Volume 49 | Issue 1 Article 6

1987 Chemical Immobilization of Wild Ruminants D. E. Williams Iowa State University

D. H. Riedesel Iowa State University

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Recommended Citation Williams, D. E. and Riedesel, D. H. (1987) "Chemical Immobilization of Wild Ruminants," Iowa State University Veterinarian: Vol. 49 : Iss. 1 , Article 6. Available at: https://lib.dr.iastate.edu/iowastate_veterinarian/vol49/iss1/6

This Article is brought to you for free and open access by the Journals at Iowa State University Digital Repository. It has been accepted for inclusion in Iowa State University Veterinarian by an authorized editor of Iowa State University Digital Repository. For more information, please contact [email protected]. Chemical Immobilization of Wild Ruminants

D.E. Williams BS, DVM* D.H. Riedesel DVM* *

Historically, pharmacological immobilization can tact with mucous membranes can be lethal. be traced back to cenain tribes from South Amer­ Etorphine was first introduced in 1963 as a via­ ica who used curare-coated arrows in their quest for ble alternative to diethylthiambutene for the im­ food. Though this method was effective and curare mobilization oflarge ungulates. It quickly became derivatives were used for many years, an effon be­ one ofthe main immobilizing agents used in South gan in 1958 by rangers in South Africa to develop Africa, and since then many other countries have new and hopefully more efficacious methods to im­ done research on the safety and efficacy of etor­ mobilize animals for research.! Since that time, phine. At moderate doses, etorphine induces se­ great strides have been made in developing new dation but the animal usually remains standing, drugs and techniques for delivery of these drugs. and higher doses will cause the animal to become It is the purpose of this paper to consolidate and sternally recumbant. However, to obtain surgical review the latest developments in animal immobili­ anesthesia, a neuroleptic such as xylazine must be zation. used in combination with etorphine. 7 This combi­ nation will also decrease the respiratory and renal Compounds depression attributed to etorphine alone. Many different classes of compounds including When etorphine was first introduced the dose was anesthetics, analgesics, sedatives and tranquilizers calculated by trial and error, but now recommend­ have been used to immobilize animals. Today, ed doses are available for many species (Appendix however, only a few of these compounds can be I). Most are in the range of 1.0-1.75 mg/45 kg used on a regular basis due to federal regulations. (100#), however, the exact dosage of etorphine One of these regulations, the FDA's Controlled varies depending on the species and the health and Substances Act of 1970, restricts the use and dis­ excitement ofthe anima1. 4 It is commercially avail­ tribution of some of the more potent drugs such able in the United Kingdom as a 2.45 °/0 solution 2 as opioids. Fortunately, there are other drugs which combined with acetylpromazine, and it is approved are just as effective and more accessible. for use as a 1°/0 solution by zoos in the United States. Opioids Carfentanil is a highly potent synthetic opioid, This class ofdrugs has three advantages: (1) they reponed to be 50-100°A> more potent than etor· are easy to administer (due to the high potency of phine.6 It is supplied as a 1 Ok solution which must the members used, less than 1 ml can immobilize be diluted with sterile saline (1 :4) for use in most most'animals), (2) their high therapeutic index, and species. Doses of .9-1.5 mg/45 kg have been used (3) the availability ofantagonists to reverse their ef­ to immobilize mule deer6 and moose.' In these fects. The most two popular opioids are the highly studies, it was used either alone or in combination potent thebain derivatives: etorphine,3,4 and with acetylpromazine or xylazine, the latter two carfentanil. ',6 Because of their extreme potency, drugs being used to increase muscle relaxation. opioids must be handled with care by the people More research must be done to evaluate carfentanil administering them; accidental self-injection or con- before it is released for more extensive use. Only one company is licensed to distribute the drug in *Dr. Williams is a 1986 graduate of the College of Veterinary the United States. Medicine at Iowa State University. **Dr. Riedesel is a professor in the Department of Veterinary A distinct advantage ofopioids as immobiliz­ Clinical Sciences. ing agents is that their action can be reversed by

26 Iowa State University Veterinarian the use ofopioid antagonists. These antagonists in­ ers. Studies done on dogsl5 and cattle 16 have fo~nd clude diprenorphine, cyprenorpmne, naloxone, and it to be a suitable substitute for yohimbine, and nalorphine. When they are used in animals not un­ in some cases was the preferred drug due t{> its more der the influence of one of the other opioids, all complete and longer lasting reversal. 17 More research with the exception ofnaloxone will bind to opiate must be done to substarit.ia-te these claims. receptors of the body and cause a morphine-like response. However, when used after the aforemen­ Tranqulliz~rs tioned opioids, they reverse the opioid effects. This The most commonly y~~4 tranquilizers are the is thought to be a type of competitive inhibition, phenothiazine derivatlv,~s. 'These drugs cause seda­ displacing the more potent opioids. tion and muscle r~laxation, but are not potent Dosages of each of the antagonists should be enough to be used alone. In a study by Pusateri,18 checked before any opioids are used. There is quite promazine was used ~ an oral immobilizing agent a wide dosage range depending on the immobiliz­ in pronghorn antelope~ Doses of 2-17 mg/kg had ing agent used. For example, a 10 mg dose ofetor­ no effect on these animals no matter what the age phine requires 20 mg of diprenorphine to reverse or condition. It has also been the author's ex­ its effects;3 however, the same dose of carfentanil perience that twice the recommended equine dose requires 100 mg of diprenorphine for adequate of promazine HCl (5 mg/kg) added to grain would reversal. 6 not sufficiently tranquiliz~-a tame, 6 year old, fe­ How~ver, Sedative Analgesics male white-tailed deer for capture. acetyl­ promazine is very useful whgn used in conjunction Xylazine, an alpha-2 adrenoreceptor agonist, is with opioids or phencyclidin~ derivatives to decrease the most commonly used drug in the sedative anal­ their side effects. When used 1n combination with gesic category. It has many of the same effects as other agents, acetylpromazil1~ dosages range from the opioids without the CNS stimulation. Xylazine .05 ... 5 mg/kg. produces muscle relaxation and sedation (in most Another group of tranquilizers frequently used animals) and some analgesia.8 However, animals are the benzodiazepine derivatives. Diazepam (Val­ under the influence of xylazine can still react to ium) has been used as an oral immobilizing agent. painful stimuli, so proper restraint must always be It, unlike the promazines, has enough sedative ac­ employed when using this drug to prevent injury tion to make tame pronghorn antelope manag­ to the animal and personnel. able. 18 It was most effective in the adult animal at Sedation can be obtained with doses of .5-2.0 a dose of 7.. 23 mg/kg. Fawns were not affected sig­ mg/kg, whereas complete immobilization requires nificantly by these doses. 3-8 mg/kg. Dosages can vary depending on age, degree of excitement, and species, e.g. Jacobsen9 Neuromuscular Blocking Agents has found that black-tailed deer that were alarmed required twice the dose of deer that were calm. These agent~ have been used for many years to Fawns weighing 10-20 kg required dosages higher immobilize wild ruminants. The most popular drug than either younger or older animals. in this class is succinylcholine. However, in recent For many years, the main disadvantage ofusing years, its use has diminished mainly because ofits xylazine was the lack of a good reversal agent and low therapeutic index and the lack of a safe and therefore long periods of unnecessary immobiliza­ effective reversal agent. An overdose ofsuccinylcho­ tion. Recently, research has been done on an line will cause diaphragmatic paralysis, which is alpha-2 adrenoreceptor blocker called yohimbine. lethal if resuscitation equipment is not available. It has been used extensively and with good success Therefore, its use is not recommended. Dosages of in white-tailed deer,7.10-13 mule deer,13,14 moose,5 .02-.05 mg/kg have been used in the past with only and bighorned sheep. 13,14 The average arousal time moderate death losse~~! after intravenous injection of yohimbine is 4 min. If 4-aminopyridine is used along with yohimbine, Phencyclidine Derivatives arousal occurs in an average of 2.5 min. 13 This is The phencyclidine derivatives, which include due to the complementary effects of these two phencyclidine and ketamine, are classified as dis­ drugs, an acetylcholine releaser and an alpha-2 sociative anesthetics. This means they dissociate the blocker respectively. central nervous system causing immobilization.8 Tolazoline, a vasoactive amine used in human These drugs also cause catatonia and increased sali­ cardiotherapy, has also been successfully used as a vation while having minimal effect on reflexes such xylazine reversal agent by some zoos and research- as swallowing and blinking.

Vol. 49, No. 1 27 Phencyclidine (PCP) was fust used by Harthoorn used. The collar is pushed back on impact and the in the late 50'S.1 It was found to be an effective immobilizing agent is delivered. anesthetic agent for small nuninants, but was taken Another type of syringe uses an acid-carbonate offthe market in the 70's because ofhuman abuse. system. 19 This syringe uses a pelleted or powdered Ketamine, on the other hand, is still getting limit­ carbonate separated from the liquid acid by a di­ ed use in small ruminants such as black-tailed deer. aphragm or plug. On impact, the diagram is broken It is usually used in combination with xylazine to and the chemicals mix. To accomplish this, vari­ decrease the catatonia. In one study, this combi­ ous lead weights are used (Figure 1). These syringes nation was used on white-tailed deer at a dosage have the disadvantage ofdelayed drug release, since of 1-2 mg/kg xylazine and 6-8 mg/kg ketamine. it takes time for the chemical reaction to occur. They This is equivalent to a 1: 1 combination of small also have a tendency to bounce out before injec­ animal Rompun (20 mg/ml) and Ketaset (100 tion is complete. These problems can be remedied mg/ml) used at a rate of 1 m115-10 kg. by the use of barbed needles. Another combination is ketamine and acetyl­ The last major type of syringe (projectile) is the promazine. This was used by the a,.uthor at 3 times percussion cap syringe, which is probably the most the recommended dose in an attempt to anesthe­ widely used. Caps or powder charges are used to tize a 2 month old male white-tailed deer. At this inject the agent. They have some type of internal dose, the fawn became only slightly ataxic. No more triggering mechanism to set offthe charges, which was given because ofthe threat ofhyperthermia and vary in size depending on the syringe volume. hypoxia from high environmental temperature and The main disadvantage ofthis type ofsyringe is excitement. the tissue damage, which includes large hemato­ mas, and internal damage, caused by the excess Delivery Methods force of the injection. Some advancements are be­ Over the years, many methods have been devel­ ing made to decrease this damage. oped to deliver the drugs to animals. At this time, A recently developed syringe is a modification there are three systems that are frequently used: the of the projectile syringe called the radio telemetry pole syringe, projectile syringe, and baits. 3 dart. This dart is a combination ofa spring loaded syringe and a radio transmitter. This helps in locat­ Pole Syringe ing animals darted in heavy cover. The dart is only available in New Zealand at this writing. 7 The pole syringe is not used that often unless fa­ There are also other less frequently used projec­ cilities are adequate to keep the animals closely con­ tiles. These are grooved darts which hold pastes and fined, which may increase the likelihood ofinjury powdered agents. They have the disadvantage of to the animal and personnel.1The lack ofconfine­ inaccuracy in the dosage and are therefore not used ment precludes its use on free ranging animals. The frequently. 1 pole syringe is, however, a good system to use in To deliver the projectiles on target, a good projec­ vaccination and antibiotic administration in captive tor is needed. The three types used most frequent­ animals. ly are the powder gun, CO2 gun, and blow-gun. The most accurate and most widely used ofthese Projectile Syringes is the powder gun. Most models use different size The most frequently used system for the deliv­ charges to vary the range, but only two companies ery ofimmobilizing agents is the projectile syringe make models with a fme adjustment for ranges from or dan. The two main components of this system 6-100 m. l The ability to vary the range is very im­ are the projectile and the projector. portant. The longer the range, the harder the im­ There are many types of syringes in use today. pact and the more damage there is to the animal. They all work on the same principle: the use of To prevent this, shorter ranges should be used some material in a closed chamber to exert a force whenever possible. to push the plunger. Another commonly used propellent is CO2 • One type ofsyringe uses compressed gas, main­ Many rifles and pistols are available and most use ly air or CO2 .1 These darts are inexpensive to ful an easily obtained CO2 cartridge. These guns have with gas, pressures can be varied, and the syringe some advantages at shorter ranges, but since they can be reused many times. However, some method use an expandable gas, variations in the tempera­ must be devised to stop leakage ofthe immobiliz­ ture and canister pressure will affect the velocity of ing agent from the needle. A plastic or silicone col­ the projectile. This is panially counteracted by the lar fitted over the opening in the needle is usually use of larger canisters and experience.

28 Iowa State University Veten'nanan A B ESCAPED AIR ~RIM INSIDE EDGE t ~ / 20 GAGE ~.: =:::>.. NEEDLE FIXING INVERTED NEEDLE PLUNGER tI_t-1-CUP BAKING SODA , ,"', ',----l', ". :., ,, ,': l ' ~ . ~ " ,. VINEGAR /

~+--MOBILE PLUNGER

LEAD DRUG WEIGHT

EPOXY BASE

FIGURE 1.19

(A) Diagram of a completely assembled blow-gun syringe (Without the tail piece). (B) Diagram showing the proper procedure for positioning the inverted plunger into the syringe tube.

Vol. 49, No. 1 The last major type of projector and the least ex= ele masses of the legs and other areas. This leads pensive to use is the blow-gun. Light weight alu­ to the collapse of the animal and eventual death minum models are available commercially, from acidosis, predation or other factors. however, inexpensive homemade versions can be T.R. Spraker has described four separate syn­ constructed out ofcommon PVC water pipe ofvar­ dromes related to capture myopathy. 7 These are the ious diameters and lengths.2o,21 They have a range peracute and acute death syndromes, ataxic my­ of up to 30 m which restricts their use to closely oglobinuric syndrome and the ruptured muscle syn­ confined animals in zoos and wild animal parks. drome. The first two are mainly the result of the Because ofthe limited range and problems with the metabolic acidosis and concurrent hyperkalemia. darts, they are used infrequently. The ataxic myoglobinuric syndrome is similar to One last delivery system that is used infrequent­ azoturia in horses and death is due to kidney and ly is the crossbow. It is cumbersome and inaccurate muscle lesions. The last syndrome, ruptured mus­ at distances greater than 40 m. It also needs spe­ cle syndrome, is the result ofmuscular necrosis lead­ cially constructed darts with extra flighting. There­ ing to rupture ofthe gastrocnemius muscles, which fore, it is only used on thick skinned animals at close eventually leads to the animal's death from preda­ range and is not recommended for use on most tion or starvation. ruminants. For example, it is used occasionally on Some attempts have been made to try to decrease elephants. the incidence ofcapture myopathy including tran­ quilizing animals with a bait before darting. Baits Although no one method has worked, the less stress The final method used to deliver immobilizing put on the animal prior to, during, and after im­ agents is the bait. Baits have been used periodical­ mobilization, the less damage there is going to be. ly in the past to immobilize animals. The advan­ There are some biochemical changes caused by tage ofthis method is that the animals do not have immobilization that are not as harmful to the to be stressed in any way before they are immo­ animal as capture myopathy. Recently, researchers bilized. The baits can be placed at an existing feed­ found that the so called hematologic normals for 24 ing station before the animals appear. Then they the white-tailed deer and some antelope2~ were can be observed from a distance until the drug takes actually stress hemograms. They found that initial effect. The only real problems with the use of baits blood samples had increased glucose, total protein are dosage and efficacy.Is (TP), and packed cell volume (PCV). Wesson et al. Most ruminants are herd type animals. If more found the PCV and TP of white-tailed deer im­ than one animal is to be captured, enough agent mobilized with phencyclidine and promazine to be must be provided to accomplish this. However, not decreased after 30 minutes and became stable at 24 all animals in the herd eat the same amount ofbait. these levels. 24 Jacobson2~ and Wesson et aI. found So some of the animals are overdosed and others glucose levels to be increased after a short delay. are underdosed. But this problem is minor com­ The increase in the glucose was thought to be due pared to that of efficacy. The only drug to show to the release of epinephrine. The increase in the any promise as a bait is diazepam. Attempts to use PCV and TP were caused by contraction of the other drugs such as succinylcholine or promazine spleen and peripheral blood pooling and protein were not successful. catabolism respectively, which are also due to the release ofepinephrine. Other researchers also found Physiological Effects of Capture the calcium, phosphorus,23 and potassium2~ to be There are many physiological and metabolic decreased after immobilization. These changes also changes that occur as a result of immobiliza­ were due to the stress of handling and not from tion. 22-2~ Not all of these changes are caused by the the drugs themselves. immobilizing agent. In fact, most changes are due to the capture of the animal. The most common Summary of these is capture myopathy. Since 1958, major improvements have been Capture myopathy is a multifaceted condition as­ made in immobilizing agents and delivery systems. sociated with capture. 22 It has been studied exten­ They have gone from the use of curare-tipped ar­ sively in the past few years, but the exact etiology rows to the present use ofpotent opioids in sophisti­ has not been discovered, Capture myopathy seems cated syringes delivered by highly accurate rifles. to be related to a metabolic acidosis caused by ex­ However, there is still a long way to go. New im­ treme exenion over a shon period oftime, This can mobilizing agents will need to have fewer side ef­ be seen histologically as necrosis of the large mus- fects, faster immobilizing action, and an easily

30 Iowa State University Veten'nanan APPENDIX 126

Dosages of Immobilizing Agents in Common Species

Species Etorphine Diprenorphine Xylazine WINarcotics Yohimbine Roan Antelope 3-4 mg 2x Etorphine 3 mg/kg 1.5-2 mg/kga Sable Antelope 3-6 2x Etorphine 3 .15a Eland 5-10 2x Etorphine 3 .2-8a Wildebeeste 3-5 2x Etorphine 1.5-3 Blesbok 2-3 2x Etorphine Gazelle 2-3 2x Etorphine 2-4 .27b Impala 2-5 2x Etorphine 3 .2-1.6b Blackbuck 2-3 2x Etorphine 3 Bison 4-10 2x Etorphine .6-1.0 .2-.3a Gaur 5-7 2x Etorphine Yak 3-8 2x Etorphine .4-1.0 Fallow Deer 2-4 2x Etorphine 5-8 .38 mg/kga Wapiti 3-6 2x Etorphine 2 30 mga .6 mg/kg White-tailed 3-6 2x Etorphine 3-5 .35-.6 mg/kga .1-.6 Mule Deer 2-4 2x Etorphine 4.4 40-100 mga .09-.4 Caribou 2-5 2x Etorphine 2 Moose 4-8 2x Etorphine .7-1.5 .15-.53 mg/kgb .15e Aoudad 2-4 2x Etorphine .62-1.5 Bighorn 2-4 2x Etorphine .8-1.0 20-50 mga .1-.3 mg/kg Pronghorn 1.5-5 mg 2x Etorphine 1-1.2 mg/kg

a with 1/2 dose of Etorphine b with. 18-.25 mg/kg Fentanyl e with .3 mg/ kg 4-aminopyradine

Species Promazines Succinyl Choline Ketamine Phencyclidine Roan Antelope .4 mg/kga 14 mg Sable Antelope .4 mg/kg

d with Xylazine.

Vol. 49, No. 1 31 administrable form. These drugs should also have 15. Tranquilli WJ, ThurmonJC, Corbin]E, Benson GJ, a fast and effective antagonist, ego yohimbine's Davis LE: Halothane-sparing Effects of Xylazine in reversal of xylazine or diprenorphine's reversal of Dogs and Subsequent Reversal with Tolazoline.] Vet PhaT'm Therap. 7:23-28. 1984. etorphine and carfentanil. 16. Roming LPG: Tolazoline as a Xylazine Antagonist in The delivery systems also need some improve­ Cattle. Dtsr;h Tierarztl Wsr;hr. 91:154-157. 1984. ment. The injury caused by the impact ofthe dans 17. Hsu WH: Personal Communique on the use ofTolazo­ must be decreased. This could significantly decrease line in ruminants. 18. Pusateri FM, Hibler CP, Pojar TM: Oral Administra­ losses especially after release. The most significant tion ofDiazepam and Promazine Hydrochloride to Im­ improvement in this area is the radio telemetry mobilize Pronghorn.] WildlDis. 18(1):48-51. 1982. syringe. Their use should significantly decrease the 19. Lochrniller RL, Grant WE: A Sodium Bicarbonate-Acid loss of animals in thick cover and make it possible Powdered Blow-Gun for Remote Injection of Wild­ to immobilize animals in areas that were bypassed life.] Wtidl Dis. 19(1):45-51. 1983. 20. HaighJC, HopfHC: The Blowgun in Veterinary Prac­ before. With these improvements alone, the inci­ tice: Its Uses and Preparation. ]AVMA. 169(9): dence of death in immobilized animals and possi­ 881-883. 1976. bly even the incidence ofcapture myopathy will be 21. Warren RJ, Schauer NL, JonesJT, Scanlon PF, Kirk­ decreased. patrick RL: A Modified Blow-gun Syringe for Remote Injection of Captive Wildlife. ] WildI Dis. REFERENCES 15(4):537-541. 1979. 22. Chalmers GA, Barrert MW: Capture Myopathy in 1. Harthoorn AM: The Chemical Capture of Animals. Pronghorns in Alberta, Canada. ]AVMA. 171(10): London, England: Bailliere Tindall. 1976. 918-923. 1977. 2. Jackson LL, Riedesel DH: Anesthesiology Lecture 23. Chao CC, Brown RD, Deftos LJ: Effects ofXylazine Notes. 1984. Immobilization on Biochemical and Endocrine Values 3. Fowler ME: Restraint. In: Zoo andWildAnimalMedi­ in White-tailed Deer.] WildI Dis. 20(4):328-332. r;ine. Philadelphia: WB Saunders. pp. 37-52. 1978. 1984. 4. Alford BT: Etorphine and Diprenorphine as Im­ 24. WessonJA, Scanlon PF, Kirkpatrick RL, Mosby HS: mobilizing and Reversing Agents in Captive and Free Influence of Chemical Immobilization and Physical Ranging Mammals. ]AVMA. 164(7):702-705. 1982. Restraint on Packed Cell Volume, Protein, Glucose and 5. Seal US, Schmitt SM, Peterson RO: Carfentanil and Blood Urea Nitrogen in Blood ofWhite-tailed Deer. Xylazine for Immobilization ofMoose (Akes akes) on Can] Zoo. 57:757-767. 1979. Isle Royale.] Wildl Dis. 21(1): 48-51. 1985. 25. Jacobson ER: Hematologic and Serum Chemical Ef­ 6. Jessup DA, Clark WE, Jones KR: Immobilization of feces of a Ketamine/Xylazine Combination When Captive Mule Deer with Carfentanil.] Zoo An Med. Used for Immobilizing Springbok. ]AVMA. 15:8-10. 1984. 183(11): 1260-1262. 1983. 7. Nielsen L, HaighJC, Fowler ME (eds).: Chemir;aI 1m­ 26. Brannian RE: Drug Dosages for Immobilization and mobiliZl1tion o/North Amenr;an Wildlife. Milwaukee: Restraint ofNon-domestic Hoofed Mammals. Unpub­ Wisconsin Humane Society Publication. 1983. lished. 8. Booth NH: Nonnarcotic analgesics. In: Booth NH, McDonald LE, (eds.): Vetennary phaT'mar;ology and therapeuftcs, 5th ed. Ames, Iowa: Iowa State Univer­ sity Press. pp. 297-320. 1982. 9. Jacobsen NK: Effects of Age and Behavior of Black­ tailed Deer on the Dosage of Xylazine. ] WildI Manage. 47:252-255. 10. Hsu WH, Shulaw WD: Effects ofYohimbine on Xyla­ zine induced Immobilization in White-tailed Deer. ]AVMA. 185(11): 1301-1303. 1984. 11. Mech LD, Del Giudice GD, Karnes PD, Seal US: Y0­ himbine Hydrochloride as an Antagonist to Xylazine Hydrochloride-Ketamine Hydrochloride Immobiliza­ tion ofWhite-tailed Deer.] Wildl Dis. 21(4): 405-410. 1985. 12. Jessup DA, Clark WE,Jones KR, Clark R, Lance WR: Immobilization ofFree Ranging Desert Bighorn Sheep, Tule Elk, and Wild Horses, Using Carfentanil and Xylazine: Reversal with Naloxone, Diprenorphine and Yohimbine. ]AVMA. 187(11): 1253-1254. 1985. 13. Renecker LA, Olsen CD: Use of Yohimbine and 4-aminopyridine to Antagonize Xylazine-induced Im­ mobilization in North American Cervidae.]AVMA. 187(11): 1199-1201. 1985. 14. Jessup DA,Jones KR, Mohr R, Kucera T: Yohimbine Antagonism to Xylazine in Free-ranging Mule Deer and Desert Bighorn Sheep. ]AVMA. 187(11): 1251-1253. 1985. Steve Servantez 32 Iowa State University Veten'nanan