Catastrophic Wounds and Treatments
Two novel methods of wound treatment were used on five valuable American Saddlebreds attacked and injected with an unknown caustic substance in the back of their left front pasterns on June 30. The tissue in the injected area became necrotic (died), leaving painful, difficult-to-treat lesions that has resulted in death of two of the horses. The attackers of the horses based near Lexington, Ky., have not been apprehended despite a $100,000 reward.
The first treatment used by veterinarians in these cases was Lacerum, a topical solution including equine platelets, which are cells that assist in blood clotting. The platelets are harvested from whole blood drawn from disease-free members of a United States Department of Agriculture-approved equine herd (an alternate BeluMedX product called Lacerum A is derived from the injured horse's blood). The platelets are then concentrated and put in 10-mL single-dose vials that are frozen and sent to veterinarians, who thaw and activate the platelets with a biologically prescribed material including thrombin, an enzyme involved in clotting. The resulting "gel" is applied to a dressing for the wound after the wound is washed with a special solution.
Dennis Hendren, president of BeluMedX, said, "The activation (of the platelets) creates a soft scab, or a gelatinous material, which is an extra-cellular matrix…basically a scaffolding that can be put into the wound bed. In addition, the platelets release naturally occurring proteins ("growth factors") that stimulate and regenerate all types of tissue (bone, tendon, skin, hair, etc.). In addition, the scaffolding not only allows the stimulated cells to grow out (to the level of the skin), but also allows for the recruitment of surrounding cells to come in (and cover the wound)."
A Lacerum treatment study published in Experimental and Molecular Pathology in June noted improved organization of skin cells and proteins in healing wounds in deeper skin layers compared to untreated wounds. The resulting tissue was more similar to undamaged skin than the more disorganized, often weaker, tissue that forms over large, untreated wounds.
An over-the-counter product, Eclipse, made with the released protein is available from the company as well.
Charles E. Worden, Sr. developed the successful human precursor to Lacerum several years ago while working in human research. Later, he and Dennis Hendren founded a company dedicated to helping diabetes patients heal chronic wounds in their extremities. Mr. Worden was granted a patent from the United States Patent Office for this technology in October of 2001. As an avid horse breeder and owner, Worden had a special interest in helping horses with similar wound problems, even cases in which euthanasia was recommended.
"Not only can we regenerate tissue, we've learned that we can reduce the amount of inflammation" And, we know that the length of time of inflammation contributes to the amount of scarring. By doing all these things in a synergistic manner, we're actually reducing the potential for the scar outcome," said Worden.
"The overall goal is to give the animal a chance to be functional and assume the role it had been in prior to the injury," added Hendren. "That it has a good cosmetic outcome is just a side benefit to the technology that we've brought across to the treatment of these animals.
BeluMedX states that yet another beneficial effect of the Lacerum is pain relief; Horses under Lacerum treatment become more manageable during wound care.
Lacerum's dramatic effects have caught the attention of some Thoroughbred owners whose horses have been given grim prognoses for injuries. Dr. David Jolly, owner of A Step Ahead Thoroughbred Training Center in Hot Springs, Ark., has been testing Lacerum at his facility for the last 2 1/2 years, and many of his patients have been Thoroughbreds. He's currently up to his 73rd case—he documents the healing progress of each one on video.
Jolly gave examples of some of his cases. "Four of the horses that I've treated have come back and run—one mare came walking out of the field with a piece of barbed wire in her rear leg and a partially severed tendon. (After growth factor treatment) she ended up winning two races about six months later, when all we were really trying to do was rehabilitate her as a broodmare."
He recalled a horse which suffered injuries from a dumpster at Prairie Meadows and tore the muscles in his shoulder, leaving a dramatic, deep incision line. Jolly ran a 22-inch tube up from the bottom to the top of the wound, then squirted and packed Lacerum in to the deepest part of the injury. It healed up nicely and the horse won a race (which one?) a few weeks ago.
The Thoroughbred mare Annie's Sister Ida had a similar experience with a trailer injury and her case study can be seen on BeluMedX's web site, www.belumedx.com/vets/study2.htm. Before and after pictures are graphic, but show the dramatic results of growth factor.
Jolly emphasized the importance of keeping horses moving around some during treatment. "With training as your rehabilitation instead of immobility, when you put the horse outside and start real exercise, you won't end up with a horse that pulls adhesions apart and can't do anything," he explained.
With treatment experience came insight on how to make the outcome even better with management. If Jolly feels that he's not getting adequate wound cover with the gel, he might use antibiotics for a few days (he's generally moved away from heavy antibiotic use because of the difficulty in keeping the antibiotic in injured extremities). With the use of an occlusive bandage (one that doesn't let anything in or out), He says that he can leave each Lacerum treatment on for three to four days. Additionally, he has found novel ways to keep the bandage in place--and the Lacerum squarely on the wound. Jolly believes that, especially in hock wounds, pantyhose and Velcro are inexpensive, effective tools that can be used in bandaging these difficult-to-treat areas.
Hendren, Jolly, and Worden hope that veterinarians all over the country might want to begin their own studies using Lacerum. "We're attempting to bring a technology that will give a consistent result and ‘within a period of time, you can expect to see a wound look like this,' " said Hendren.
Jolly added, "We are giving the veterinary profession a new tool that may allow them to treat catastrophic wounds so that the horse owner can afford it and appreciate the result."
The second treatment used on the horses was ACell Vet, a medical device derived from the urinary bladder of specially bred pigs (called SPF, or specific pathogen-free pigs). The product is a biologic scaffold that promotes remodeling of damaged or injured tissue. The technology behind this naturally occurring "extracellular matrix (ECM) scaffolding" is the result of over 15 years of research at a number of academic institutions. ACell, Inc. holds the patents issued for this specific extracellular matrix.
Ralph Leasure, executive vice president of sales with ACell, said, "Research shows that these extracellular matrices act as a scaffold around which new cells populate and differentiate in a process called constructive remodeling," Leasure explained. "The new tissues are functional and act just like the normal tissue."
ACell is a xenograft material, meaning it's a surgical graft of tissue (in this case, porcine bladder) from one species onto or into individuals of an unlike species. The reason why the body does not reject the xenograft is because all cellular material has been removed leaving only the acellular matrix, an ideal material on which new tissue can grow. The body's acceptance of the tissue is "similar to why a woman doesn't reject the tissue of her unborn child. It's a foreign tissue, but it's accommodated," Leasure explained.
How It's Used
The product comes either as a hydrated sheet or a freeze-dried sheet. Leasure said the freeze-dried product is easier to work with and comes in a 10x7cm (roughly 3.9 x 2.7 inches, in its largest size) sheet that looks like parchment paper, and is approximately 80 microns (approximately 0.003 inches) thick. "The ECM consists of a collection of proteins that are arranged in a three-dimensional ultrastructure that is impossible to replicate in the laboratory," said literature on ACell's web site (www.acell.com).
Any dead tissue, eschar (dry scab that forms on skin that has been burned or exposed to corrosive agents), scarring around the edge of the wound, or flesh with foreign bodies embedded (like dirt or gravel) must be debrided before application of the product.
Generally, the product is applied with a saline-soaked gauze overtop and held in place with a light wrap. "In areas where it's tough to bandage, it's sometimes sutured in place," he explained. After the scaffold is implanted in a site, multi-potential cells populate the matrix and new blood vessels begin to form. Upon seeing normal stress, the cells differentiate into site appropriate tissue.
"In a wound care situation, most of the time within three to five days (the product) is totally incorporated," said Leasure. "What replaces it are new cells and new blood vessels as the body is trying to make new tissue with its own genetic code. Eventually the product is totally resorbed." New pieces of ACell Vet should be applied (over the prior one) every 3-4 days for the first 10-12 days. According to company literature, most wounds require 2-4 treatments, and larger wounds will typically take longer to heal and may need longer treatment.
In pre-clinical trials, the ECM scaffold has shown the ability to form new esophageal tissue, urinary bladder, vocal cord and laryngeal tissue, skeletal muscle and body wall, heart valves, and even new myocardium (a type of heart tissue).
Leasure said that ACell Vet product has many equine athletes, and case studies can be viewed at www.acell.com/vetcasestudies.html. In a notable case, a Thoroughbred racehorse with chronic run-down injuries returned successfully to the winners circle after treatment with ACell Vet.
He also gave a recent example of a case involving a horse that stuck its foot through an airline crate during transport and suffered a severe cannon bone degloving injury. "It forms new tissue unbelievably‹in degloving injuries it has regrown tissue and even hair in areas where the hair follicles have been removed."
Another application of ACell Vet that has drawn veterinary interest is the treatment of corneal ulcers. Novel applications for tendon and ligament injuries are also currently being researched.
"The exciting thing about ACell Vet is that it naturally provides the framework for the body to heal itself, or as we say, "Better healing…naturally," Leasure concluded.
About the Author
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.
POLL: University Equine Hospitals