Read the Spanish translation: Ecología, Anestesia y Evaluaciones Oftalmológicas Preliminares en Hiena Café (Hyena brunnea) en Namibia, Africa
There are four species of hyena; the brown (Hyaena brunnea), spotted (Crocuta crocuta), striped (Hyaena hyaena) and the aardwolf (Proteles cristata). The brown hyena is one of the largest mammalian scavengers in Africa. Males weigh 40.2±3.0 kg, and the females weigh 37.6±3.4 kg. They have powerful jaws, a long, shaggy coat, and powerful forelimbs and shoulders. The rear limbs are relatively weak in comparison. The brown hyena is a nocturnal, solitary hunter, and travels 25–40 km per night in search of food. They live in small clans composed of one male, one female, and their offspring. They communicate their territories through anal secretions pasted on vegetation. Though they are predominantly scavengers, they actively kill and consume Cape fur seal pups (Arctocephalus pusillus) and consume tsamma and Gemsbok cucumbers.
There are an estimated 5,000–8,000 brown hyenas in the wild; all populations are located in central, western, and southern Africa. The estimated Namibian population is between 800 and 1,000 individuals. The brown hyena is considered the apex predator along the Skeleton Coast of Namibia, a cool desert environment. Diamond mining, vehicular trauma, and human encroachment threaten existing populations of the hyena.
In May of 2009, as part of the Brown Hyena Research Project, four of seven attempts at immobilizing brown hyenas over a 17-day period were successful utilizing a combination of 80 mg ketamine hydrochloride and 1.4 mg medetomidine hydrochloride delivered by remote injection (Telinject, Inc. Agua Dulce, CA, USA). Clinical effects were noted within 3 minutes and all four animals became recumbent within an average of 7 minutes. All four animals were female. Clinical exam and anesthetic monitoring included physical examination, dental and oropharyngeal exam, age determination, gender determination, pregnancy status, pulse oximetry, stethoscopy, temperature, phlebotomy for banked sera samples, skin biopsy, global positioning satellite (GPS) collar placement, and photo identification. An initial select ophthalmic examination included direct ophthalmoscopy, Schirmer® tear testing, Schiotz tonometry, and fluorescein staining of the cornea. One individual demonstrated asteroid hyalosis and punctate corneal ulcers OU.
All four animals were stable throughout the procedure and were reversed with 7 mg atipamezole hydrochloride IM. Recovery occurred within 5 minutes on each animal and all four animals recovered without complication. GPS monitoring has continued to document the home ranges of each individual.
Future endeavors include evaluation of viral titers, sera chemistries, fecal hormones, internal and external parasite examination, and impact of local domestic animals on the ecology of the brown hyena.
Numerous challenges limit the successful darting of the brown hyena. The remote isolated location, government restrictions, weather, venomous animals, and a lack of infrastructure and supplies and the solitary, nocturnal nature of the hyena present nearly insurmountable challenges. These challenges inhibit a true assessment of the health and status of the brown hyena along the Skeleton Coast of Namibia.