Kudu Antelope Chemical Immobilization and Sedation

Research, zoo applications, conservation and management programs can require the capture and manipulation of kudu antelope. The development of non- and minimally invasive procedures have allowed researchers, veterinarians and management personnel to obtain certain types of data without the need to handle these animals. However, some information can only be obtained by capturing them.¹ Captures are also important for marking individuals for ecological and behavioral studies.

New technological advances such as global positioning system (GPS) collars, heat sensitive transmitters and advanced physiological monitoring equipment now allow detailed research on wildlife species such as antelope, but still require the initial capture and manipulation of individual animals.² Live captures are also required in conservation biology for animal translocations, reintroductions or population restocking.

Kudu Antelope Biology

The kudu is one of the most iconic of the African antelopes, primarily due to the male’s large, spiraling horns. The two species of kudu include the greater kudu (Tragelaphus strepsiceros) and the lesser kudu (Tragelaphus imberbis). Female kudu have short horns, while the horns of the males grow up to 1.8 meters, the longest of any antelope. The greater kudu has a larger body size, with greater kudu males being the tallest antelope after the eland.^2,3 Lesser kudus are lighter in weight and shorter in build.

The kudu’s coloration ranges from reddish-brown to blue-gray with white markings and 6 to 10 vertical white stripes on their torsos and nose chevrons. Greater kudus have white forelegs. Greater kudus are common in Eastern and Southern Africa. They are widely distributed in Southern Africa, especially in the bushveld lowlands.¹ The more elusive lesser kudu is common in the arid lowland thornbush of northeast and East Africa.³

Antelope are ruminants belonging to the family Antilocapridae and Bovidae. The pronghorn antelope, Antilocapra americana, is the only member of the former.⁴ Until the advent of potent opiates, this antelope was known to be notoriously difficult to safely capture or anesthetize.⁵ Each species of antelope has its own anesthesia recommendations with intra-species variations of dosages because of diverse individual responses to anesthetic agents.^4,5

The effects of immobilization can also considerably differ according to the capture methodology employed. In this regard, the relevant published research agrees that captures by remote delivery of immobilizing drugs via darting lower an antelope’s stress levels, thus decreasing the subsequent capture effects compared to other techniques.³ This is one of the main reasons why chemical immobilization is becoming the preferred capture method, particularly concerning large mammals like antelope.

Drugs Used for Chemical Immobilization of Kudu

There are three basic classes of immobilization drugs that are used on kudu and other antelope:

• Opioids
• Cyclohexamines
• Neuroleptics

Opioids

• The most potent drugs available for immobilization
• A major advantage is the availability of specific antagonists
• Reduced volume of drugs are typically required
• The only class of drugs practical for remote immobilization of large animals
• Potentially toxic to humans

Cyclohexamines

• Also known as dissociative agents
• Produce altered consciousness
• Dissociate mental state from environmental stimulation.
• Retain many vital reflexes
• The animal cannot walk but can move tongue, blink, swallow
• The animal may feel some pain
• Common cyclohexamines include Ketamine, tiletamine
• Cyclohexamines should not be used alone and are not reversible
• Should be used in conjunction with other drugs, such as neuroleptics

Neuroleptics

• Also referred to as tranquilizers
• Produce calmness and relaxation
• Do not cause loss of consciousness or alleviate pain perception
• Can cause death before they cause loss of consciousness
• Used in conjunction with other drugs (e.g., cyclohexamines)
• Common neuroleptics include zolazepam, diazepam, xylazine
• Common reversal agents include yohimbine, tolazoline

Combinations of these classes of drugs are often used in custom drug formulations, since lower volumes in combination can produce synergistic and safer effects that using single drugs in higher volumes. Their potency also allows for lower volumes when delivering drugs via darts.

Chemical Immobilization Methods

Less stress on kudu is likely to occur in kudu being immobilized in a zoo than in the field, since zoo animals tend to be far more acclimatized to humans and handling. In some cases, intramuscular hand injection can be used when working with zoo animals that are cooperative, or those that have been cornered in squeeze cages or enclosures. Pole syringes are also widely used, since these afford greater distance than approaching an animal for a hand injection without resorting to remote delivery systems. Drug delivery by pole syringe requires manual injection follow-through to administer drugs, as the handle is a direct extension of the plunger. With hand injection and pole syringes, larger bore needles should be used to ensure complete drug delivery.

In the field, remote chemical immobilization is usually carried out by approaching kudu and shooting a dart from a helicopter, an off-road vehicle or from the ground. While this can significantly reduce stress compared to physical capture methods, it still impacts an animal’s stress levels. Frightened kudu will have an increased heart rate, higher levels of cortisol and other stress-related biochemicals.⁴ An approach from the ground tends to produce even lower stress levels in antelope, because animals are generally less frightened than if a noisy vehicle is used. On the other hand, this is more difficult to accomplish, because it requires a closer approach with animals that are extremely alert, fast and agile.

Analgesia is essential if the animal’s skin has been breached by anything larger than a hypodermic needle. Invasive surgeries should be conducted using general anesthetics with the animal at a surgical plane; intraoperative analgesia that continues after anesthetic recovery should be provided in some form to every surgical patient.¹ For analgesic drugs, doses and frequencies of administration are more difficult to gauge, even with close clinical observation for discomfort.^5-7These observations can be even more difficult to make in the field than in a clinic or zoo setting, compounding the difficulty in such assessments.

Most opioids (Buprenorphine, Fentanyl, Butorphenol, Oxymorphone, etc.) are not effective as analgesics after 12 hours. Longer‐lasting, non‐steroidal anti‐inflammatory analgesics (NSAIDs) such as Meloxicam, Carprofen, Flunixin, Ketoprofen,etc. have longer durations of action than opioids, and can be administered in conjunction with opioids to increase potency of effect and duration of action.⁷

Reversal Agents for Kudu

Whether general anesthesia or sedation has been used, reversal agents are often required to neutralize sedation or anesthetic agents, thus allowing kudu to completely recover from being anesthetized. This is even more important in the field than in a clinic or zoo setting, because a chemically-compromised animal will be in danger of injury, predation and other hazards.

Duration of anesthesia is influenced by the drugs used, age, sex, body weight, procedure performed and the amount of stimulus during the procedure. If anesthesia is being maintained by a gas anesthetic (e.g., isoflurane), titration of anesthetic depth can be controlled almost immediately by adjusting the amount of anesthetic gas being administered to the animal. In addition, anesthetic duration can be extended for as long as the anesthetic gas is administered.^7,8 In contrast, injectable anesthetics and sedatives do not have this flexibility. Once a dose has been administered, reversal drugs should be used to bring about the desired effect.

Atipamezole is a synthetic α2-adrenergic antagonist. Developed to reverse the actions of compounds such as medetomidine and dexmedetomidine.

Naltrexone hydrochloride is an opioid receptor antagonist that is used in veterinary medicine to block receptors as a reversal agent for opiate agonists such as butorphanol. 

In recent years, great care has been taken with chemical immobilization protocols and drug development to keep these within safety margins through the use of novel anesthetics, including combinations of true anesthetics, neuromuscular blockers and tranquilizers.⁴ Thus, modern chemical immobilization techniques have dramatically reduced the side-effects of drugs and mortalities. Additionally, the use of antagonists to anesthetics is now widely employed, as this avoids the undesirable and potentially harmful effects of drugs and facilitates speedy recovery from chemical immobilization events.^4,5

Veterinary custom compounding pharmacies have widely expanded the variety, availability and efficacy of immobilizing drugs through the development of custom formulations for wild species such as kudu. One such formulation is the MKBM™ Kit, an original formulation containing:

• Medetomidine hcl 20 mg/ml
• Ketamine hcl 100 mg/ml
• Butorphanol 30 mg/ml
• Midazolam 20mg/ml

The MKBM™ Kit also includes the reversal agents:

• Atipamezole 40mg/ml
• Naltrexone 50 mg/ml

The MKBM™ Kit was developed for the chemical immobilization of numerous large exotic hoofstock species. It is an excellent choice for anesthetizing antelope, bongo, kudu, gazelle, eland, as well as other African hoofstock and certain domestic wildlife species.

Overall, the drug formulations currently available for immobilizing kudu and other large wildlife species have been refined to a degree that eliminates much of the risk that existed just a few years ago. With the right drug formulations, proper planning and safety precautions in place, experienced personnel can have the expectation of effective and incident-free chemical immobilization of kudu.

¹Brivio F, Grignolio S, Sica N, Cerise S, Bassano B (2015) Assessing the Impact of Capture on Wild Animals: The Case Study of Chemical Immobilisation on Alpine Ibex. PLoS ONE 10(6): e0130957.

²awf.org.

³britannica.com.

⁴Powell RA, Proulx G (2003) Trapping and marking terrestrial mammals for research: integrating ethics, performance criteria, techniques, and common sense. ILAR J 44: 259–276.

⁵Arnemo, Jon & Kreeger, Terry. (2018). Handbook of Wildlife Chemical Immobilization 5th Ed.

⁶Nielsen, L. Chemical Immobilization of Wild and Exotic Animals. (1999) Ames, Iowa, Iowa State University Press.

⁷Lance, W. Exotic Hoof Stock Anesthesia and Analgesia: Best Practices. In: Proceedings, NAVC Conference 2008, pp. 1914-15.

⁸Ball, L. Antelope Anesthesia. Wiley Online Library, 25 July 2014.

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.

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