Antler Harvesting: Techniques and Controversies
Murray Woodbury DVM, MSc.
Specialized Livestock Research and Development Program Department of Large Animal Clinical Sciences Western College of Veterinary Medicine University of Saskatchewn Saskatoon, Saskatchewan S7N 5B4
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As a surgical procedure, antler removal is as challenging as sawing through firewood. The stag is suitably restrained and fitted with a tourniquet, a likely plane of separation is sighted, and with a sharp saw the animal is separated from its antler. How has this rather simple process become one of the most controversial procedures in agricultural veterinary medicine?
Firstly there is the surgery itself, which is not much more involved than the description provided above and is similar in many ways to dehorning cattle. Most Canadian provincial Veterinary Acts allow the dehorning of cattle by the owner or caretaker of the cattle, but do not mention the removal of soft growing antler from cervids. This process, often referred to as "velveting" because the removal is done in the velvet stage of antler growth, is defined by default in most legislated Veterinary Acts as surgery. It is therefore technically illegal for anyone except a veterinarian to de-antler an animal.
The timing of antler removal is paramount to the market value of antler. The antler needs prompt removal when maximum growth before the onset of calcification has occurred. A delay of one or two days may result in downgrading of the antler quality. Since this is a matter of economic urgency but is not a medical emergency, veterinary help is not always available at the appropriate time. Moreover, in a large herd velveting is often carried out over a period of weeks with one or two animals being done daily as they become ready for harvesting. What veterinarian has time to be driving around the countryside, doing one or two animals on each property for a few weeks at a time? What producer can afford to pay the mileage charges for veterinary help on this basis?
So, on one hand velveting is a relatively simple procedure, somewhat similar to a familiar farming practice carried out by producers everywhere. And, it also appears to be inconvenient and impractical to summon professional help when antlers need harvesting. On the other hand, antler removal by anyone other than a veterinarian is illegal in most provinces. It is illegal because the veterinary profession has been placed in a position of responsibility for the humaneness and proficiency of medical practices carried out on animals. Legislators have enacted laws on the behalf of Canadian society to protect the welfare of animals and the safety of the food supply. This is affirmation that society sees members of the veterinary profession as highly skilled advocates of animal welfare.
Game farmers take a slightly different view of the issue. Faced with the expense and impracticality of seeking professional help, they see the current laws on antler removal as being protectionist and unreasonable. Many game farmers are highly skilled at antler removal, having done it for many years, and are justifiably sceptical of inexperienced veterinarians who insist that removal must only be performed by licensed members of the veterinary profession.
The argument about who should be holding the saw obscures larger and more important issues. While the actual amputation of antler is rather simple, the peripheral activities of animal handling, restraint, and analgesia are frequently not. There is great potential for harm to the animal and to the producer if these aspects of the process are poorly performed. There are animal welfare concerns such as inappropriate and harmful physical and chemical restraint, and inadequate local anaesthesia resulting in a painful amputation. There are safety concerns over accidental human exposure to anaesthetic drugs, and drug residues in animal products derived from treated animals.
The debate over the control of acquisition, distribution and use of veterinary drugs in the livestock industry rears its ugly head once more. There is nothing new here. There are many game farmers who will never be convinced that veterinary control of the distribution of prescription drugs used during antler harvesting such as xylazine, and most recently lidocaine, is anything other than an attempt at monopoly and a money grab.
Ignoring the element of whom is performing the velveting procedure,
let us look at the peripheral activities of animal handling, restraint,
Cervids do not respond to handling in the same manner as less recently domesticated animals. They are handled much more passively than cattle, sheep or horses. Rapid movement, noise and unfamiliar situations or people will cause exponential increases in stress levels. Stress and panic can easily be transmitted through a group of elk or deer, resulting in physical injury and psychological distress as the animals run blindly at fences or inflict displacement aggression on each other.
Cervids do not respond well to the use of electric prods or other implements often used for inducing cattle to move. The use of physical violence or painful stimuli is unacceptable and dangerous for both animals and handlers. Instead, use sensible strategies for moving cervids through handling facilities specifically designed and constructed for cervids. The facilities, including pasture and raceway layout, can make moving elk and deer very easy or a complete nightmare depending on the amount of attention paid to the specific requirements of cervids.
In addition to the general statements above, here are some specific strategies used to decrease the amount of stress and distress inflicted upon animals during the velvet harvesting procedure.
- In a large operation, pre-sort animals into smaller velveting groups according to their anticipated antler removal dates. This prevents the need to move and handle the entire herd when individuals become ready for harvest.
- Ensure that stags are acclimatized to the velveting chutes and squeeze by allowing them access to the facilities to explore in advance of any antler harvesting. Place some feed in various locations, or move them through the system without performing any other treatments.
- Do not isolate individuals for prolonged periods. Avoid processing only one animal. If this is necessary make sure that the animal is returned to a group as soon as possible.
- Allow animals to be velveted to settle before moving into the chute system. They will be quieter in the squeeze and if sedation or chemical restraint is needed will show much better response to the drugs.
- When possible, after velveting hold animals in easily accessible observation pens that do not allow visual contact with the velveting crew and subsequent velveting procedures. The stag will not feel like he has escaped until he can no longer see the perceived danger from which he is escaping.
- Avoid close handling of animals or velvet harvesting when the weather is hot and humid. Hyperthermia will frequently occur. This may result in stress related myopathies and metabolic collapse.
- Do not be in a hurry. Your patience will be rewarded with fewer injuries and problems.
If the first contentious point about velvet antler removal is who should perform the amputation, then the second and perhaps more inflammatory issue involves the methods of animal restraint used to allow amputation.
The two generally used methods of restraint are physical and chemical. Combinations of these methods are used, depending on the circumstances. Some form of physical restraint is almost always applied in the form of a squeeze chute, with or without sedation. In the absence of adequate facilities for physical restraint the method of choice becomes general anaesthesia using immobilizing doses of drugs such as xylazine, frequently in combination with other drugs like ketamine. This method of restraint is not practical on a large scale but is useful for operations with a few stags that can be done on the same day. It is my firm conviction that despite the Schedule F prescription status of drugs like ketamine and Rompun™ , their use to achieve general anaesthesia in game farmed animals should remain the responsibility of a licenced veterinarian. This view is of course opposed by many game farmers as being another example of protectionism and turf warfare. Whatever your own views on this subject, you are reminded that the responsibility for the correct use of these drugs and any consequences arising from their misuse remains with the dispensing practitioner. Since the use of most conventional sedatives in cervids is "off label", the legal responsibility for animal losses will not be shared by the drug manufacturer.
The ideal physical restraint device for antler removal is a hydraulic or pneumatic squeeze chute which allows the gentle but firm confinement of the stag with his head and antlers exposed for antler removal. Squeeze chute designs for elk are very sophisticated, with various padded and adjustable features allowing containment of the animal in a safe and comfortable manner. Deer chutes need not be as strong or sophisticated because of the smaller physical size of deer. However, all but the most unmanageable animals of any species can be squeezed and held still without using sedatives. Older experienced animals tend not to panic as much as young stags while being held. All animals benefit from the application of a blindfold. The blindfold reduces random visual stimulation and has a definite calming effect on animals.
Most squeezes allow some degree of head movement. If desired, complete immobilization of the head can be achieved using a halter and lateral tying. A regular horse halter is adapted by attaching ropes to the rings found on each side of the nose band. When the halter is fitted to the animal and the ropes are firmly tied down to cleats on the squeeze, the head is held motionless allowing easier cutting of the antler.
In the recent past, the need for sedatives, halters, and sometimes suitable squeeze chutes was obviated by using electro-immobilization to render the animal motionless. Most proponents of electro-immobilizing devices first provided physical restraint with a squeeze and then applied the electrical device to the stag to prevent any struggling during antler amputation. There is no question that electro-immobilization is effective for the purpose of restraint. Whether this method of restraint is humane or not is another matter.
Great Britain has banned the use of electro-immobilizers for any species.
The use of electro-immobilizers for antler removal is not permitted in
New Zealand or Australia. The Canadian Veterinary Medical Association (CVMA)
" finds the use of electro-immobilization unacceptable." The CVMA has taken
this approach to the problem because there has been no scientific evidence
that the use of electro-immobilizers does not cause distress to animals
on which it is used. The use of electro-immobilization for restraint during
antler removal has largely been discontinued by antler producers in favour
of "animal friendly" hydraulic restraint chutes.
Prior to antler removal some form of anaesthesia must be administered to the animal so that amputation is painless and humane. General anaesthesia, when used as a form of restraint, also provides adequate analgesia. Chemical immobilization with sedative drugs is not really the same as general anaesthesia and heavily sedated animals frequently need additional pain control in the form of local anaesthesia.
Presently the only universally accepted form of pain control for de-antlering stags that are not under general anaesthesia is the application of nerve blocks to the antler pedicle using lidocaine or a similar local anaesthetic solution. The Model Code of Practice for the Welfare of Animals: The Farming of Deer (Australian), The Code of Recommendations and Minimum Standards for the Welfare of Deer During the Removal of Antlers (New Zealand), and The Recommended Code of Practice for the Care and Handling of Farmed Deer (Cervidae) [ Canada] have guidelines for the removal of velvet antler that have been created and agreed upon by the respective industry representatives, animal welfare organizations and veterinary associations. These guidelines call for the application of local anaesthetic infiltration techniques to block pain sensation to the antler and pedicle.
A regional nerve block to the antler pedicle requires injections to the infratrochlear and zygomaticotemporal nerves which are the major sources of sensory input to the antler. Often there is minor input or innervation of secondary importance from the dorsal branch of the auriculopalpebral nerve. Complete blockage of nervous impulses requires the injection of local anaesthetic to this nerve as well.
A ring block placed around the base of the pedicle obviates the need for precise placement of local anaesthetic solution to achieve antler anaesthesia. A series of small overlapping line blocks using a dose rate of 1.2 ml of lidocaine per centimetre of pedicle circumference (total volume of approximately 20 ml per antler) are placed under the skin on the head around the base of pedicle. In places where the skin is closely adherent to the skull infiltration can be somewhat difficult. Persistence and practice combined with physical force will overcome these difficulties. After 4 or 5 minutes the innervation to the antler will be sufficiently blocked to allow amputation. An article published in the Canadian Veterinary Journal (August 1996; 37:486-489.) describes the innervation of the antler and these local anaesthetic techniques in greater detail.
Many game farmers who harvest antlers complain that the use of local anaesthetic requires that the animal spends too much time in physical restraint. They maintain that the process of squeezing the animal for a 3 - 5 minute period and applying nerve blocks is at least as stressful to a cervid as having the antler removed rapidly but without any anaesthesia or analgesia. I cannot condone performing painful procedures without adequate pain control but they do have a legitimate point concerning the amount and duration of physical restraint needed. A local anaesthetic technique with a more rapid onset would be of great value.
Many believe that electro-anaesthesia (EA) may be the anaesthetic technique of choice for antler removal. It is important to distinguish between electro-anaesthesia and electro-immobilization. Electro-immobilization and the devices used to produce it are designed for restraint and immobilization. There are claims about the analgesic effects of this procedure but these are unsubstantiated. EA, on the other hand, has been used since the early 1970's in such human applications as dentistry and post operative patient care where its analgesic effects are well documented.
One form of EA is perhaps better known as transcutaneous electronic nerve stimulation (TENS). TENS can be achieved by applying ultra high frequency electrical impulses to nerves by means of electrodes placed strategically near the site to be anaesthetized. The electrical impulses act to attenuate neural depolarization and transmission. Depending on the efficiency of the electro-anaesthetic unit in supplying the correct degree of electrical stimulation at the appropriate location, partial or complete local anaesthesia is achieved in human patients. The EA apparatus most commonly used for antler removal procedures is one originally designed to provide dental analgesia in humans.
The nature of the electrical stimulus used for EA is not the same as that for electro-immobilization, perhaps supporting the belief that electro-immobilization units cannot be used to provide electro-anaesthesia. A typical EA apparatus uses a 9 volt battery and operates (pulses) at up to 60 milliamps of current delivered for up to 250 microseconds, at a rate of up to 140 pulses per second. The characteristics of the pulsatile current are adjustable using controls on the generating unit. This is apparently sufficient electrical interference to cause reversible chaos in sensory neurons.
For local anaesthesia during antler removal, game farmers have been using EA units as follows. One electrode is placed on each ear, or on one ear and the contralateral lip. Alternatively, one electrode is placed onto the scalp in front of the pedicle and the other behind the pedicle. The apparatus is switched on and after a waiting period of approximately 3 minutes a saw is used to amputate the antler. Proponents of EA maintain that aversive movements or behavioural indications of pain during antler removal are uncommon.
This seems too easy and good to be true. Perhaps it isn't true. Although EA is useful and proven to be effective in human medicine, the circumstances and conditions of use so easily achieved in situations with human patients may not be feasible or possible when EA is used on elk and deer. Neuroanatomy and physiology is not necessarily the same in all animals. Methods used in human dentistry may not be directly applied to antler removal in cervids. There is no question that EA might work in certain situations or in certain individuals but is this a reliable method of analgesia that has broad applications for pain relief during antler harvesting?
Here are some observations about the general use of EA units:
- Failure of local anaesthesia provided by the injection of anaesthetic solutions is seldom complete but some degree of pain relief is almost always achieved. Failure of the EA unit because of electrode failure or unit malfunction would allow the immediate and full experience of pain.
- Literature describing or promoting electro-anaesthesia methods advocates its use as an adjunct to other forms of anaesthesia but does not often advocate the total replacement of conventional anaesthesia except for minor procedures. EA applied to the central nervous system has been shown to decrease the level of general anaesthetic needed during surgery, and shortens anaesthetic recovery but does not replace general anaesthesia. Dental units are promoted for use during, not instead of, local anaesthetic injections.
- Even the manufacturers of electro-anaesthesia units indicate that the system is not appropriate for all procedures nor for all patients. Dental units are useful during oral hygiene and periodontal procedures, restorative procedures on small to moderate lesions, and temporomandibular dysfunction. None of these procedures even approaches the level of pain involved with the amputation of a well innervated body part.
- How do we deal with those patients in which electro-anaesthesia is not effective? Indeed, how do we know in our case which patients those are? By adjusting the level of electrical current it is sometimes possible to increase the analgesic properties of EA until the human patient is comfortable. How is this reliably accomplished with animals?
- Enthusiasm for an idea often distorts facts and inflates the truth a little. For example, detractors of local anaesthetic infiltration methods often cite the disadvantage of delayed onset of satisfactory effects and point out the advantage of an almost immediate analgesic effect observed when using EA. The instruction manual for the 3M™ Dental Electronic Anaesthesia System indicates that "it will take 2 - 5 minutes to achieve a therapeutic level". This is the same time requirement for effective injectable anaesthesia application.
Another non chemical technique for antler anesthesia is compression anesthesia. Compression anesthesia involves the application of pressure to nerves to remove sensation prior to the application of a painful stimulus. This method was used as early as the 17th century to provide pain relief to soldiers with shattered limbs from battle. More recently it has been trialed as an anesthetic method for antler removal in red deer spikers and fallow deer in New Zealand and Australia with promising results. A tightly stretched rubber ring is placed around the pedicle and left in place for a period of time. The ring compresses the nerves on the pedicle leading to the antler, rendering the antler insensitive to pain. In New Zealand studies the rings were placed for a minimum of one hour and a maximum of two hours but an optimum time or a minimum effective time was not established. The obvious drawback to compression anesthesia is the waiting period prior to antler amputation and the need for removal of the ring. Failure to relieve the compression would result in ischemic necrosis of the pedicle distal to the compression ring.
The search for ideal methods of antler removal continues. The ideal method would provide easily applied, rapid, fully effective, long lasting, reliable analgesia yielding a residue free antler product at a reasonable cost with maximum safety and minimal stress to the animal. Above all, the humaneness of the method should not be compromised by economic considerations.