Kudu Antelope Aspiration During Capture and Chemical Immobilization
The kudu is one of the most spectacular of the African antelopes. It has been described as one of the most striking in the antelope family, largely due to the male’s large, spiraling horns. 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 a height ranging between 1.3 and 1.5 meters (greater kudu males being the tallest antelope after the eland).1,2 Lesser kudus are lighter in weight and shorter in stature.
There are two species of kudu: The lesser kudu (Tragelaphus imberbis) and the greater kudu (Tragelaphus strepsiceros). The greater kudu is comprised of three subspecies: Tragelaphus strepsiceros, Tragelaphus chora Tragelaphus cottoni.1
The kudu’s skin coloration ranges from reddish-brown to blue-gray with white markings. They also carry 6 to10 vertical white stripes on their torsos and nose chevrons. The 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.2
Kudu typically live in herds of around 25 animals, but are often found in smaller groupings. They are primarily browsers, preferring leaves and shoots from trees and shrubs, and flowers and fallen fruits.1
Kudu and Chemical Immobilization
The veterinary care of kudu has become commonplace due to the integration of veterinary medicine in wildlife management programs, zoological collections, exotic animal ranching expansions and the private collection of wildlife species.3 As a result, wildlife managers and veterinarians are frequently called upon to chemically immobilize these animals. Vomiting and subsequent aspiration are among the more common post-sedation and post-anesthesia complications in both domestic and exotic animals. Aspiration is described as when a foreign substance enters the airway or lungs; this can apply to food, liquid, or other materials. Aspiration can give rise to serious health problems, such as pneumonia.
In the case of anesthetic aspiration, the kudu can vomit food from its stomach during a surgical procedure, which is then aspirated into the lungs. This potentially represents a large volume of food and/or fluids being aspirated, which can lead to serious complications. While postoperative nausea and vomiting (PONV) is common in humans and other mammals,3intraoperative aspiration (aspiration during a surgical procedure), is very dangerous and can prove fatal.4
Kudu Anesthesia Best Practices
Each species of antelope has its own anesthesia recommendations with intra-species variations of dosages because of diverse individual responses to anesthetic agents.5,6 These variations are factors in the risk of vomiting and anesthetic aspiration in these species, and attendant factors (e.g., stress, venue, individual animal and field conditions) must also be taken into account.
At the beginning of the last century, the primary method used for the capture of many large wild animals such as kudu was to chase them to the point of near-exhaustion—a method that was quite labor-intensive, impractical and fairly inhumane.7 With the pioneering work on the chemical immobilization of wildlife that took place from the 1950s on, chemical immobilization techniques have improved greatly through the development of increasingly efficacious drugs and equipment.
The utilization of basic veterinary knowledge can make a substantial contribution to the safety of kudu during capture and chemical immobilization. Teams that are qualified to handle wild mammals should evidence the appropriate expertise in wildlife anesthesia and should include an attending veterinarian when appropriate. A successful chemical restraint exercise is not complete until an animal is fully recovered and (in the case of field research) back in its environment. The application of appropriate pharmacological principles with an emphasis on drug reversibility will minimize the chances that the animal will be at a competitive disadvantage or inordinately disoriented following its release. Further, residual sedation and renarcotization should be avoided in the field unless absolutely necessary.5,7
Preventing and Treating Anesthetic Aspiration in Kudu
Until formulated drugs (e.g., combinations of α2-agonists such as medetomidine, detomidine, xylazine and their reversal agents) came into use in recent years, opioids were the mainstay of antelope anesthesia in wildlife and captive care.4 As with other mammals, problems encountered with certain opioids (such as etorphine or carfentanil, which have been widely used in wildlife chemical immobilization) in antelope included vomiting or passive regurgitation.
Periprocedural fasting (fasting prior to an anesthetic event) has historically been recommended by clinicians because of the suspected risk of aspiration. Unfortunately, this is very often impractical or impossible under field conditions. Additionally, much of the data on anesthetic aspiration relates to humans receiving general anesthesia, however, kudu and other antelope have been known to aspirate during procedures while under sedation and where no intubation or general anesthesia were employed.
For the prevention of anesthetic aspiration in kudu and other antelope, the available literature recommends histamine (H2) antagonists such as cimetidine, famotidine, nizatidine, and ranitidine and proton pump inhibitors (PPIs) such as dexlansoprazole, esomeprazole, lansoprazole, omeprazole, pantoprazole, and rabeprazole, which have been shown to be effective in increasing the pH and reduce the volume of gastric contents.4 Prokinetics (e.g., domperidone, metoclopramide, erythromycin and renzapride) promote gastric emptying and are also believed to reduce the risk of aspiration.6
In the event that aspiration occurs during a procedure, the first step in managing the situation is the immediate recognition of gastric content in the oropharynx or the airways.4 The antelope should be immediately positioned with the head down and rotated laterally if possible. Orotracheal and endotracheal suctioning is indicated, either before or after orotracheal intubation, depending on whether regurgitation continues and if the airway is visible. It is recommended that the airway be secured as rapidly as possible to prevent further contamination and to facilitate airway clearance.4 Flexible bronchoscopy can be used to supplement orotracheal and endotracheal suctioning; rigid bronchoscopy may be needed if particulate matter is present in the airway.4,7
3 Shaikh, Safiya Imtiaz et al. Postoperative nausea and vomiting: A simple yet complex problem. Anesthesia, essays and researches vol. 10, 3 (2016).
4Nason, K. Acute Intraoperative Pulmonary Aspiration. Thoracic surgery clinics vol. 25,3 (2015): 301-7.
5Lance, W. Exotic Hoof Stock Anesthesia and Analgesia: Best Practices. In: Proceedings, NAVC Conference 2008, pp. 1914-15.
6Ball, L. Antelope Anesthesia. Wiley Online Library, 25 July 2014, https://doi.org/10.1002/9781118792919.ch60.
7Kluger M.T., et. al. Crisis management during anaesthesia: regurgitation, vomiting, and aspiration. Quality & safety in health care. 2005;14(3): e4.
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