Pharmacology Biochemistry &Behavior. Vol. 39, pp. 559-561. ~ Pergamon Press plc, 1991. Printed in the U.S.A. 0091-3057/91 $3.00 + .00 Diazepam-Induced Feeding in Captive Gray Wolves (Canis lupus) TERRY J. KREEGER, .1 ALLEN S. LEVINE,t ULYSSES S. SEAL,t MARGARET CALLAHAN~: AND MARK BECKEL:~ *Department of Ecology, Evolution, and Behavior, University of Minnesota, Minneapolis, MN 55455 #Veterans Administration Medical Center, Minneapolis, MN 55417 SWildlife Science Center, Forest Lake, MN 55025 Received 16 January 1991 KREEGER, T. J., A. S. LEVINE, U. S. SEAL, M. CALLAHAN AND M. BECKEL. Diazepam-inducedfeeding in captive gray wolves (Canis lupus). PHARMACOL BIOCHEM BEHAV 39(3) 559-561, 1991.--Diazepam doses of 0.2, 0.4, and 0.8 mg/kg induced feeding in sated gray wolves in a dose-dependent manner (p<0.001). Neither 0.8 mg/kg of the benzodiazepine antago- nist, [3-CCP (p=0.36), nor 0.8 mg/kg of the benzodiazepine inverse agonist, [3-CCE (p=0.85), decreased the diazepam-induced hyperphagia. Five of 6 naive wolves (p=0.003) ate dry dog food within 15.4___1.9 min of being given 0.4 mg/kg diazeparn and freely chose dog food after the single diazepam administration. Feeding behavior Gray wolf Benzodiazepines Diazepam [~-Carbolines Eating IT has been well documented that administration of benzodiaz- epines can induce hyperphagia in laboratory animals as well as carnivores such as cats (2,5). Such increased food consumption could be due to an enhancement of appetite similar to that pro- duced by food deprivation (2) or to the attenuation of hyponeo- phagia induced by novel foods or environment (9). Although the search for the biochemical control of feeding is important for human health, animal managers have a pragmatic need for inducing food consumption in captive wild animals. It is not uncommon for wild animals, particularly predators, to be- come aphagic when captured and placed into captivity. This aphagia could be due to a hiding instinct overwhelming a drive to eat, or it could be due to the animal not recognizing a novel, human-processed food as something edible. Despite many publi- cations addressing the biochemical basis of feeding behavior, we have not found a systematic study on the pharmacological in- ducement of eating in nondomestic carnivores. We have managed gray wolves (Canis lupus) in captivity for 15 years. Several of these animals have been removed from the wild because of livestock depredation. Some of the wild-caught wolves have adapted rapidly to captivity and different foods; others have refused to eat anything except natural prey. Herein, we present experiments designed to test the hyperphagic abilities of diazepam in wild and captive gray wolves. Subjects METHOD These studies took place in east central Minnesota (Wildlife Science Center, Forest Lake, MN). A total of 12 (7 male, 5 fe- male) adult (->3 year) wolves were used, with some animals be- ing used for more than one experiment. The wolves were housed either in groups of two in outdoor kennels with cement runs, or in 0.14-ha enclosures. Wolves were routinely fed commercial dry dog food (Purina, St. Louis, MO) ad lib supplemented with vehicle-killed white-tailed deer (Odocoileus virginianus) and pro- vided water ad lib. All wolves were vaccinated annually for ra- bies, canine distemper, canine parvovirus, infectious canine hepatitis and leptospirosis. All were regularly treated for ecto- and endoparasites and maintained on heartworm (Dirofilaria im- miffs) prophylaxis (6). One week prior to testing, wolves were immobilized, brought indoors, weighed and physically exam- ined, and blood samples were taken for hematologic evaluation. Procedure The general experimental protocol was as follows. Experi- ments were conducted 14 days apart between 0830-1000 from October through January in 1989-90 and 1990-91. All food was removed from the kennels at 0730 on the day of testing. Wolves were separated within their kennels during testing, but could see and smell their mates. Drugs were given intramuscularly (IM) in the proximal hip muscles either by pole syringe or hand injec- tion. Ten min after drug administration, wolves were presented with 1.0 kg of their normal dry dog food. Humans then observed the wolves from a blind for 60 min, after which the food was removed and weighed. Data were recorded as gm food eaten per kg body weight (b.wt.). Statistical analyses were by one-way ANOVA and Fish- er's PLSD or Contingency Table Analysis at a significance of ~Requests for reprints should be addressed to Terry J. Kreeger, DVM, Ph.D., Cedar Creek Natural History Area, University of Minnesota, 2660 Fawn Lake Drive NE, Bethel, MN 55005. 559