Bongo Antelope Vomiting During Capture and Chemical Immobilization
Antelope are a diverse collection of ruminants of the families Antilocapridae and Bovidae. The bongo is a large forest-living antelope that lives in the lowland forests of Zaire and West Africa to southern Sudan. There are also small populations in the highland forests of Kenya and also in the Congo. Bongo have a striking reddish-brown coat with 10-15 vertical white stripes and a thin mane running along their back. Their legs have black and white bands and its long tail ends in a tuft. The bongo has large ears and its tongue is long and prehensile. Their horns spiral into one or one-and-half twists, with the horns of the males being longer. Females are typically more brightly-colored than males.1 Currently, all bongo are considered endangered species.
There are two sub-species of this antelope: the Lowland bongo (or Western bongo) and the Mountain bongo (or Eastern bongo). Bongo are nocturnal, shy and elusive; as such, they are seldom seen by people. They are known to disappear almost into the forest when threatened. Males live a solitary life and only socialize for mating purposes; females often group together for protection in herds of up to 50 females and their young.
Anesthetic Aspiration in Bongo
Wildlife managers, researchers and veterinarians in zoo settings sometimes need to chemically immobilize bongo to mark them for identification, to provide veterinary treatment or for relocation. Vomiting is one of the more common post-sedation and post-anesthesia complications in bongo, as well as domestic and exotic animals. Vomiting once or twice after a surgical procedure can be considered normal however, a far more serious complication involves vomiting that occurs during a procedure, as this can pose grave risks due to anesthetic aspiration.
Anesthetic aspiration involves an animal vomiting food from their stomach during a surgical procedure, which subsequently infiltrates into the lungs. This can lead to aspiration pneumonia. While modern protocols for anesthesia and sedation in wildlife are relatively safe, respiratory complications such as anesthesia-related aspiration and pneumonia can be fatal. In extreme circumstances, cardiopulmonary collapse and death can occur. The related pulmonary syndromes can include acid-associated pneumonitis, particle-associated aspiration (airway obstruction) or bacterial infection. Which of these develops depends upon the composition and volume of the aspirate.
Acute intraoperative aspiration (aspiration during a surgical procedure) is a potentially fatal complication with significant associated morbidity. Bongo undergoing thoracic surgery are at increased risk for anesthesia-related aspiration, largely due to the predisposing conditions associated with this complication. Awareness of the risk factors, predisposing conditions, precautions to decrease risk and immediate management options by the veterinarian is imperative to reducing risk and optimizing outcomes associated with this complication.2
Unfortunately, in the case of chemically immobilized wildlife, it is often impossible to perform the type of presurgical assessments that are routine and even required for human patients. Therefore, attending wildlife and research veterinarians must be prepared for the possibility of vomiting and anesthetic aspiration in bongo.
Bongo and Chemical Immobilization
The veterinary care of non-domestic hoofstock 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, research and wildlife veterinarians are required to amass the requisite knowledge associated with safely anesthetizing and handling animals such as bongo.
The sedation and anesthesia of bongo requires the knowledge the pharmacology of the drugs being used, as well as the wide variation in dose response among sub-species of these animals. Today, the quality of sedation, anesthesia and analgesia achievable in antelopes and other wildlife species has been made possible through the availability of new, receptor-specific and highly potent agonist-reversible pharmaceuticals and the improved knowledge of CNS dynamics.
According to the available literature, each species of antelope has its own anesthesia recommendation with intra-species variations of dosages because of diverse individual responses to anesthetic agents.3,4 These variations are of course factors in the risk of vomiting and anesthetic aspiration in bongo, and factors such as stress, venue, individual animal and field conditions must also be taken into account.
Monitoring core body temperature is essential during antelope anesthesia.3 Hyperthermia and subsequent capture myopathy is a commonly-encountered problem with bongo anesthesia. Intubation has been widely recommended for any anesthetized antelope that needs to be transported or anesthetized for greater than one hour. Until the more recent use of formulated drugs (e.g., combinations of α2-agonists such as medetomidine, detomidine, xylazine and their reversal agents), opioids were the go-to drugs for antelope anesthesia.4
Preventing and Managing Anesthetic Aspiration in Bongo
For the prevention of anesthetic aspiration in bongo or other antelope species, histamine (H2) antagonists such as cimetidine, famotidine, nizatidine, and ranitidine and proton pump inhibitors (PPIs) such as dexlansoprazole, esomeprazole, lansoprazole, omeprazole, pantoprazole, and rabeprazole have been shown to be effective in increasing the pH and reduce the volume of gastric contents.2 Additionally, prokinetics such as domperidone, metoclopramide, erythromycin and renzapride promote gastric emptying and are believed to reduce the risk of aspiration.5
In the case of intraoperative aspiration in bongo, the first step to successful management is the immediate recognition of gastric content in the oropharynx or the airways.1 The animal should be 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. The airway should be secured as rapidly as possible to prevent further contamination and to facilitate airway clearance.5 Flexible bronchoscopy is an important adjunct to orotracheal and endotracheal suctioning, and having a flexible bronchoscope at the ready if possible is a sound prophylactic measure. If particulate matter is present in the airway, rigid bronchoscopy may be required.2,5
2Nason, K. Acute Intraoperative Pulmonary Aspiration. Thoracic surgery clinics vol. 25,3 (2015): 301-7.
3Lance, W. Exotic Hoof Stock Anesthesia and Analgesia: Best Practices. In: Proceedings, NAVC Conference 2008, pp. 1914-15.
4Ball, L. Antelope Anesthesia. Wiley Online Library, 25 July 2014, https://doi.org/10.1002/9781118792919.ch60.
5Kluger M.T., et. al. Crisis management during anaesthesia: regurgitation, vomiting, and aspiration. Quality & safety in health care. 2005;14(3): e4.
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.
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