Immobilization for Exotic Animals

In the mid-20^th Century, the chemical immobilization of exotic animals became of increasing necessity, but at that time, there were no protocols nor procedures in widespread use in the field of wildlife management. In the late 1950s, the first complete remote delivery systems became available; these were largely based upon the principles used by remote indigenous tribes that had been employing blow guns in the capture of prey (food) animals for millennia.

These days, there are myriad remote delivery systems available for chemical immobilization, and veterinarians have crafted at least as many protocols and procedures for the chemical immobilization of numerous species of wildlife. Still, it is important to note that when selecting drugs for immobilization, that there is no “cookie cutter” solution that works for all wildlife.¹ Additionally, the range of species, age, weight, sex, health and circumstances wherein veterinarians encounter exotic species (in some cases, for the first time) necessitate a great deal of flexibility in procedures and drug administration in the field.

To facilitate a smooth capture and immobilization in the field, all of those involved must have a clear understanding of their duties during the operation. This includes having a well-rounded understanding and knowledge of wildlife restraint procedures.

Regulations and Requirements in the Field

Parties who chemically immobilize, or who need to capture wild animals must be trained accordingly. It is important to realize that the capture and chemical immobilization of wildlife could be the most traumatic incident the individual animal faces during its lifetime, so it is extremely important to justify all intervention events.¹

During chemical immobilization and capture operations, a wildlife veterinarian should be consulted; often, the veterinarian will lead the team in the field. In the United States, federal regulations require that research facilities and entities, animal dealers and exhibitors have an attending veterinarian to consult and provide guidance on capture and chemical immobilization procedures and techniques.¹

The handling of all captured animals should be performed in a careful manner and as expediently as possible to ensure that no trauma, behavioral distress, or unnecessary discomfort can occur. In the U.S., the Food and Drug Administration (FDA) determines what drugs can be used on specific animal species. The FDA also requires a registration certificate for those using controlled substances which are obtained through the U.S. Drug Enforcement Agency (DEA). Personnel or field technicians who may be using or even administering controlled drugs must be working under the supervision of a certificate holder. The certificate holder is also the party responsible for keeping detailed logs, and ensuring proper storage for all drugs.² Some states also have veterinary codes which should be adhered to by anyone participating or engaging in the immobilization and capture of exotic animals via chemical means.³

Drug Delivery & Procedures

There are various methods of delivery for chemically immobilizing wild animals. Some of these include hand held syringes, jab stick or pole syringe, and projected darts or syringes. In the case of using hand held syringes, animals are often captured and restrained using nets. This method is ideal for deer, elk, goats and sheep. Jab sticks and pole syringes extend the length of the hand for administering the immobilizing drugs.¹

Projected darts and syringes are among some of the most common of modern day delivery systems. Dart guns utilize pressured carbon dioxide to deliver the dart or syringe to the animal.²

Hindlimb injections should be aimed at the rear so as to avoid the femur; forelimb shots, at the front. Although of small size, a surprising number of darts strike the spine of the scapula.⁴ Darts striking the bone are painful, can cause fractures, and may not inject the drug properly. There is also some evidence that the rate of intramuscular absorption can vary depending on site; absorptions are most rapid in the neck, the shoulder, and the hip, in that order.¹

In the zoo environment, the blow pipe is often considered a superior choice for delivery because it is silent, uncomplicated to use and maintain, and the variable distance to a moving animal can be easily accommodated by adjusting blow power, even for smaller animals.¹ Because of their light weight, limited mass, and low velocity, blow-pipe darts cause minimal impact damage and tissue trauma. All remote delivery systems require training on non-living targets in order to gain a high accuracy.

“In the field, failure of the first dart seems to reduce the chances of success for the next ones: the animal becomes alert, feels that something is going on, and keeps on moving. Animals in an advanced evolutionary status like chimpanzees or gorillas do get very angry, they start to throw every object at hand, including feces or even the loaded dart, back to the blow piper. A successful darting technique needs special skill, careful planning, knowledge of animal behavior and biology, and experience.”¹

Selection of Agents for Chemical Immobilization

Most drugs used in the chemical immobilization of exotic animals in the field are administered through intramuscular (IM) injection, which in the present day, are delivered by means of darts and dart guns.¹ An ideal drug will be in a high enough concentration, that the risk for bruising and or muscle tearing during the liquid pressure injection is minimized.

Some of the drugs typically used during chemical immobilization in the field are as follows:

Narcotic Analgesics

• Etorphine HCl – Antagonist: Naxolone Hydrochloride (HCl)
• Carfentanil citrate – Antagonist: Naxolone Hydrochloride (HCl)
• Thiofentanil A3080 – Antagonist: Naltrexone

Dissociative Anesthetics

• Ketamine Hydrochloride (HCl) – Antagonist: Yohimbe Hydrochloride (HCl)
  • Most versatile drug for animal immobilization and capture
  • Often painful with injection
  • Seizure can result when used alone
  • Schedule III

• Tiletamine Hydrochloride (HCl) and Zolazepam Hydrochloride (HCl) “Telazol or CI-744” – Antagonist: Doxapram Hydrochloride (HCl)
  • 2.5 times more potent than ketamine; wide safety margin
  • Schedule III drug

Non-Narcotic Sedatives

• Xylazine Hydrochloride (HCl) – Antagonist: Yohimbe Hydrochloride (HCl)
  • Ungulates are very sensitive to xylazine
  • Often induces vomiting
• Dexmedetomidine – Antagonist: Atipamazole
  • 10-20 times more potent than xylazine

• Butorphanol
  • Enhances xylazine effects and improves the quality of immobilization
  • Ungulates: add 0.05 – 0.1 mg/kg & Carnivores: add 0.2 mg/kg

Tranquilizers

• Acepromazine Maleate (Acepromazine) – Antagonist: None known
• Diazepam (Valium) – Antagonist: None known

Antagonists (reversal drugs)

• Naxolone Hydrochloride “Naxolone or Narcan”
• Yohimbe Hydrochloride “Yohimbe”
• Doxapram Hydrochloride “Doxapram”
• Tolazoline
• Atipamazole “Antisedan”5

When an animal is first immobilized, it should be established that the animal’s airways are unobstructed (i.e., vomit, foreign matter). The first procedure that should be performed when the animal is in hand is a physical exam. A custom exam plan should be established for each animal, including temperature, pulse and respiration.⁴

Taking part in captures using chemical immobilization can be dangerous, and any individual who immobilizes or takes part in a chemical immobilization is assuming a great deal of responsibility.¹ These should remain topmost in the minds of each team member.

¹Capture and Immobilization Procedures. Yellowstone Grizzly Project.

²Johnson, M.R. (2017). Wildlife Handling and Chemical Immobilization for Researchers and Managers. Global Wildlife Resources.

³Bookhout, T. A. (1996). Research and management techniques for wildlife and habitats (No. 639.9 R4).

⁴Jonkel, J. L. (1993). A manual for handling bears for managers and researchers. US Fish and Wildlife Service, Office of Grizzly Bear Recovery.

⁵Krieger and Arnemo, Handbook of wildlife Immobilization. (2002)

About NexGen Pharmaceuticals

NexGen Pharmaceuticals is an industry-leading veterinary compounding pharmacy, offering sterile and non-sterile compounding services nationwide. Unlike other veterinary compounding pharmacies, NexGen focuses on drugs that are difficult to find or are no longer available due to manufacturer discontinuance or have yet to be offered commercially for veterinary applications, but which still serve a critical need for our customers. We also specialize in wildlife pharmaceuticals, including sedatives and their antagonists, offering many unique options to serve a wide array of zoo animal and wildlife immobilization and anesthesia requirements.

Our pharmacists are also encouraged to develop strong working relationships with our veterinarians in order to better care for veterinary patients. Such relationships foster an ever-increasing knowledge base upon which pharmacists and veterinarians can draw, making both significantly more effective in their professional roles.

Disclaimer

The information contained in this blog post is general in nature and is intended for use as an informational aid. It does not cover all possible uses, actions, precautions, side effects, or interactions of the medications shown, nor is the information intended as medical advice or diagnosis for individual health problems or for making an evaluation as to the risks and benefits of using a particular medication. You should consult your veterinarian about diagnosis and treatment of any health problems. Information and statements have not been evaluated by the Food and Drug Administration ("FDA"), nor has the FDA approved the medications to diagnose, cure or prevent disease. Medications compounded by NexGen Pharmaceuticals are prepared at the direction of a veterinarian. NexGen Pharmaceuticals compounded veterinary preparations are not intended for use in food and food-producing animals.

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