Equine Limb Amputation and Prosthetic Limbs
Last summer a 10-year old Tennessee Walker mare with a large (approximately 10 inch diameter) mass over the right hind fetlock was presented to us. Radiographic evaluation demonstrated irregular bony surfaces and collapse of the pastern joint. Palpation of the limb confirmed that the tendons had been severely damaged by the growth of the mass, leading to contraction. Due to the extent of the mass and associated destruction of bone and soft tissue, surgical removal was not an option. The suggested treatment was limb amputation followed by placement of a prosthetic limb.
Limb amputation has been performed in horses previously, although it is not considered a common procedure. Due to their large size, horses (unlike companion animals) require the support of a prosthetic limb following amputation or excessive breakdown of the opposite limb will occur. Several conditions may lead to consideration of limb amputation, including fractures, septic arthritis or cellulitis, and destructive masses as in the case of this particular mare. Available equine limb prostheses are designed only for amputations below the knee or hock.
Due to the potential for complications, many factors must be evaluated before planning limb amputation. First of all, the horse must be in good overall health because the process may require several general anesthesia episodes. The surgery itself has potential for complications including post-operative infection, especially if the initial condition was a septic arthritis or cellulitis. In addition, the horse must have an ability to adapt to new situations, including being lifted in a sling and wearing a cast or prosthesis. Failure of the limb opposite to the amputated limb due to the weight-bearing increase is the most common cause of euthanasia following this procedure. The opposite limb must be closely evaluated for laminitis or founder, chronic sole abscesses or damage to the supporting tendons and ligaments. Another factor that affects the outcome is the owner’s commitment, since the horse will require continued bandages, prosthesis changes, and maintenance. The desired result following limb amputation is that the horse will live comfortably in a controlled paddock environment and will be able to be used for semen collection or as a brood mare.
To prepare for this mare’s prosthesis, the mare was anesthetized and a cast was made of the right hind limb prior to amputation. The cast was removed and sent to N.T.D. Equine Bracing to be used as a mold to design and build the prosthesis. Once the prosthesis was completed, the mare was taken to surgery for amputation of the limb below the distal hock joint. In the recovery box, a sling was used to hoist the mare, and the prosthesis was placed on the limb. The mare handled this procedure very calmly and was able to walk to her stall with the prosthesis in place. The mare gradually became more comfortable using the prosthesis, and was able to lie down and stand again shortly following surgery. The mare remained in the clinic for several weeks post-operatively for daily bandage changes and close monitoring of the surgical site. Routine farrier work has been performed every six weeks since the amputation with the mare being placed in the sling to provide support while the opposite hind limb is trimmed and shod. Six months have elapsed since the surgery and the mare is comfortable using the prosthetic limb in a pasture environment. Plans are currently being made to breed the mare this spring.
