Sirajul Hossain

Photographer & Naturalist

Death of Two Tigers: Immature Science in Immature Hands?

Posted by sirajul on February 22, 2008

Sirajul Hossain*

A leading daily newspaper published news about the death of two Bengal tigers (panthera tigris tigris) in Sunderban mangrove during research by anesthesia and radio-collaring (Prothom Alo, January 31, 2008). According to the news the first tigress was captured around end April 2005 and died six months later having the collar on. The second tigress captured in March 2006 and second time tranquilized in December 2006 to remove the collar. The BBC film crew captured this second tranquilizing sequence of near dead tigress and added it to the film “Ganges” and now showing worldwide the last scenes of that pathetic tigress. The tigress assumed dead immediately afterwards.


Sundarban – Home for The Bengal Tigers

The research project was initiated about four years back by Bangladesh Forest Department. James. L. D. Smith, Professor, Department of Fisheries, Wildlife and Conservation Biology of The University of Minnesota appointed as a consultant and Adam Barlow, a Ph.D. candidate in the Conservation Biology Program is engaged in the field research. The project effectively started its field activities in February 2005. They claimed that the idea for creating such a project was first developed during a field survey in 2001 conducted by Md. Osman Gani, Ishtiaq U. Ahmad, James L. D. Smith and K. Ullas Karanth1.

Initially the project was called “Tiger Study Project in The Sunderbans2” but later the project was addressed as “Sundarban Tiger Project1” or STP. Initially the main goals of the project were: A. To find out the home range of tiger. B. Tiger density and pray abundance in relation to forest cover. C. Tiger-human interaction. D. Change of behavior in response to tidal, diurnal and seasonal fluctuations. E. Behavior change with cubs and last kill etc. The initial objective of the project was purely scientific but after the death of the first tiger and related public reaction, the project changed its face and added some monster goals like A. Conservation capacity building. B. Creating public awareness etc.  The initial goal, Research became a part of the program. But even after inflating the project paradigm in such a vast forest like Sundarban, the project working manpower remained the same, the PhD student Adam Barlow, one forest guard, one speedboat driver and three helpers1 who had no prior experience and no considerable education. The Save the Tiger Fund and the United States Fish and Wildlife service funded the initial phase of research as the project website claimed.

collar.jpg                                                                                            The Second Tiger With Radio Collar – Photo: Screen Shot from BBC- Ganges  

On one of my many trip to Sundarban sometime in 2005 I met Adam Barlow. I came to know about his project and was delighted to know that something good is going to happen for the tigers in Bangladesh. I also found out that he is going to radio-collar eight to nine tigers in Sundarban, among them six are female and two or three male2. On my question of the method of radio collaring, I got to know that he is going to bait cows and trap them using snare and then will tranquilize by using Telazol, a general purpose anesthetic used for animal anesthesia. As a wildlife photographer and as a naturalist we always gather information on the species and try to remain informed. It struck in my mind that somewhere I read that tranquilizing wild tiger can be fatal to the animal and that’s why it is stopped in many countries and is not permitted any more. But I couldn’t recall where I got that information from. I expressed my concern to Adam and told him to check this matter from the experts.

After I came from the forest I sent a mail quarrying the effect of anesthesia of wild tiger by Telazol to one of my American friend who is working in Roche, a leading pharmaceutical company in USA. He forwarded the quarry to one of his veterinary colleague and she wrote:

“Telazol (tiletamine/zolazepam) is used in a number of wild cat species, but specifically should not be used in tigers3,4,5.  Experience has shown that tigers originally exhibit normal anesthesia during the procedure, but have neurologic signs 2-4 days later which include seizures, ataxia, and paresis4.  Two theories behind this involve recycling of the tiletamine component to an active metabolite or enterohepatic recycling via bile.  The white variant of tiger has been documented to seem especially susceptible to this effect.  Some practitioners have found that this adverse effect of Telazol is found only in Siberian tiger populations; however, the number of mixed tigers precludes reliable identification of subspecies outside the carefully documented lineage of zoo tigers.” 

I also found many other references soon about the adverse effect and reports of cause of death of tiger related to application of Telazol to wild tigers. I came in contact with Simba Wiltz, who is a Handler of big cats in Thunderhawk Big Cat Rescue, Florida. Simba got his Doctor of Pharmacy from University of North Carolina at Chapel Hill in 2004. He personally wrote me:

“It has been shown that Telazol recycles in the system of cheetahs and it is suspected that it may do the same for tigers–in fact, Tiletamine/Zolazepam should NOT be used in tigers for that very reason. You should consult the on-staff veterinarian regarding other agents available, and make sure that someone experience veterinarian is available to perform the procedure who knows emergency responses.  Still, standard of care at least in US facilities does not include Telazol for chemical control of tigers. He also noted Ketamine is notorious for causing seizures in big cats which can be lethal, proper protocol should be maintained” 

An article published in Australian Veterinary magazine, named Tiger anesthesia, by L Vogelnest, Veterinary and Quarantine Centre, Taronga Zoo, Mosman, New South Wales says:

“The use of Zoletil (same as Telazol, Tiletamine/Zolazepam) is contraindicated in tigers: recoveries are prolonged (hours to days), various neurological signs have been encountered, and there have been reports of deaths during and after its use in tigers6.”

Aust Vet J Vol 77, No 6, June 1999.  

Husbandry manual for small felids describes:

“Another commonly used drug for felid anesthesia is Telazol® (Animal Health Group, A.H. Robins Co.), (also marketed as Zoletil®, READING Laboratories), a 1:1 combination of Tiletamine HCl and Zolazepam HCl. An advantage of Telazol is its availability as a dry powder that can be concentrated from 100 to 500 mg/ml permitting small drug delivery volumes. ….  The disadvantages are occasional minor CNS signs, usually in the form of mild tremors. A re-sedation 3 to 4 days following Telazol anesthesia has been reported in some species of large felids (tiger, lion, cheetah). The cheetahs experiencing this problem originally had prolonged anesthetic episodes that required several Telazol supplements. Similar observations have been reported in some tigers. These animals usually show mild sedation with stumbling and may require supportive treatment for 12 to 24 hours before returning to normal. The use of Telazol in tigers has been replaced with Ketamine and Xylazine due to this re-sedation. If supplementation of the Telazol is required, it is advisable to supplement with ketamine (instead of Telazol) at a dose of 2-4 mg/kg intramuscularly or 0.5-2 mg/kg intravenously7.”

Nielsen L. also suggested in his book “Chemical immobilization of wild exotic animals” that Telazol should not be used for tigers and can cause death8.

walk.jpg                                                                                          Near Death tiger after 2nd time Tranquilizing – Photo: Screen Shot from BBC- Ganges  

Instead of Telazol, some experts are suggesting Ketamine and Xylazine. But as a newer anesthetic there are not much field data available. Also the protocol is more complicated for Ketamine then Telazol. Telazol is more popular to the field researchers because it has a simpler protocol and it is found in powder form which is easy to carry and preserve.

Cat metabolism and pathology is complex and not very well known yet to science. Most of the research regarding chemical immobilization is done by the veterinary and anesthesia specialists. In most cases the animal tested remains in captivity or in the zoo. For wild animal the research is very difficult and often not permitted in most countries. Which is specially true for endangered and rare species. Many of these drugs are used for emergency situations for wild animal where there is a life threat for the animal or for human. Many local people reported and In the BBC film “Ganges” it was commented that both the tiger showed abnormal behavior and there are reports of attacking people. In Eastern Sundarbn, places like Katka and Chaprakhali, where many tourists walk on the meadow and the beach or fishermen work day and night, there were never reports of aggressive behavior of tigers. Even the first tiger jumped over Dr. Tapan Kumar Dey, DFO and his team when they were trying to photograph the first tiger after collaring. They jumped on the nearby pond to save themselves in Kochikhali.

Tranquilizers work on the central nervous system of the animal. There are reports that Telazol may cause long term psychological effects to tiger. The tranquilized tiger may feel dizzy, sedated sometimes and can feel irritated or anxious some other time. Possibility of hallucination also claimed.         

with-boar.jpg                                                                                         Wild Boar is no more afraid of the dying Tiger – Photo: Screen Shot from BBC- Ganges  

Some tigers, especially Siberian tigers have shown greatly prolonged recovery and recycling of Telazol that has caused CNS signs several days after immobilization. These signs may come and go for days or weeks post-immobilization 9.”

 – Christopher J. Katz D.V.M, Anesthesia of Exotic Cats 

In 1992 during the research on Amur (or Siberian) tigers (Panthera tigris altaica). Researchers caught some tigers using Aldrich foot snares, the snared foot was swollen in all cases. They anesthetized tigers with a mixture of ketamine hydrochloride and xylazine hydrochloride instead of telazol10.

Pharmacokinetics is the process by which we know how a drug is absorbed, distributed, metabolized, and eliminated by the body. Any drug before application on any animal pharmacokinetic observation should be done. Little pharmacokinetic information is available for Telazol (Tiletamine HCl / Zolazepam HCl)11.  

Sundarban is a unique place and also the only great ecosystem in the world where Bengal tigers live in saline water system. Life of a wild tiger is extremely challenging and very much depends on the physical and psychological integrity of the animal. For zoo or captive tigers physical wellbeing is enough for her survival. But for a wild animal her physical and psychological performance together only can ensure her survival. There has not been any pharmacological research to find how the above chemicals will affect specially the Sundarban tiger that drinks salt water and eat the intestine of the kill full of mangrove vegetation. Before this research is done and proven safe, there should be no other application of those drugs on healthy tigers in the wild.

Dr. Ullas Karanth started tiger research in Nagorhole reserve forest in India using chemical immobilization and radio collaring. After the death of several tigers the Chief Wildlife Warden of India (same as our CCF) cancelled his permission for that fatal research. From then tranquilizing healthy wild tiger is not permitted in India anymore. Exception is only in case of relocation if any tiger proven to be a man-eater. Dr. Karanth and many of his foreign partners are very eager to tranquilize wild tigers and may be wants to finish their incomplete research which failed in India. The tiger radio collaring project in Bangladesh also motivated by the same group of experts who are very keen to do the same practice somewhere else where getting the research permission is easier. In an interview with the Indian famous technology magazine “Dataquest” Karanth says in June 2007:

 “The biggest issue in use of technology, say radio telemetry or chemical immobilization, is the problems of getting research permissions 12.”

The present Radio-collaring methodology of wild tigers incorporates many issues which can be harmful or lethal to the individual tiger, or to the whole or part of the population. It can even increase human-tiger conflict if it is not practiced with a lot of care, maturity and responsibility. Researchers are using live cow as bait, which can infect wild species with new disease. Amur tiger researchers say they trapped 19 tigers and all of them had swollen legs where the snare was caught10. Traps and snares can injure tiger and that could be enough for the end of their life. Applying anesthesia without proper understanding of the pharmacokinetics of the specific population can cause fatality or abnormal behavior to the tigers and which eventually can increase human tiger conflict.

We all are aware that getting adverse effect information about wild animal research on any drug or procedure is very difficult. Expert community in wildlife research is small and everybody knows each other. Only a few organizations are funding and nobody wants to say negative words towards friends and colleagues. Almost everywhere the wild animals are government’s property and protected by the state law. If any wrong things happen somewhere, the news does not go very far, officials need to save themselves too. This creates misconceptions for the others about choosing the proper method if it does not fall in his own discipline of knowledge. Often experts remain silent about a wrong idea fearing that criticism can make them isolated in the community.

Chemical immobilization techniques and its protocols for wild animals are still immature science. Many species of Asia and those which are special like saline water tigers can not be experimented without proper knowledge of the drug and its interaction. For any chemical immobilization a licensed veterinary doctor with specific knowledge on the species and the pharmacology should be present at the field and should be officially responsible for the status of the animal.    

There are some experts who are very much interested in gizmo science. They think the use of GPS and radio telemetry or any other high-tech gadget will solve every problem. Thick canopy like sundarban may also impair GPS function and can put a lot of void in data. If the tiger shows prolonged CNS signs and abnormal behavior with the effect of the drug, the acquired data by the collar will be vitiated. Any planning or strategy implemented based on those erroneous data can cause harm to the whole population. The same research can be done with camera trapping (like Trail Master). Camera trapping is allowed everywhere and used worldwide without any harmful effect on the species for similar research.    


1          STP Website, 

2          Project Flyer published by Forest Department and MoEF

3          Wack, R. Felidae. Fowler ME, Miller ER eds. Zoo and Wild Animal Medicine, 5th ed.

            WB Saunders, Philadelphia. 2003.

4          Curro, TG. Large Cat Anesthesia. Accessed March 15, 2004.

5          Miller M, Weber M, Neiffer D, et al. Anesthetic induction of captive tigers (panthera

            tigris) using a medetomidine-ketamine combination. J Zoo Wildl Med. 34(4):307-8, 2003.

 6          Tiger anesthesia, by L Vogelnest, Aust Vet J Vol 77, No 6, June 1999. 

7          Mitchell Bush et. al, Husbandry manual for small felids, Ch.3, by, National Zoological Park Conservation & Research Center, Published by Disney’s Animal Kingdom, Lake Buena Vista, FL

8          Nielsen L., Chemical immobilization of wild exotic animals. Iowa State University

            Press, Ames, 1999.

9          Christopher J. Katz D.V.M, Anesthesia of Exotic Cats,


10        John M. Goodrich, et. al.Capture and Chemical Anesthesia of Amur (Siberian)

            Tigers, Wildlife Society Bulletin, Vol. 29, No. 2

11        Donald C. Plumb, Pharm D, Veterinary Drug Handbook, , Blackwell Publishing,


12        The Last Roar, Dataquest, India, Wednesday, June 27, 2007,   

*Published in The Daily Star, Thursday, February 22, 2008


8 Responses to “Death of Two Tigers: Immature Science in Immature Hands?”

  1. Catherine Wood said

    I couldn’t agree more. As a wildlife veterinarian, I was shocked and saddened to read on the BBC that telazol was being used in wild tigers after American zoo veterinarians knew to stop using the drug in tigers almost 2 decades ago. Not to use telazol was probably the first thing I learned about tiger medicine in college. Thank you for posting this. Also, if you could use contact information of any diplomates of the American College of Zoological Medicine to help make your point, please contact me.

    Seal, U. 1990. Adverse reactions to Telazol in tigers. American Association of Zoological Parks and Aquariums Communique May 1990:19.

  2. Ruhul Amin Rushd said

    Thanks. It’s very informative and excellent write-up.

  3. spencer said

    i think this is good info

  4. Moni said

    Thanks to the author for his excellent write-up..we the Bangladeshi vets still have a very long way to go..learned many things from the article.

  5. To
    Mr. Sirajul Hossain
    I’m following your “Death of two tigers:The other
    agendas?” and related articles. Fantastic… Finally I got one similar thinking human being on the earth regarding protesting against wrong research on tigers. In Karnataka since 1990 I’m opposing the research methods of Dr. Ullas Karanth. Because he also killed 11 tigers in name of research like your Mr. Adam. But the issue got a entirely different turn, where officially it was declared only 5 tigers were dead. In that period Mr. R Sukumar(See, Nagarhole Tiger Controversy, Current Science,Vol.59, No.23, 10-Dec-1990) and his caste friends defended him, adding to that upper cast Media Politics also supported him by all means. Mr Karanth and his gang said that all these tigers were dead because of the territorial conflict and not because of their research techniques. Above all these politics people and the government knew what exactly was the fact.

    As a result government cancelled his research permission and came
    forward to take legal action against him.But miracley the entire dramawas ended happily.
    According to an anecdote, Dr. Ullas Karanth, the only son of Dr.
    Shivaram Karanth, a renowned writer and Jnanapeetha award winner
    inevitably entered the scene.Dr. Shivaram Karanth had a talk with one of the most influential lady environmentalist of Delhi. Later she entered the scene and took control over Karnataka Forest department. Overnight Ullas Karanth was out of the scene without any damages.

    Later on he filed a petition in the High Court seeking permission for his further research. Regarding this Forest department filed an affidavit against Ullas Karanth.But ironically BJP (a communal minded party) led state government filed another affidavit in favour of Ullas Karanth (Do you think that caste politics can play this kind of vital role even in conservation of tigers in India?). Still the judgement is pending. Regarding this issue an article was published in a leading national daily ‘The Hindu’ on oct 14, 2010.

    Dr.T S Vivekananda

    [I’m an environmental activist and writer/columnist in
    Karnataka/Kannada.and the Fonder Director of the “Jeevamandala”, an
    cadre based environmental organisation]

  6. Dr. Zahed Mohammad malekur Rahman, Veterinary Surgeon, Forest department, Bangladesh said

    As a wildlife veterinarian, I don’t agree with their drug selection which is using for tiger immobilization. Telazol/Zolatil (Tiletamine+Zolazepam) is not the suitable drug for tiger immobilization. I surprised, when I knew in last 2007 from WTB regarding the matter. It is usually used for some specific member of cat family and for wild pig. According to my experience and study, Hellabrunn mixture (Ketamine + Xylazine) or ketamine combined with meditomidine; are the perfect choice for the safe immobilization tiger.

    • Dr. Siva Nathan said

      Dear Dr. Zahed, Please advise the dosage of Ketamine/meditomidine for immobilization of Siberian Tigers, Bengal Tigers and African Lion/lioness. I have 5 of them to relocate. Thanks

  7. Dr. K. P. Singh, Senior Wildlife Biologist, CWFH , M.P. Pashu Chikitsa Vigyan Vishwa Vidyalya Jabalpur, India

    The article is comprehensively reviewed and could be the part of precautionary measures during tiger immobilization.
    Due to involvement in the Wildlife Health Management in the country since 1996, I would say the sedation is mandatory process for wild Felids either for treatment or translocation of problematic animals . However, immobilization must be conducted by registered and experience wildlife health management expert. Because, even pet veterinarians have lacunae with drug doses during physiology in stress in wild animals which is entirely different from domestic animals and only experts-experienced WHM- VET can presume the genuine doses, anti dots and post operative care within existing circumstance.The excitement and passion are less considerable approach in wildlife, that is why, enthusiastic efforts while innocently conducted, would damage the precious life of the wild animals.
    Tiger :The patrolling guard of the forest

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