Bongo antelope (Tragelaphus eurycerus) are the largest and most colorful of the forest African antelopes. They are found mostly in the lowland forests of West Africa where they reside among the ground level shrubs and bushes, with smaller populations being found in the forest regions of East Africa. Bongo exhibit sexual dimorphism, with females weighing between 210 and 235 kilograms and males ranging from 240 to 405 kilograms. The females and young are chestnut red with darker legs; males start out with the same chestnut color but darken with age, eventually becoming a brownish black.
Male and female bongos have long, spiraling horns covered by a dark brown keratinous sheath. They have large, broad ears, white markings on the cheeks and legs and between 10 to 15 whitish-yellow stripes along the torso and rump. Bongos have shorter legs than other African antelopes and a body typical of forest ruminants. These characteristics help the large animals move relatively fast in their dense forest habitat.
Bongos are the only forest antelope to form herds which range from five or six bongos foraging for food together up to 50 individuals. They are both diurnal and nocturnal, although they are elusive overall. They usually stay within the bushes and shrubs of the forest during the day and only come out during the night. Bongos are grazers and browsers, typically eating leaves, flowers, twigs, thistles, garden produce and cereals. They tend to favor younger leaves, suggesting that high protein and low fiber content influence their plant choice. Bongos have also been known to regularly visit natural salt licks.
Cardiac arrest, or cardiopulmonary arrest (CPA) is an abrupt and complete failure of the respiratory and circulatory systems. The resulting lack of oxygen transport can quickly cause cellular death from oxygen depletion.1 If left untreated, cerebral hypoxia can result in death within four to six minutes of a CPA event.2 In these cases, prompt cardiopulmonary resuscitation is imperative.
In some instances, the stress of capture can increase the likelihood of cardiac arrest in bongo antelope. While under anesthesia, common causes of CPA can include vagal stimulation, unstable cardiac arrhythmias, severe electrolyte disturbances, exacerbated cardiorespiratory disorders (e.g., congestive heart failure, hypoxia)1 or a variety of comorbidities. Signs of an impending CPA event can include dramatic changes in breathing effort, rate, or rhythm, significant hypotension, absence of a pulse, irregular or inaudible heart sounds, changes in the heart rate or rhythm; changes in mucous membrane color and fixed, dilated pupils.
According to the 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 often present an increased risk of complications during anesthetic events. While carfentanil was reported as effective in many antelope captures, more recently, the combination of butorphanol and azaperone have become popular in the chemical immobilization of pronghorn. Monitoring core body temperature is essential in antelope anesthesia,3,4 and 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 mainstay of antelope anesthesia in wildlife and captive care.3
Cardiopulmonary cerebral resuscitation in bongo and other antelope involves three stages: basic life support (BLS), advanced life support (ALS), and post resuscitation care.3 The first stage involves establishing an open and clear airway, providing assisted ventilation, and performing chest compressions. If the antelope’s pulse becomes absent or weak, all administration of immobilizing drugs must be suspended and external cardiac massage should be initiated. Large veterinary patients can usually be easily and safely ventilated with a bag-valve mask,1 the caveat being that this may not be available under field conditions.
Venous access can be established by using such methods as intraosseus catheter placement and venous cutdown, in which a small opening is created in a vein to allow passage of a needle or cannula.1 Epinephrine at 0.2 mg/kg (concentrated at 1/10,000) should be given IV or intracardially (IC) while cardiac massage continues. If the animal fails to respond, 0.1 ml/kg IV or IC calcium chloride may be given. If there is still no response, the epinephrine and calcium chloride may be re-administered with 10-20 mEq IV or IC sodium bicarbonate.4
Bongo that are restored to a perfusing cardiac rhythm can experience rearrest, especially if the original cause of the CPA event has not been identified. Therefore, resuscitated patients usually should have cardiovascular and ventilatory support during the period following CPA. Mild hypothermia after resuscitation from CPA decreases cerebral oxygen demand and has been shown to improve outcomes.1