Investigation Of Anaesthetics For Clinical Applications In Wild Animals

In the zoo, chemical immobilization and anesthesia are necessary when wild animals are needed to removal, insemination, medical examination, disease diagnosis and treatment or operation. The principles for animal immobilization and anesthesia are to decrease stress and accidental injuries as greatly as possible, ensuring security for personnel and animals.Because there are many kinds of wild animals in the zoo, each kind of animals has special tolerance or sensitivity for a certain anesthetics. We should choose a drug that is suitable for immobilizing and anesthetizing a wild animal according to properties of the drug and the animal,respectively.Up to now, there have not been an ideal drug for the need of all wild animals' anesthesia. Because there are many anesthetics used in wild animals, each drug shows diverse effect in different animals. By long-term clinical practice, each zoo has accumulated a lot of experience in animal anesthesia, but there are short of uniform views.The writer investigated anesthetic datum of 53 species 3472 heads of animal in 32 domestic zoos, consulted a great mass of reference documents and combined with his clinical experience in wild animals, screened out suitable anesthetics and their dosage for each wild animal. It provided references for secure and effective anesthesia and immobilization for wild animals.The chemical agents employed for animal immobilization and anesthesia are divided into two broad categories: (1)the neuromuscular blocking drugs, which act predominantly on the neuromuscular junction of skeletal muscles or the motor end-plates and cause immobilization through paralysis. The most ancient agents are curare and d-tubocurarine,gallamine and Succinylcholine are still used currently. With the advent of the safer and more effective centrally acting drugs, the use of neuromuscular blocking drugs for mammalian immobilization has declined sharply, but they are still used in reptiles; (2) the central acting drugs, which act primarily on the central nervous system and cause immobilization through CNS depression. It includes: (a) analgesics, such as alphaz-adrenergic agonists and opioids; (b) neurolep-tics, such as phenothiazines, benzodiazepines and butyrophenones; (c) narcotics, such as cyclohexamines.To reduce untoward reactions of drugs and improve anesthetic effect, some drugs of different pharmacological property such as tranquilizer, hypnotic, depolarizer and sedative are often used in succession or together. It is called compound anesthesia.Antagonists are drugs that can effectively antagonize depression for CNS and other side effects caused by anesthetics. It can overcome undesirable effect and com-plications., accelerate recovery of physiologic function and detoxicate if anaesthetics are overdose.According to survey, we found there were eleven anesthetics used in wild animals in domestic zoos: the mono-agents include: Ketamine, Xylazine and Xylidlnothiazol; thecompound agents include: Baodingning, Miannaining, Sumianxin, ketamine+diazepam,ketamine+Miannaining, ketamine+Sumianxin, Saiantong and Large Animal Immobilon. All of these anesthetics, depending on our investigation and analysis were suitable for immobilization and anesthesia of wild animals as follow, respectively:1 For herbivores:Cervidae: miannaining first, the recommended dose was 1.5～2.2mL/100Kg, but for fallow deer and sambar the dose was higher(2.2～3.2mL/100Kg). Saiantong was secondary, the recommended dose was 3～4mg/Kg, for sambar the dose was higher(6.5-7.2mg/Kg);Bovidae: Large Animal lmmobilon, the recommended dose was 12～30/μg/Kg;Miannaining(1.8～2.3mL/100Kg), Xylazine(2～2.3mg/Kg)and Xylidlnothiazol(0.4～0.6mg/Kg)could also been used for takin and yak;Equine: Large Animal Immobilon(10～17/μg/Kg)and Baodingning(2.3～4.0mL/1OOKg);Camelidae: Miannaining(wild camel 0.5～0.7mL/100Kg,guanaco 0.8～1.4 mL/100Kg), xylazine(2.2～3.0mg/Kg)and Saiantong(2.7～3.2 mg/Kg);Large wild herbivores: Large Animal Immobilon(asian elephant 1.87～2.20μg/Kg, african elephant 3μg/Kg, giraffe 7.50～11.76μg/Kg ), Miarmaining could also be tried to use for elephant.2 For carnivores:welidae and ursidae: Saiantong and miannaining. The recommended dose of Saiantong for felidae was 1.8～3.6mg/Kg, for ursidae was 2.9～4.7 mg/Kg; and miannaining for felidae was 1.9～2.6mL/100Kg, for african lion the dose was higher(2.81±0.42 mL/100Kg), for ursidae was 1.8～3.1 mL/100Kg; Canidae:Saiantong, miannaining and Sumianxin. The recommended dose of Saiantong for lynx was 2.89±0.32mg/Kg, for wolf was 5.38±0.50 mg/Kg; miannaining for lynx was 3.25±0.64 mL/100Kg, for wolf was 6.14±0.75mL/100Kg; and Sumianxin for lynx was 7.95±3.56 mL/100Kg, for wolf was 7.52±1.78mL/100 Kg;Giant panda: Ketamine(5.22±1.86mg/Kg), ketamine+diazepam(Ket:5.18±1.01mg/Kg, diazepam:0.2 mg/Kg), Saiantong(2.38±0.42 mg/Kg)and Miannaining(1.45±0.20mL/100Kg)could be all used;Lesser panda: Ketamine and Saiantong. but should be given a large mount of dosage(12.90±2.53 mg/Kg and 6.37±1.85 mg/Kg).3 For primates:Ketamine and its compounds were effective anesthetics for primates. The therapeutic index was high and induction time is short. The recommended dose of Saiantong was 1.8～3.0mg/Kg, ketamine+Miannaining was 1.07～5.48 mg/Kg+0.008～0.024 mL/Kg, ketamine+Sumianxin was 5mg/Kg+0.05mL/Kg, and ketamine is 4.8～10.9mg/Kg.If miannaining was used for primates, depression of respiration and circulation was obvious. Further more, recovery was often slow though an animal is given an antagonist drug.4 For the other wild animals:MarsupiaIia and pinnipedia: Ketamine and ketamine+diazepam. The recommended dose of ketamine for kangaroo was 18.57±2.26 mg/Kg, for seal lion and seal was 4～10 mg/Kg, and ketamine+diazepam for kangaroo was Ketamine 15 mg/Kg+diazepam 0.9 mg/Kg, for seal was 4.67±0.82 mg/Kg+0.22+0.06 mg/Kg;Large birds:miannaining first, the recommended dose of miannaining for ostrich was 2.32±0.18 mg/100Kg, for emu was 3.14±0.51 mg/Kg, and ketamine+Sumianxin(ostrich 15.56±3.24 mg/Kg,0.24±0.04 mL/Kg), ketamine+diazepam(Ket20～25 mg/Kg+0.85 mg/Kg) and ketamine(ostrich 24.36±3.20 mg/Kg,emu 27.95±3.11 mg/Kg)were secondary.Because of the increased release of norepinephrine in stressed, agitated, or very excited animals, the alpha2-adrenergic agonists did not produce satisfactory immobilization when animals were in such states. So alpha2-adrenergic agonists were seldom used alone and mostly in combination with opioids or cyclohexamines for wild animals.When using miannaining for animal immobilization, the first dosage should be sufficient, the effect of supplemental drug was not so good. The induction should be quiet and avoid stimulation. Nearly clinical application of miannaining found if it was used in an animal (especially in Cervidae and ursidae) for many times, the animal can produce tolerance for the drug and the dosage increased gradually.If using ketamine alone, the animals usually showed poor muscle relaxation, cause muscle rigidity or twitching even convulsion.Moreover the duration of anesthetic time was short, and is not fit for long-term operation. So it was usually combined with neuroleptics such as diazepam and xylazine.