No One Wants a Lame Horse: The Positive Effects of Gene Therapy on Equine Osteoarthritis

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By: Whitney Stepp, Staff Member

Osteoarthritis (OA) is a degenerative and career-compromising disease in horses that is often emotionally and financially draining for owners. [i] OA a painful, incurable condition primarily characterized by the progressive destruction of articular cartilage[ii] and is also responsible for up to 60% of lameness in performance and pleasure horses.[iii] Equine lameness “is mild or severe loss of ability to move normally that can be caused by problems in a horse’s bones, muscles, nerves, tendons, ligaments, brains, circulation, and metabolism.”[iv] The majority of horse lameness problems occur in the foot,[v] which impairs their ability to do what they were in most cases purchased to do. Thus, it’s in a horse owner’s best interest to not only be aware of the symptoms of OA, but knowledgeable of the most effective treatments.

As with any medical diagnosis, progression of osteoarthritis can be slowed down with early corrective treatment.[vi] There are currently many symptomatic treatment options that veterinarians utilize to relieve clinical signs of Osteoarthritis, such as: prescription medications, icing, pressure wraps, exercise protocols, and dietary management to name a few.[vii] Unfortunately, while the current treatment options relieve clinical signs of OA, they have not been shown to prevent progression. [viii]

In a recent study, conducted by Dr. Ashlee Watts, DVM, an assistant professor at the Texas A & M College of Veterinary Medicine & Biomedical Sciences, a type of gene therapy, (using genes to treat or prevent disease), combined with mesenchymal stem cells, (MSC), was shown to reduce the progression of OA.[ix] The study consisted of thirteen mature Thoroughbreds in the early stages of experimentally induced OA, in all cases affecting the middle carpal bone that is located in knee.[x] Fourteen days after induction, seven horses received placebo injections to treat their OA, while the other six horses received the MSC and gene therapy injections in the affected joints.[xi] Dr. Watts admits that the process is complex, but in simple terms, she utilized gene therapy to augment stem cells to reduce destructive pathways in the joint and increase healing pathways.[xii]

The key results of the study revealed that there were no adverse effects of treatment with the combination of MSC and gene therapy. More importantly, in the week following treatment the researchers[xiii] observed significant improvements in range of motion and joint swelling in the joints treated, as compared to those that only received the placebo drug.[xiv] Also, the joints that were treated had reduced scarring on the joints and higher glycosaminoglycan levels that protect degenerating cartilage. Further, there was improved cartilage matrix gene expression, which is responsible for absorbing shock during weight bearing.[xv] Basically, the building/healing growth factor increased in production, improving soft tissue healing and reducing scar tissue formation, which in allows for more normal movement of the effected joints,[xvi] thus more activity for the injured horse.

Dr. Watts concluded that OA progression was significantly reduced in her model. [xvii] She also believes that “the stem cells may be the keep to major treatments without the gene therapy.”[xviii] It should be noted that further testing is needed in the area of gene therapy and equine clinical practices. With more experimentation and a potential third testing group that only received stem cells as opposed of the combination, researchers may discover major treatment improvements that lead to a complete stop in progression.

Essentially, the use of gene therapy is still in its infancy stages when it comes to clinical practices in equine medicine.[xix] However, more exploration into the possibilities for the use of gene therapy to treat equine injuries would be beneficial to horse owners in Kentucky and across the nation.
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[i] Blood-Horse Publications, Equine Osteoarthritis, Ask the Vet Live, (2014), www.thehorse.com/ask-the-vet/29970/equine-osteoarthritis .
[ii] Erica Larson, Gene Therapy, Stem Cells’ Effects on Equine Osteoarthritis, (Feb. 8, 2014), www.thehorse.com/articles/33350/gene-therapy-stem-cells-eefects-on-equine-osteoarthritis.
[iii] Vetoquinol, Equine Osteoarthritis, Osteoarthritis Fact Sheet, www.equistro.com (last visited February 15, 2014).
[iv] PetMed Express, What is Horse Lameness, (2014), www.1800petmeds.com/education/what-is-horse-lameness-52.htm.
[v] Id.
[vi] Vetoquinol, supra note iii.
[vii] Id.
[viii] Larson, supra note ii.
[ix] Id.
[x] Id.
[xi] Id.
[xii]Erica Larson, Gene Therapy, Stem Cells’ Effects on Equine Osteoarthritis, (Feb 11, 2014), www.farms.com.
[xiii] Id.
[xiv] Erica Larson, Gene Therapy, Stem Cells’ Effects on Equine Osteoarthritis, (Feb. 8, 2014), www.thehorse.com/articles/33350/gene-therapy-stem-cells-eefects-on-equine-osteoarthritis.
[xv] Id.
[xvi] Id.
[xvii] Id.
[xviii] Id.
[xix] Id.