Trials Of Knock-Out Drug For Hyena Successful

©Markus Hofmeyr

In a joint project led by Dr Gregory Fleming of Disney's Animal Kingdom and Dr Markus Hofmeyr of Sanparks, a new drug combination was tested on hyenas during the week of 12 to 16 March, 2007.

The project was done with the knowledge of the Medical Control Council. According to Markus, numerous drug combinations have been used to immobilise hyena in the past of which all have their own drawbacks, such as stormy induction (falling asleep) and long recovery times.

In the Kruger National Park (KNP) a recovery time of one hour or longer places an animal at various risks, which could include falling easy prey to predators.

The new combination comprises medetomidine, butorphanol and midazolam to immobilise a hyena for a period of 30 to 40 minutes. "The great benefit is that it is fully reversible with flumazenol, naltrexone and atipamezole."

Markus says they tested 18 hyena and had positive results within 15 minutes. They tested the animals' blood pressure, arterial blood gas and collected vital signs data before the animals were reversed. The combination has been used successfully to immobilise wild dogs, cheetah and lion. According to the project leaders it allows for three to five minute induction, great oxygen saturations and fast recovery times.

"If the animal is to be released into a new area, the midazolam does not have to be reversed which provides for some post-immobilised sedation. This combination can then be used for short field procedures of less than 50 minutes, if using the reversal drugs, or for longer translocations without reversing the drug combination."

The project dovetailed with two other projects on hyena in the KNP. The one, currently being drawn up by the Mammal Research Institute of the University of Pretoria, aims to investigate whether spotted hyenas behave differently around areas of intense human use and habitation, such as at Skukuza, compared to areas of lower human habitation, for example at Doispan.

Disease screening tests were drawn up for the other project for which a protocol is currently being drafted by Professor van Helden from the University of Stellenbosch to look at bovine tuberculosis in hyena and their immune response to it. According to van Helden, hyena are likely to contract the disease although they do not appear to show the clinical signs of the sickness.

All the animals that were old enough and not pregnant and lactating were kept in a boma for three days to allow the state veterinarian to perform a BTB skin test. To obtain the results of the skin tests the immobilisation had to be repeated after a few days. The hyena were then released in the area where they were captured. Markus said four hyena were fitted with special tag collars and additional collars, still being built, will be fitted later.

These hyena were captured around the Skukuza area and released there again. The two hyena, captured in the Doispan area, could not be collared as the one was too young and the other had to be freed from a snare it had been carrying around its body. "The ultimate test of the combination drug in the field showed promising results as even the compromised animal (snared hyena) responded well to the test," said Markus.

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