Drug Immobilization

Drug Immobilization
Jacob V. Cheeran

Drug immobilization or chemical immobilization is often called tranquillization in wildlife parlance. Any veterinarian knows that tranquillization is not sufficient to handle a wild animal or any intractable animal.

Man evolved on the face of the earth as hunter andgatherer. He used many methods for hunting and one ofwhich was bow and arrow. He used this technique tohunt down animals at times humans for cannibalisticactivity. But later he used a more refined word ‘war’both as an offence and defense. He improved the bowand arrow methods by different methods and one ofwhich was using poison tipped arrows. The poison wassourced both from the plants and animals as welldepending upon the local availability and the skill ofthe people. But to the pharmacologists the word arrowpoison brings to the mind the word ‘curare’, althoughdifferent tribes all over the world used arrowpoisons, including Indian subcontinent. Detailedreview of these poisons in itself is well documentedby many which is beyond our present discussion.
From pharmacological point of view sensationaldevelopment took place in early 1960s due to theadvent of remote drug delivery system and the drugsassociated with it. Tremendous advances took place inthe last four and half decades and are extensivelyused as routine wild animal management tool.

But now drug immobilization and chemicalimmobilization is used as a synonym apart from theword tranquillization. But drug immobilization will beappropriate since the chemical used should have somedesirable pharmacological property to be used forimmobilization. Hence the word ‘drug’ will be moreappropriate word to use. Now drug immobilization (DI)is used as a routine tool to restrain all species ofanimals and birds with, least stress compared to theconventional method of physical restraint. This toolis used both in the free ranging wild animals as wellas in zoo animals although these animals are inlimited escape range. This method is now used for avariety of purposes like study of diseases, variousecological studies like migration, home range andvarious other telemetric studies. Also it comes handyfor the Vet for veterinary intervention in wild andintractable animals, transport, translocation,insemination, embryo transplantation, etc. Extensivegame ranching has made the remote injection device notonly for immobilization but also for vaccination, drugadministration, marking and a host of other similaruses.

In Kerala DI is extensively used in controllingelephants in musth, which goes out of control and runberserk causing danger to life and property. Since theauthor first darted a huge tusker in musth on 24thApril 1979 the score of his team has grown much beyond 500 at present. At present there are more than half a dozen team of veterinarians working in Kerala tocontrol musth elephants by darting, which run amok dueto musth or bad treatment by mahouts. As such it hasbecome a routine veterinary activity in Keralaalthough done by a few experts in this scientific art.In central Keral elephants are used in churches,temples and mosques that too in numbers like 20-40-60etc depending upon the size of the festival.

Many of the television shows on immobilization looklike a simple operation although the truth is far fromit. It can be called as sort of veterinary anaesthesiain a most difficult situation that too on animalswhose health parameters are hardly known. Very oftenthe Vet gets only an opportunity to see the animalfrom a distance and often a part of the animal thattoo often with the help of pair of binoculars. But athrough knowledge of the dart gun, drug used,behaviour pattern of the animal, the terrain,marksmanship, team work, knowledge of local languagewhere the work is being carried out are all requiredfor successful immobilization especially in the freeranging condition.

Availability of drugs and the equipments were the mostdifficult in early days in India. This has made to dosome gun smithy work by myself. But now the equipmentsare not that difficult to obtain but the availabilityof good modern drugs are still a problem. Many of thedrugs used being narcotic the problem is much worse.

First commercially available remote injection devicesystem was “Cap-Chur”R gun marketed by Palmer Chemical and Equipment Company, Georgia US. Actually the School of Pharmacy at the Georgia developed it as a privately funded project. It was Harold C. Palmer, a US Vitamin co employee who funded it and got the patent and marketed it.

But major trials and standardization of drugs and itsdoses were done in Africa. Initially drugs tried weremuscle relaxants like curare, gallamine, suxamethoniumchloride, (succinyl choline chloride). The ganglionicblocking drug nicotine was also used. It was actuallysupplied by the Cap-Chur Company as “Cap-Chur Sol” andthe author used this (Nicotine alkaloid) for more thantwo-dozen elephants. But now nicotine is thing of pastand of historical value, although these were the drugsused by the immobilization experts used routinely inthose days.

Later several CNS depressants were tested andevaluated in South Africa under the leadership of Dr.Antonie M. Harthoorn. The development of etorphine(M99), 1963 an opioid, derivative of theophiline,heralded a new era in DI. It was effectively used inmost animals especially with the phenothiazinederivative acepromazine for large animals. Acommercial combination is also available as “ImmobilonLA” (etorphine base 2.25 mg and acepromazine HCl10/ml). It is supplied along with its opioidantagonist. But being an opioid it could not used infelids. The book “Flying Syringe”(1970) written byHarthoon gives an interesting account of hisencounters.

But Young Y.E. (ed) published a serious andprofessional book with a title” The Capture and Careof Wild Animals” (1973). But Harthoon’s classical work“ Chemical Capture of Wild Animals” (1973) (pub)Bellaire Tindal London still remains as a classicalwork on this subject. If anybody wants to understandthe basics of DI, even now this is The Book.“Restraint and Handling of Wild Animals by Fowler, M.E(1978& 1995) gives data on many animals other thanAfrican animals, as well as captive animals. “TheCapture and Care Manual” (1993): McKenzie (ed)authored by 22 wildlife experts is an encyclopaedicwork on DI. This has been revised periodically.

Phencyclidine (1978) became the drug of choice forfelids. But its psychedelic property leads to itsmisuse, which is called as ‘Angels Dust’ among drugabusers and fell into disrepute. This finally led tothe withdrawal of the drug from the market. But it isfollowed by Ketamine and subsequently by Tiletamine(Telazol R, Zoletil R). , which is marketed along withzolazepam a benzodiazepin compound to produce musclerelaxation. Muscular rigidity associated with Ketaminewas a disadvantage. This combination could overcomethis difficulty.

Fentanyl developed by Janssen Pharmaceuticals was soonfollowed by carfentanil the most potent drug everdeveloped was another milestone in the drugdevelopment uses for DI. This was followed by itscongeners like Surfentil, Alfentanil and the like. Inearly 1990s detomidine and meditomidine, two newalpha-adrenergic agonists were brought to the market,along with several antagonists for these drugs. Theserevival drugs are a big boon to the DI workers,because till then proper reversal agents wereavailable only for opioids and they being narcotic,not easy to obtain. Xylazine one of the most favoureddrug among DI experts although discovered in 1962 butintroduced into veterinary field by Bayer under thetrade name ROMPUN still remains as the most favoureddrug among vets. But it is not effective in swine andhence azaperon a butyrophenon compound is used.

During this period several development took place inthe drug delivery system and tracking of animals ofdarted animals like telemetry Global PositioningSystem (GPS) etc.

Unfortunately in India use of DI technique handled byinexperienced and unqualified persons resulted inseveral deaths and got some bad name amongconservation circles. It is our duty, theveterinarians to dispel this misunderstanding. Manylaypersons feel that all that is required in DI is atable of drugs, dose and the animals. Hence as Imentioned earlier it is our duty primarily asveterinarians and more so as pharmacologists not onlyto educate the authorities as well as offer ourservices to prove that DI immobilization is aprofessional work in spite of the inherent riskinvolved. Fortunately the present Veterinary Act isthere to support us.

If this note can instill interest in DI among atleasta a few I will be more than happy !

Recommended additional reading:
1. Handbook of wildlife chemical immobilization (By)Terry J Kreeger Pub: Author

2. Chemical Immobilization of wild and exotic animals.By Leon Nielson Pub: Iowa University Press, Ames

3. Fowler, M.E (ed) (1978&1986) Zoo and Wild AnimalMedicine (pub) WB Saunders Company Philadelphia

4. Kloss, H.G, and Lang, E.M. (ed) Handbook of ZooMedicine (pub) Van Nostrand Reinhold, New York.

5. Fowler, M.E. (ed) 1993 Zoo and Wild AnimalMedicine, Current Therapy 3rd ed. WB Saunders,Philadelphia.

6. Diseases of Exotic Animals (1983) by Wallach, J.D.and Boer, W.J. (pub) WB Saunders.

7. Text Book of Zoo Animals Care and Management. (By)Jacob V. Cheeran. 2nd ed. (Pub) International BookHouse, Patna, India.

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