To save the endangered king of beasts, the first challenge is... anesthesia?

In traditional Chinese culture, the tiger is the king of beasts. It roars in the mountains and forests, and all other beasts are terrified. It can climb trees and swim, and is a first-class hunter in the animal world. Its prey includes large animals such as wild boars and bison. It is good at flying, stabbing, and locking throats, and often kills with one strike. People use the phrase "like a tiger with wings" to describe the perfection of this top predator: it can do almost anything except flying, and has no natural enemies in nature (Figure 1).

However, with the progress of human civilization, the tiger's strength is accompanied by its fragility. Tigers have tremendous strength. A Siberian tiger's forearm can produce a striking force of 1,000 kilograms and a bite force of 500 kilograms. Such strength is far beyond that of humans. However, tigers cannot survive without large enough forests. Human transformation of the natural environment has made the tiger's living space smaller and smaller. In the face of human technological progress, the tiger's various skills pale in comparison, and its number has dropped sharply due to human hunting.

Figure 1. Tigers are the top predators in nature. Image source: Reference 1

At present, the only six tiger species left on Earth, namely the Siberian tiger, South China tiger, Bengal tiger, Malayan tiger, Indochinese tiger and Sumatran tiger, are all endangered or critically endangered species. Among them, the South China tiger, a tiger subspecies unique to my country, has become extinct in the wild.

If we don't protect and save these beasts, the original mountain forest ecosystem of the earth will collapse, and the king of beasts will only exist in people's imagination. At present, people are indeed taking measures to protect them, such as establishing bases for artificial breeding and wild training of tigers, setting up nature reserves to protect tiger habitats, etc.

During the protection process, people need to perform health checks on tigers, provide medical assistance, and transfer and transport them. This requires an important premise: the operator must not be in danger of being attacked by the tiger, nor must the tiger being manipulated be in a state of shock and stress. The only way to do this is to anesthetize the tiger (Figure 2).

Figure 2. Medical assistance to an anesthetized tiger. Image source: Reference 2

As a painless medical technology, anesthesia is a masterpiece of modern human medicine. It has fundamentally changed the face of clinical medical practice such as surgery and intensive care.

Nowadays, people also want to apply the results of anesthesia to tigers, but where do they get the experience of anesthetizing tigers? Can the anesthesia time be guaranteed to be accurate? Can the tigers be scientifically monitored during the anesthesia process? Are there any adverse reactions and side effects after anesthesia? These problems are also challenges faced by researchers.

Since anesthesia is often required for captive animals in zoos, most of the experience and cases of anesthetizing tigers come from captive tigers in zoos (Figure 3).

The most studied subject in anesthesia implementation is anesthetic drugs. Chinese researchers have reported on the observation of the effect of using a specific anesthetic drug combination to anesthetize the Siberian tiger, the comparison of the effects of using four specific drugs to anesthetize three cat species, namely tigers, lions and leopards, as well as cases of adverse reactions after tigers were anesthetized with specific drugs. However, there are few systematic and large-scale studies worldwide analyzing the impact of various factors on the anesthesia effect of tigers.

Figure 3. Anesthesia of captive tigers in zoos Image source: Reference 3

Recently, a research team from the UK and Italy designed a web-based questionnaire survey, which was conducted among veterinarians, experts or other senior practitioners engaged in wildlife protection and research in the United States, the United Kingdom, EU member states, Australia, and some countries in South America, Africa and Asia. The survey was mainly conducted on the anesthesia of cats represented by tigers. The results showed that despite various practical challenges, these professionals attached importance to the preparation before anesthesia, monitoring during anesthesia, observation after anesthesia and the treatment of complications, and they had a certain consensus on the use of the preferred anesthesia drugs. Among them, 48% of the respondents reported using relatively complete instruments for monitoring, including carbon dioxide concentration monitors, pulse oximeters, electrocardiograms and arterial blood pressure monitors.

However, the survey results also showed that there are two main difficulties in anesthetizing these wild cats:

First, the shortage of more targeted and portable instruments and drugs leads to the occurrence of anesthesia complications;

Second, the anesthesia experience between different species cannot be copied. For example, the experience of anesthetizing takin may not be applicable to anesthetizing tigers. Even for cats such as tigers, lions, and leopards, there are certain physiological differences between them and they cannot be fully learned from each other.

Therefore, the research team believes that in order to better protect these endangered animals, people need to improve current anesthetic practices from a physiological and pharmacological perspective.

References:

How many fierce dogs can beat a Siberian tiger? Animal Fun Club, website: https://roll.sohu.com/a/580342195_121260361

Animal physical examination is too difficult. They have to fold and pack the animals and even use an excavator! Chengdu Association for Science and Technology, website: https://www.163.com/dy/article/EVGR3IVS0514CLPV.html

Chengdu Zoo's wild animals stick out tongues to "be cute" after being anesthetized during relocation, China Daily Asia Photo News Network, URL: https://www.chinadaily.com.cn/dfpd/2013-02/06/content_16208704_3.htm

The six remaining tigers on Earth are all endangered species, and one is already extinct in the wild. Chirp, meow, website: https://m.163.com/dy/article/DPR3U8BL0525CLNB.html

Chen Zujin, Cai Qinhui, Liang Yuzhen, et al. Comparison of the restraint effects of four anesthetics (restraint) on lions, tigers and leopards[J]. Guangdong Animal Husbandry and Veterinary Science and Technology, 2006, (04): 44-46.

Che Guicui, Zhang Enzhu, Ben Yahua. Observation on the effect of ketamine hydrochloride and sumianxin compound on continuous anesthesia of Siberian tigers[J]. Heilongjiang Animal Husbandry and Veterinary Medicine, 2008, (07): 81. DOI: 10.13881/j.cnki.hljxmsy.2008.07.085.

He Hongrong, Xu Tianci. Two cases of adverse reactions to suturing tigers with suturing[J]. Wildlife, 2011, 32(01): 34-35. DOI: 10.19711/j.cnki.issn2310-1490.2011.01.011.

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