Page 114 - November 2021

VETERINARY VIEWS
boot, a combination of fleece and elastic wrap, and
a polo wrap. Each horse wore a boot or bandage on one forelimb while the other forelimb was bare to serve as a control. A
temperature-reading device behind the lateral splint
bones recorded every minute for 20 minutes of exercise
and 180 minutes of recovery at a standing position in moderate
ambient conditions. The results are telling:
• At minute 9 of exercise, the bare limb temperature was lowest (~ 81 degrees Fahrenheit).
• At 15 minutes of exercise, booted or wrapped limb temperature increased from 90 degrees Fahrenheit at the start of exercise to 97 degrees Fahrenheit. This plateaued during recovery.
• Compared to the bare limb, all booted or wrapped limbs experienced higher temperatures.
• The polo wrap was hotter and had the highest humidity (94%) compared to the other boots.
• All treatments failed to return to baseline temperature and humidity after 180 minutes. The study concluded: “Convection cooling is impaired by boots and wraps during exercise
such that even in a moderate intensity exercise bout in moderate ambient conditions, a booted or wrapped limb may reach damaging temperatures.” Keeping in mind that the
bare limb also did not return to baseline temperature within 180 minutes of recovery,
it is necessary for riders to implement other passive cooling strategies of the limbs using ice packs or cold/ice water.
POST-EXERCISE “SUPPORT” BANDAGES
Bandages of various kinds, like polo wraps and leg quilts, are used to ‘support’ soft tissues of a limb following exercise or for soft tissue or orthopedic injury. Support, in this case, means that bandages keep soft tissues from swelling with tissue edema related to inflammation.
The direction in which to wrap a bandage has taken on an unusual degree of significance
to horse owners over the years. Ideally, the bandage is “pulled” around the front of
the canon bone and “layered” lightly over the flexor tendons, which is the location of the major blood vessels to the distal limb.
A bandage applied too tightly can result in limb edema, pressure points, or circulatory disturbance with limb and life-threatening avascular necrosis. The direction of wrap has little impact provided the bandage is applied evenly and in appropriate tension.
THE BOTTOM LINE
The assortment of commercially available protective leg boots is vast in choices, but riders should be aware of the pros and cons of their use and should adjust expectations realistically. Ultimately, there is no substitute for leg protection like the benefits gained from proper conditioning and skill training of a horse for their intended athletic pursuit.
Heat is generated by the stretch-recoil cycle in the tendons. Bandage wraps will diminish the normal convection cooling of the legs compared to when they are just exposed to the air.
TENDON DEGENERATION DUE TO HEAT BENEATH BANDAGES
There’s also a considerable concern about overheating of bandaged or booted tendons. Tendon-damaging temperatures around 113 degrees F (or 45 degrees C, a few degrees higher than normal) have been recorded in the core of the superficial digital flexor tendon, even after strenuous exercise of short duration. Heat is generated by the stretch-recoil cycle
in the tendons, yet bandage wraps diminish normal convection cooling of the legs when exposed to the air. Heat that develops in the central core of a tendon must dissipate as quickly as possible following work to avoid tendon degeneration. For a horse that has worked hard, cold hosing or icing the legs after removing wraps is instrumental in removing heat from the interior of the limb.
A study tested six boots or wraps in six sound, mature horses for their detrimental effects on heat accumulation in equine tendons. [Brock L, Spooner H. A comparison among equine boots and leg wraps on leg surface temperature during and after exercise. Journal of Equine Veterinary Science 2021]
A variety of boots were used: a neoprene boot, a perforated neoprene boot, an alternative neoprene boot, a cross-country
Bandages of various kinds are used to support soft tissues of a limb following exercise, or for soft tissue or orthopedic injury.
“The assortment of commercially available protective leg boots is vast in choices, but riders should be aware of the pros and cons of their use and should adjust expectations realistically.”
112 SPEEDHORSE November 2021