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How to Assemble, Apply, and Use a Head-and-Tail Rope System for the Recovery of the Equine Anesthetic Patient
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Recovery from anesthesia can be a difficult and potentially dangerous time for the equine patient. One method of providing a measure of safety and reducing the risk of injury during the post-anesthetic period is through the use of a head and tail rope system. The system aids in stabilizing the patient until it is able to stand unassisted.
1. Introduction
The use of head and tail ropes during equine anesthetic recovery is important to help ensure the patient's welfare. A head-and-tail rope system enhances the likelihood of good recoveries by assisting the equine patient in standing and preventing hard falls and stumbling. In many institutions and practices, the patient is allowed to stand on its own, without assistance, whenever it is able. Although this may be suitable in many cases, perhaps even the majority, there is increased risk to the patient during recovery. After orthopedic procedures, this may be even more significant, given the inherent risk that accompanies these patients. The disadvantages to the system come in the form of increased costs for the equipment and the personnel required to operate it. The advantages, however, may offset the disadvantages when considering the patient's well being. Post-anesthetic complications or injuries are factors that must always be taken into account at recovery. As of this writing, there were no data on recovery rates at Texas A&M University before the implementation of the head and tail rope system. The authors' clinical impression is that using this system to aid the equine patient during recovery reduces the likelihood of complications and injuries to both patients and handlers, and it affects the recovery rates only minimally.
The majority of equine patients recovering from gas anesthesia achieve recovery to standing within 1 h. Recovery rates for orthopedic patients may be slightly longer, particularly those having undergone extensive procedures such as long-bone fracture repairs. The head-and-tail rope system most benefits those patients who are most at risk for post-anesthetic complications.
2. Description of the System
The head rope consists of a standard-size equine halter, preferably of nylon construction for wear and durability. The halter should be large enough to fit over an equine recovery hood whose use is recommended after anesthesia. The rope should be of rugged construction, preferably double-braided cotton or a cotton/nylon blend. The rope works best if it is ~0.75 in diameter and braided through the halter in a permanent manner, as in a lead rope. This is preferred over the use of a buckle or snap because of safety concerns for the horse as well as the handler should a buckle break or become loose during a difficult recovery. The rope should be at least 35 ft in length to provide the handler with ample freedom of movement during recovery but not long enough to entangle or be cumbersome for the user.
The tail rope consists of a two-pulley system, which provides the user with a large mechanical advantage in preventing the equine patient from falling or stumbling forward. The pulleys used in this system consist of a double-wheel (sheave) or "fiddle block" pulley obtained from a sailing outfitter (Fig. 1) [a]. Each pulley has an attachment mechanism, or "becket", on one or both ends to which are affixed ropes or chains used in applying the system during recovery. The lower pulley (Fig. 1) is closest to the horse and has two sheaves that both turn freely on bearings. The upper pulley (Fig. 1) is closest to the wall and is also double sheaved, but the larger, upper wheel (Fig. 2) has a ratchet lock that prevents the wheel from turning backwards against the pull of the rope while under tension. This provides the handler further assistance in maintaining proper control of the patient.
Figure 1. Fully assembled, the tail rope system appears with the chain and carabiner, and the "upper" ratchet pulley (A). The "lower" pulley (B) is shown with the shorter tail rope attached.
Figure 2. Upper pulley demonstrating upper and lower sheaves (wheels), and ratchet lock on the front.
3. Assembly of the System
When assembling the tail-rope device, be sure to follow the manufacturer's recommendation in choosing the appropriate diameter rope for the pulley system used. One end of the main rope is attached to the bottom eye of the upper pulley (Fig. 3, Letter A0076f3). This end is a static point and will not move, and it should be fastened in a solid, permanent way. A good method of attaching this end is through the use of a rope clamp holding the tag end of a small, tight knot. This end may also be braided permanently, assuming the braiding is done expertly, because this end is a most critical link in attaining a reliable system. The rope is then passed through the entire pulley system (Fig. 3) starting at the upper pulley becket to the top sheave on the lower pulley to the bottom sheave on the upper pulley to the bottom sheave on the lower pulley to the top sheave on the upper pulley and the remaining rope to the handler. The rope that will be attached to the horse should be ~0.625 inch in diameter and 6 - 8 ft in length, and it should be fastened in a permanent way to the bottom ring of the lower pulley. When configured, the tail-rope system will then appear as follows: (1) the upper ratchet pulley is attached to the wall with a chain and carabiner; (2) the main rope is threaded through both pulleys so that the lower (non-ratchet) pulley is closest to the horse; and (3) the tail rope attaches from the becket of the lower pulley to the horse.
Figure 3. Tail rope disassembled to demonstrate path of the main body of the tail rope. (A) Becket on the upper pulley, (B) upper sheave, lower pulley, (C) lower sheave, upper pulley, (D) lower sheave, lower pulley, (E) upper sheave, upper pulley, and (F) remaining rope to handler.
4. Application of the System
The head-rope system is applied to the patient when it is still asleep on arrival at the recovery stall. The head-rope halter is applied to the horse over the recovery hood (Fig. 4) [b]. It is important that the buckle be tightened behind the hood, because the halter may not be tight enough if placed entirely over the hood. The loose end of the head rope is passed through a bar on the wall, and the rope should move freely and easily around the bar.
Figure 4. Horse in lateral recumbency with recovery hood in place, showing head rope halter over recovery hood, and buckle being fastened behind recovery hood. Endotracheal tube is shown taped in place.
The tail rope is first attached to a post in the wall using a small length of chain and a good quality carabiner [c] that may be purchased at a sports or specialty climbing store. Be sure that the carabiner is locked. Failure to properly lock the mechanism may cause the entire carabiner to open or break while under stress. The tail rope is attached to the horse in the following manner: (1) find the last coccygeal bone of the tail; (2) pass the tail rope across the tail just below this point and as close to the bottom pulley as possible; (3) fold the tail back on itself tightly and wrap the rope around the folded portion of the patient's tail; (4) make two or three loops around the tail and lock the knot into place by passing a portion of the rope under the first loop closest to the pulley to form a knot that tightens when under tension; and (5) tighten and test the knot by pulling hard on the tail rope at the lower pulley (there should be very little slippage of the tail knot).
5. Using the Head-and-Tail Ropes
The patient should be in a dimly lit recovery stall large enough to accommodate some free movement of the horse and the handlers during recovery. Whenever possible, the horse should be placed in a lateral recumbency that would place an affected limb facing up. As the horse begins to recover, it may be necessary to provide some IV sedation (xylazine, 0.1 - 0.15 mg/lb) to allow the anesthetic gas to be completely metabolized and "blown off" before allowing the horse to stand. Monitor the patient's eyes for signs of nystagmus, which would indicate less than optimal timing for allowing the horse to stand. When the horse appears more aware, as shown by more conscious movements of the eye (following hand movements and looking around) and generally looking more awake, swallowing and control of the tongue, and movements of the legs, the patient may then be allowed to stand.
Generally speaking, the head-and-tail rope system is used to provide stability to the patient when it begins to rise to a standing position. It should never be used to force a horse into standing, because this is neither possible nor desirable; it could result in injury to the horse and/or handlers.
As the horse begins to stand, there is a general tendency for it to move forward against the pull of the tail rope. The person operating the tail rope should balance the tension applied to the rope between pulling too hard (possibly spooking the horse into fighting the tail rope) and not pulling hard enough to provide stability of the rear part of the horse. As a general rule, the ropes should be pulled only when necessary and only as hard as necessary to prevent hard falling should the patient become unsteady.
The head rope, which provides little mechanical advantage to the user, should be manned by someone strong enough to control it. This does not imply that the head rope must necessarily be pulled hard during standing. As with the tail rope, the head rope is used only to provide stability to the horse. If the horse begins to wobble, the head rope may be pulled during the time when the horse feels itself falling and loosened when the horse rights itself. Often, the horse may want to turn around, and with that effort, it may become unsteady. It is necessary, therefore, to maintain a small amount of tension on the head rope to keep the head pointing forward. This slight control of the head may put many horses at ease, because most are accustomed to the feel of a halter. If it becomes clear that the horse is unable to stand, as sometimes happens (e.g., if the patient develops nystagmus while standing) then both head and tail ropes may be used to prevent the horse from falling hard and to allow it to lie down in a safe and controlled manner away from the handlers.
When the horse is standing and stable, as evidenced by its ability to easily maintain its balance, lack of nystagmus, and general awareness, the recovery hood may be removed from under the halter, leaving the halter in place for a few more minutes as a safety precaution. The tail rope is then removed, followed by the head rope. The horse may now have a regular halter and lead placed and be led from the recovery room.
6. Conclusion
The use of a head-and-tail rope system provides an alternate and safe method for recovering equines from anesthesia. Although the traditional method of recovery may be suitable in many cases, the head-and-tail rope system can contribute to safer recoveries in almost all patients, and it can play a positive role in the patient's overall welfare.
The authors thank Eric E. Swinebroad, DVM, as well as the Anesthesia Technicians at the College of Veterinary Medicine, Texas A&M University for their assistance and support.
Footnotes
- Harken, Inc., Pewaukee, WI 53072.
- Shanks Veterinary Equipment, Inc., Milledgeville, IL 61051.
- Petzl America, Clearfield, UT 84016.
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