Cryotherapy means cold therapy. In this case, freezing cold therapy. We’re not talking about freeze branding here, which has virtually replaced archaic hot branding, although it is the same principle. Cryotherapy is a medical treatment. Even your family physician may use freezing to remove warts or small skin lesions in his office.
Applications for horses are similar but also include control of chronic pain from a variety of problems. The only drawback is that the freezing destroys pigment cells in the adjoining normal skin, so skin and hair grow back white.
Cryotherapy can treat anything from juvenile warts to large malignant skin tumors. With small lesions, complete removal/cure is often possible with a single treatment. Even large sarcoids can usually be successfully treated with minimal scarring.
Cryosurgery can be used either before, after or in place of traditional knife resection. It may also be used to reduce the size of a tumor prior to radiation therapy. Cryosurgery is associated with excellent cosmetic results and minimal scar formation. If the lesion is not resected with a knife immediately before freezing, little to no bleeding occurs.
Aftercare consists of little more than gentle surface cleansing and spraying on a topical antibiotic. Complications, such as infection, are rare. Once all abnormal tissue is destroyed, the area will heal like any open wound but usually more quickly, without granulation tissue and with little-to-no scarring.
Splints And Bucked Shins
Cryosurgery works well for splints or bucked shins. Freezing the skin overlying the splint or cannon bone is done at one or more areas, as needed. The freezing has two effects: 1) It relieves pain; 2) It destroys all the frozen local soft tissues from blood cells to bone-forming cells, and the reaction is therefore quieted.
When the area thaws, the fluids are quickly taken up by the blood stream and dead tissues are removed by scavenger white blood cells. Fibroblasts then enter the area and replace the debris with new, smooth connective tissue. The splint or shin is smoothed out and quiet (with shins you must rule out impending saucer fractures before treating). Even high splints near or in the knee can be treated with no damage to the joint or joint capsule.
There is a high risk of a fractured splints irritating or damaging the suspensory ligament, especially once calcium deposits begin to form. Many vets believe the treatment of choice is removal of the fractured segment, especially if done soon after the fracture. Others believe that surgery eventually results in as much irritation and calcium formation as if the fractured splint had been left in place.
Freezing the tissues immediately overlying and down to the level of the fractured splint has been used successfully. Its proponents feel it is superior to surgery as it does not add to the irritation and inflammation already present.
In fact, in one series of 44 racehorses treated for fractured splint bones, 81.8% were back racing within 120 days of treatment, 60% racing in similar or higher classes. The authors of this study reported that even if a prominent callus/calcium collection was present before treatment, this would be resorbed and the area remodeled over time. The entire process could take up to six months, but the horse is comfortable during that time. As with horses treated surgically, involvement of the suspensory ligament in the callus/scarring lowers the prognosis.
Arthritis is a complicated condition, with abnormalities potentially arising from many different locations and tissues, including cartilage erosions, bone inflammation and proliferation (bone spurs) and an inflamed synovial lining. Extensive cartilage lesions, as you might have with OCD or advanced arthritis in the stifle when internal ligament damage has occurred, are not treatable by cryotherapy. However, when the changes and the pain are originating from irritation and bone spurs that are close to the skin surface, cryotherapy has been successful.
Dr. Les McKibben, of Wheatley Hall Farm in Ontario, an early pioneer in equine cryotherapy, reports excellent results with cryotherapy of “jack”/bone spavin, a degenerative hock arthritis where lesions are located primarily along the inner and front surface of the hock, in front of the chestnut. This is a common site for wear-and-tear arthritis in any horse and is particularly a problem for sickle-hocked horses and performance horses whose jobs entail a lot of hind-end stress.
The problem occurs in and around the attachment of the cunean tendon and is believed to be related to repeated pull on and irritation of the bones by this tendon. It is treated by freezing several points along the path of the cunean tendon, the same area where surgeons will remove a length of the tendon when treating the condition surgically (cunean tenotomy).
A report published in 1984 by Dr. McKibben stated that 95% of the horses treated in this manner returned to full competition at a level equal to or better than before the therapy, and 90% of the horses were only treated once.
This same clinic has used freezing to treat arthritis characterized by bone spurring in the knee. Results were available for only a small number of horses, but the procedure was 100% successful in them. As with any treatment, candidates must be chosen carefully. The best candidates would be those with changes related to overextension (e.g. Thoroughbred racehorses), rather than underlying disease such as OCD.
Another common joint-related problem that often responds well to cryotherapy is osselets, tearing of the joint capsule of the fetlock. Early, acute cases should still be treated with rest and aggressive cooling. However, horses prone to recurrent problems in this area and/or those who have small chip fractures that constitute a chronic focus of irritation and pain are good candidates.
Ankle And Foot Problems
Cryotherapy has been tried as a means of alleviating the pain associated with several longstanding conditions of the ankle and foot, but it is not a direct treatment of the condition. Like traditional surgical “nerving,” the goal of cryotherapy is to eliminate pain.
The procedure has been called “freeze nerving” by some but, unlike surgical nerving, the horse does not lose all sensation, just the chronic pain component (see sidebar, page 19). Two spots on either side of the leg are used, along the course of the volar (plantar) nerves — which become the digital nerves in the heel area — and over a spot at the end of the splint bone (to get a nerve branch that helps supply the front surface of the pastern and foot).
Results reported in the series of cases done at Wheatley Hall are variable, but success rates as good as, if not better than, with surgical removal of the nerves and without the risk of neuroma formation and with preservation of sensations of sharp pain, touch, pressure and position of the foot. However, cryotherapy should never be considered a substitute for careful attention to correct trimming and shoeing or other primary treatments. Its sole purpose is the control of chronic pain.
Variable success has been found in other ankle/foot conditions, such as ringbone or pedal osteitis. This is because: 1) Cryotherapy can’t treat the areas directly; 2) The nature of the pain is complex; 3) Accurately identifying and treating all the sensory nerves supplying the front of the foot is virtually impossible.
Tendons And Ligaments
Veterinarians differ in their opinions regarding cryotherapy and tendon or ligament problems. Some flatly state it is useless, while others use it frequently and as their first line of treatment. The discrepancy is largely explained by what effect you are after.
Cryotherapy will not produce dramatic pain relief with these soft tissue injuries, especially when there is an ultrasound-documented injury to the interior. Pain sensation from ten don/ligament injuries is complicated, can arise from multiple locations and cryotherapy can’t reach them. It is only effective long-term for C nerve/pain fibers, which are only a part of the pain picture and even when contributing may be located too deeply to be affected by surface freezing.
A notable exception is curbs, where the damage and pain occurs primarily at the attachment of the ligament on the back of the hock, close to the skin surface. Cryotherapy will also provide better pain relief in cases that primarily involve inflammation and damage to a tendon sheath, rather than internal tearing of the tendon.
Cryotherapy also has no effect on the speed or quality of healing of deep, internal tears in tendons and ligaments. However, there can be a more rapid resolution of swelling and heat in the area after cryotherapy. It has also sometimes been helpful in controlling pain and swelling in chronic tendon/ligament problems that are difficult to “set up.”
Cryotherapy has little competition for removing surface tumors/growths — it’s bloodless, quick, relatively painless and results in rapid healing.
It may also be the treatment of choice for bucked shins and splints. Freezing can also be effective in arthritis where the primary problem relates to bony changes at the edges of adjoining bones.
As an alternative to surgical neurectomy, it has distinct advantages in terms of preserving sensation while alleviating pain. It also works well for curbs and can assist in control of superficial injury or inflammation.
Also With This Article
Click here to view “How It’s Done.”
Click here to view “Our Experiences With Freeze Nerving.”
Click here to view “Pain Fibers.”