equestrian Life, May 2020