The bongo antelope (Tragelaphus eurycerus) is found in the lowland forests from Sierra Leone in West Africa, through Central Africa and as far as southern Sudan in east Africa. There are also small populations also living in the highland forests of Kenya and also in the Congo. The bongo is classified as Lower Risk/ Near Threatened by the International Union for Conservation of Nature (IUCN)'s Red List of Threatened Species.1 There are two sub-species of this antelope: the Lowland (or Western) bongo, and the Mountain (or Eastern) bongo. Bongo are nocturnal, shy and elusive, with males living a solitary life and socializing only for mating purposes. The females often group together for protection in herds of up to 50 females and their young.
Bongo have a reddish-brown coat with 10-15 vertical white stripes, and a thin mane along their backs. Their legs have black and white bands and its long tail ends in a tuft. They have large ears and a tongue that is long and prehensile. The bongo has short, sturdy legs and hindquarters that are higher and more developed than the forequarters. The bongo and eland are the only tragelaphines in which both sexes have horns.1 Females weigh in at between 210 kg - 235 kg and males at 240 kg - 405 kg. Unlike other antelope species, these animals live in herds, ranging between 5 and 50 individuals foraging for food together.
Capture and/or chemical immobilization events carry inherent risks to wildlife regardless of size or species, but these risks are often more pronounced when dealing with larger species in the field, such as bongo and other hoofstock. These risks include such complications as capture myopathy, aspiration, dehydration, hypothermia, hyperthermia, respiratory depression and/or arrest and cardiac arrest. Many of these complications can come about as the direct result of chemical immobilization due to overdose, comorbidities or latent sensitivities in individual animals.
Wounds incurred during capture events must be seriously considered, even though they may seem less critical than the above complications. Wounds can occur as a result of an animal attempting to flee prior to immobilization, as it loses physical coordination during take-down after darting or, rarely, from the darts themselves.2
Physical injuries are one of the most common threats to wild animals regardless of human interventions. Animals can incur injuries that kill them directly, or injuries can affect them in ways that are indirectly fatal (e.g., reducing their ability to find food or to evade predators). Even when an animal doesn’t die as a direct or indirect result of an injury, it can be left in a permanently compromised state or with chronic pain.3 When an animal suffers a wound during a chemical immobilization event, undertaking the efforts to ensure that the animal is promptly treated so that it can make as complete a recovery as is possible is essential.
Antelope vary widely in size; for example, the small royal antelope weighs an average of about four pounds, whereas the eland weighs up to 1,800 pounds.3 At an average of between 500-600 pounds, the bongo is one of the largest African antelopes. Like all antelope, bongo are prey animals, and have evolved with instincts and behaviors designed to help them survive. Consequently, bongo will attempt to flee when approached in the field. Occasionally, this can result in injuries either before or after an animal is darted. If the approach by humans is protracted due to a long vehicle or helicopter chase, the risk of complications and injury are increased. When injuries occur, they are usually soft tissue injuries of varying severity.
Bongo have developed a number of methods to deal with predators, the most noteworthy of which is their speed and agility. If an antelope cannot evade its pursuer outright, it may try to hide in areas that are difficult to access. This is particularly true of bongo, which are forest-dwelling antelope. Should a partially anesthetized, wounded bongo disappear into the forest during a chase, it would be at extreme risk, particularly if it is lost by its human pursuers.
Most antelope injuries connected with capture events are experienced when attempting to flee human pursuers,1 and the most common injuries suffered are lacerations. While remote drug delivery via the dart itself is unlikely to result in a serious injury, darting can on occasion result in minor lacerations. Finally, in some cases an animal may need to be immobilized specifically for the treatment of a serious wound it has suffered due to other causes.
The first step will be to clean the wound. In the case of small, shallow lacerations, this can be done by flushing with a commercial povidone-iodine or other scrub solution. Deeper wounds can be flushed with povidone-iodine diluted with saline, and should generally not be sutured to allow for drainage.1 The literature recommends high volume, high-pressure irrigation unless the tissue is very delicate. The suggested lavage volume is 50 to 100 mL of fluid per centimeter of wound. Low-pressure irrigation is gentle to tissues and does not force bacteria deeper into the wound, but it does not debride as well as high-pressure irrigation, which can be performed with a pressurized fluid bag or a large syringe with an 18-gauge catheter.2
For suturing more superficial wounds that have been cleaned, a veterinarian should perform the procedure. If a veterinarian is not immediately available, non-absorbable sutures should be used.
Any antelope receiving a laceration prior to or during an anesthetic event should receive systemic antibiotics to reduce the likelihood of infection. Procaine penicillin G combined with benzathine penicillin G is a common formulation is these instances. Long-acting oxytetracycine is also frequently used to treat hoofstock that have suffered lacerations.2
Given the inherent risks associated with chemical immobilization, there is no way to guarantee that injuries will not occur, particularly under field conditions. The drug formulations currently available for immobilizing antelope and other wildlife however, have been refined to a degree that eliminates much of the risk that existed years ago. Given 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 bongo antelope in most instances.
1wwf.org.