A medical device derived from the lining of urinary bladders of specially bred pigs shows promise for healing equine tendon and ligament injuries, according to Rick Mitchell, DVM, of Fairfield Equine Associates in Newtown, Conn. Mitchell recently addressed a group of veterinarians at Emerald Downs in Auburn, Wash., about the technology and his positive experiences with it in his practice.

Urinary bladder matrix (UBM), sold under the name ACell Vet, is a naturally occurring extracellular matrix scaffolding that promotes remodeling of damaged or injured tissue. It does this by recruiting cells for tissue differentiation from the circulatory system and local tissues (click here for more on ACell Vet and its use on catastrophic wounds). It’s typically distributed as a thin, dehydrated or hydrated membrane. ACell scientists approached Mitchell and other veterinarians to determine if there might be an application of the UBM technology for equine ligament and tendon injuries. Since tendon and ligament tissue structures are dense, it was thought that powdered UBM material in suspension could be injected into these structures without seeping out of them.

Mitchell’s clinic treats predominantly jumpers and some dressage horses, and he has been using the UBM treatments for about 11⁄2 years. He explained, “The positions (these horses) get themselves in performing dressage and landing awkwardly off a wide jump can certainly (put them) in some rather stressful positions with a full weight bearing of a 1,200-1,500-pound frame on one limb, and so the opportunity for injury there is great.”

Mitchell said that before any horse was selected for the UBM treatment in his clinic, he firmly established a diagnosis through full lameness workups, diagnostic nerve blocks, and sometimes nuclear scintigraphy and diagnostic radiographs. “Most of the horses I have done this procedure on have been horses that failed to respond to corticosteroid infiltration, shock wave therapy, rest, laser, ultrasound—you name it, they’ve been to us,” he said. He had used UBM as a first course of treatment on a few fresh, very severe cases.

After suspending the UBM in saline, Mitchell uses a surgical procedure identical to that which is used to administer bone marrow (see article #4755 online).

Prior to Oct. 12, 2003, Mitchell’s practice had performed 31 proximal suspensory injections, many in combination with a fasciotomy, or an incision through the muscle fascia that is performed when swelling is anticipated that could compromise blood flow, cause pain, and constrict tendons and ligaments. They had completed three suspensory ligament branch injections and 10 superficial digital flexor tendon injections, for a total of 44 treatments. As of Oct. 12, 10 (22.8%) of the 44 horses were back to full working soundness, 17 (38.6%) were conditioning and sound, and 17 (38.6%) were convalescing. Mitchell added, “Eleven of 13 (84.6%) horses that were treated more than six months ago are in full work and are sound. That impresses me.”

Although it’s typically a one-time treatment, Mitchell had one problematic horse that required three treatments before improvement was noted.

He said that most horses which undergo UBM treatment have mild or moderate swelling, with a few developing severe swelling. Mitchell said the horse might be “mildly to severely lame for a few days--the typical horse is comfortable day one, sore day two and three, and better on day four and five. Some horses do become inordinately sore and remain so for upwards of two weeks.” He uses anti-inflammatories along with icing if necessary to help reduce the swelling.

Mitchell said he performs ultrasound exams 30 and 60 days post-treatment, with major results being evident on the second exam. He noted that measurements were still being performed on collected ultrasound images from the trials, but that “the fiber pattern speaks for itself,” showing that healthy tissue has formed.

He emphasized that traditional tendon/ligament injury therapies such as rest, support, anti-inflammatory therapy, ice, hydrotherapy, and poultices should not be abandoned, but used to reduce pain and swelling.

About the Author

Stephanie L. Church, Editor-in-Chief

Stephanie L. Church, Editor-in-Chief, received a B.A. in Journalism and Equestrian Studies from Averett College in Danville, Virginia. A Pony Club and 4-H graduate, her background is in eventing, and she is schooling her recently retired Thoroughbred racehorse, Happy, toward a career in that discipline. She also enjoys traveling, photography, cycling, and cooking in her free time.

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