Kudu Antelope Sedation
The kudu is one of the most stunning of the large African antelopes. The name “kudu” is derived from the Afrikaans language (The Afrikaans term “koedoe” being a combination the words for zebra and deer).1 There are two species of kudu; the lesser kudu (Tragelaphus imberbis) and the greater kudu (Tragelaphus strepsiceros). The greater kudu also has three subspecies; T.s. strepsiceros, T.s. chora, and T.s.cottoni.2 One of the kudu’s most striking features is the male’s large, corkscrew horns.
The greater kudu is the larger of the two species, with a height of between 1.3 and 1.5 meters. Females are smaller and shorter, with an average height and weight of 1.2 meters and 170 kg. Kudus are found in Eastern and Southern Africa, with a wide distribution in Southern Africa. They are also found in the East African regions of Kenya such as in the Tsavo National Park, Tanzania’s Serengeti National Park, and the horn Africa region of Ethiopia and Somalia.2 Many free-ranging kudus have retreated to mountainous woodlands due to human activities in the African lowlands. Kudu live in herds of approximately 25 individuals, although smaller groups of two to three females with their calves are also frequently sighted.
Anesthesia vs. Sedation
Depending on circumstances and the invasiveness of procedures to be performed, veterinarians and wildlife managers are often faced with the choice between employing anesthesia or sedation when chemically immobilizing kudu. Anesthesia is defined as a pharmacologically-induced, reversible state of amnesia, analgesia, loss of responsiveness, and loss of skeletal muscle reflexes. Sedation is a drug-induced depression of consciousness during which an animal cannot be easily aroused, but may respond following repeated or painful stimulation.3 The advantages of sedation over general anesthesia typically focus on patient safety.
The comparative safety of sedation over general anesthesia in human patients is well established. Sedation is associated with decreased risk in other species as well; therefore, sedation is often considered in place of general anesthesia whenever possible.3 Until the advent of potent opiates, the pronghorn antelope (for example) was known to be very difficult to safely capture or anesthetize.4 The focus on the use of sedation in exotic animals such as kudu is a direct result of the perception of greater anesthetic risk in these patients, especially in those that are ill or debilitated.
Capture and Chemical Immobilization Risks
The term “chemical immobilization” covers both anesthesia and sedation. There are many physiological and metabolic changes that occur as a result of chemical immobilization, not all of which are directly caused by the immobilizing agents. Many of these changes are due to the stresses associated with the capture of an animal itself, the most serious of which can bring about a condition called capture myopathy. This is thought to be related to a metabolic acidosis caused by extreme exertion over a short period of time, resulting in necrosis of the large muscle masses of the legs and other areas. This leads to the collapse of the animal and eventual death from acidosis, predation or other factors.5 Since all antelope are prey animals and have evolved with instincts and behaviors gauged to help them survive, this is an inherent risk in the capture of kudu.
Other risks associated with the capture of kudu include aspiration (vomiting), hypothermia, hyperthermia, frostbite, bloat, respiratory depression/arrest and cardiac arrest. Each species of antelope has its own anesthesia recommendations with intra-species variations of dosages because of diverse individual responses to anesthetic agents,6,7 further complicating the formulation of procedures for their immobilization.
Disadvantages of sedation (as opposed to anesthesia) can include incomplete elimination of patient movement, patient semi-awareness, and lack of complete analgesia. These can be overcome with careful dosing and monitoring, effective patient handling and efficient use of analgesics when handing or procedures are expected to produce discomfort.5 The American College of Veterinary Anesthetists (ACVA) has published recommendations for monitoring animals that are sedated without general anesthesia:
- Palpation of pulse rate, rhythm and quality
- Observation of mucous membrane color and CRT
- Observation of respiratory rate and pattern
- Pulse oximetry Supplemental oxygen, and endotracheal tube (where applicable) and materials to obtain vascular access should be readily available3
Drugs Used for the Sedation of Kudu
Sedatives produce calmness, loss of aggression and loss of alertness which are generally required during transportation. In this condition, animals are not immobilized fully and can be aroused by various stimuli. Therefore, sedatives are usually used singly for only very minor procedures, or as adjuncts to dissociative anesthetics for hastening smoother induction and to reduce the quantity of anesthetic for achieving more effective immobilization. The synergistic effect of tranquilizers and anesthetic is far greater than the individual effect of either of two drugs with respect to smooth induction, good muscle relaxation and smoother recovery.7
Sedatives commonly used in veterinary medicine include drugs such as midazolam, alprazolam, amitriptyline, buspirone, clomipramine, dexmedetomidine, diazepam, fluoxetine, lorazepam, paroxetine, sertraline, or trazodone. Acepromazine is also widely used in veterinary medicine as a sedative.
Midazolam is often used in human and veterinary medicine for the purposes of pre-anesthesia and sedation and has a wide margin of safety in many species. When combined with an opioid, its effects are synergistic, allowing a reduction of the amount of either drug.4 Dosages most commonly used are 0.5-10 mg/kg, combined with an opioid (butorphanol, buprenorphine, hydromorphone, other). Effects are variable, from slight decrease in activity to lateral recumbency. These effects are likely related to species variability in response and the varying dose rates suggested for different species/groups. In all cases, patients are still able to react to handling and noxious stimuli.3,7
When midazolam is used alone, sedation may be adequate in ruminants, camelids and several other species. When used in combination with other drugs (e.g., opioids, ketamine, acepromazine, dexmedetomidine), midazolam provides more reliable sedation. It should be noted that use of sedation and manual restraint alone is inappropriate for any procedure expected to produce discomfort. In mammals, additional sedation can be provided with sub-anesthetic dosages of ketamine, 2-7 mg/kg, or alfaxalone, 1 mg/kg IM. If additional immobilization is essential, low concentrations of inhalant gas can be considered.3
Drugs used for the sedation of kudu may vary depending upon the preference and experience of the veterinarian or wildlife management personnel. The available literature suggests that dosing higher when in doubt is in fact far safer than dosing conservatively, in that there is more risk to a partially-immobilized animal and to human handlers than there is to a heavily-dosed animal.6,7 This is due to the relative safety of modern drug formulations, which allow for much more latitude in dosing without putting an animal’s health or life at risk.
3Lennox, A., DVM. Sedation as an Alternative to General Anesthesia in Exotic Patients. Delaware Valley Academy Veterinary News, March, 2010.
4Balko, J. et al. Advancements in Evidence-Based Anesthesia of Exotic Animals. Veterinary Clinics: Exotic Animal Practice, Volume 20, Issue 3, 917 – 928.
5Sontakke, S., et. al. A Manual on Chemical Immobilization of Wild Animals. European Journal of Wildlife Research, 36 pp 34-41.
6Arnemo, Jon & Kreeger, Terry. (2018). Handbook of Wildlife Chemical Immobilization 5th Ed.
7Ball, 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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