Effects of ketamine on carfentanil and xylazine immobilization of white-tailed deer (Odocoileus virginianus).

Using a crossover design, the effects of the addition of ketamine to a previously determined optimal hand-injected immobilization dosage of carfentanil/xylazine were evaluated in 11 adult white-tailed deer (Odocoileus virginianus). Two i.m. ketamine dosages were evaluated: 0.15 mg/kg (low ketamine) and 0.30 mg/kg (high ketamine). Each deer was immobilized twice 2 wk apart. Inductions were video recorded and reviewed by observers, who had been blinded to drugs and dosages, who rated qualitative aspects. There were significant (P < 0.05) dosage-dependent decreases in heart rate, SaO2, and arterial pH, and a significant dosage-dependent increase in PaCO2. Induction times with both dosages were more rapid (mean 2.3 +/- 0.9 min for low ketamine and 2.3 +/- 0.6 min for high ketamine) than those reported for the same carfentanil/xylazine dosage used without ketamine. Mean quality ratings, though improved compared to those reported for carfentanil/xylazine alone, were considered "undesirable" for both dosages. Hyperthermia (temperature > 41 degrees C) was noted in 13 of 22 immobilizations. Arterial pH and PaO2 increased significantly from 10 to 20 min postrecumbency, but acidemia (pH < 7.3) was present throughout immobilization periods for all deer. There were ketamine dosage-dependent increases in respiratory components of this acidemia compared with that associated with carfentanil/xylazine alone. Possible hypoxemia was present at both sampling times for both groups, while hypercapnea (PaCO2 > 60 mm Hg) was present for the high-ketamine group only. Reversal times for naltrexone and yohimbine were rapid (mean 2.9 +/- 0.7 min for low ketamine and 3.3 +/- 0.8 min for high ketamine), with no evidence of renarcotization. Although the addition of ketamine to carfentanil/xylazine caused faster inductions and improved induction qualities, it also produced an increased incidence of hyperthermia, acidemia, hypoxemia, and hypercapnea. Supplemental oxygen and close monitoring of body temperature is recommended when using this immobilization regimen.

Determination and evaluation of an optimal dosage of carfentanil and xylazine for the immobilization of white-tailed deer (Odocoileus virginianus).

Using an iteration method, optimal hand-injected immobilization dosages of carfentanil/xylazine (CAR/XYL) were determined for 13 adult white-tailed deer (Odocoileus virginianus). Deer were temporarily restrained in a squeeze chute and were repeatedly immobilized one to four times at 2-5-wk intervals from December 2002 to March 2003. A fixed ratio of 1 mg CAR:10 mg XYL intramuscularly was used, increasing or decreasing the dosage until the optimal dosage (defined by an induction time < 3 min and PaCO(2)< 60 mmHg) was reached for each animal. Inductions were video-recorded and reviewed by observers blinded to drugs and dosages, who rated qualitative aspects of each induction. There were significant (P < 0.05) dosage-dependent decreases in induction time, time to first effect, PaO(2), SaO(2), and arterial pH, and significant dosage-dependent increases in PaCO(2) and quality ratings. The median optimal dosage (mOD) was 0.03 (range, 0.015-0.06) mg/kg CAR+0.3 (range, 0.15-0.6) mg/kg XYL. Induction times using the mOD were rapid (median 3.0 min [range, 1.8-10.0]), but quality ratings were considered undesirable for nine of 13 deer. Increased rectal body temperatures of 40.6+/-0.5 C (mean +/- SD) were noted in all deer and hyperthermia (T > 41 C) was noted in three. There was a positive correlation between body temperature and induction time (r=0.44). Heart rates significantly decreased from 5 to 15 min postinduction and remained decreased at the 20-min reading; there was occasional bradycardia. There was a significant increase in pH from 10 to 20 min postinduction, but metabolic acidemia (pH<7.3) persisted throughout the immobilization periods for all deer. Possible hypoxemia (SaO(2) and SpO(2)<90 mmHg but PaO(2)>60 mmHg) was present after induction, while hypercapnea (PaCO(2) > 60 mmHg) did not occur. Reversal times with naltrexone and yohimbine were rapid (mean 3.7+/-1.5 min) and uneventful, with no evidence of renarcotization. Although the median optimal dosage produced rapid inductions, no respiratory depression, complete reversal after antagonist administration, and no renarcotization, negative attributes included elevated body temperatures, acidemia, and undesirable induction qualities.

Thyroid cystadenoma, colloid goiter, and hypothyroidism in an American black bear (Ursus americanus).

A 178-kg, 14-yr-old captive female American black bear (Ursus americanus) was examined because of lethargy, inappetance, obesity, and alopecia. Serum chemistry and complete blood count values were within normal limits. Based on serum levels for total thyroxine (T4), free T4 by equilibrium dialysis (fT4ED), and canine thyroid-stimulating hormone concentrations, using assays validated for domestic dogs, hypothyroidism was diagnosed presumptively, and therapy with levothyroxine sodium (0.022 mg/kg p.o. b.i.d.) was initiated. Haircoat, body weight, appetite, and activity level improved within 30 days. The levothyroxine dose was decreased twice (to 0.018 mg/kg p.o. b.i.d. and then to 0.011 mg/kg p.o. b.i.d.) during the course of treatment based on monitoring of serum T4 and fT4ED concentrations. After euthanasia for severe refractory lameness, postmortem examination revealed bilateral thyroid lobe enlargement and a fluid-filled cyst within the right lobe. Histologically, colloid goiter was present in both lobes, and a follicular cystadenoma had replaced one third of the cranial pole of the right lobe. The goiter and cystadenoma likely contributed to the hypothyroid condition in this bear and fT4ED was a more sensitive indicator of hypothyroidism than was T4. The recommended canine dosage of levothyroxine may be too high for the treatment of hypothyroidism in American black bears; 0.011 mg/kg p.o. b.i.d. may be a more appropriate dosage.

Blastomycosis in nondomestic felids.

Blastomycosis was diagnosed in six nondomestic felids from eastern Tennessee, including two Asian lions (Panthera leo persicus), one African lion (Panthera leo), one Siberian tiger (Panthera tigris), one cheetah (Acinonyx jubatus), and one snow leopard (Panthera uncia). Clinical signs included lethargy, anorexia, weight loss, dyspnea, sneezing. ataxia, and paresis. Variable nonspecific changes included leukocytosis, monocytosis, moderate left shift of neutrophils, moderate hypercalcemia, hyperproteinemia, and hyperglobulinemia. Thoracic radiographs revealed interstitial and alveolar changes, consolidation or collapse of a lung lobe, bullae formation, and a pulmonary mass. Agar gel immunodiffusion (AGID) serology for Blastomyces dermatitidis was performed in five felids and was positive in three. The tiger had cerebral blastomycosis and was positive for AGID serologic tests of both cerebrospinal fluid and serum. One percutaneous lung aspirate in the snow leopard and one bronchial aspirate in an Asian lion demonstrated B. dermatitidis organisms. whereas tracheal wash samples and a nasal discharge were nondiagnostic in others. Treatment with itraconazole was attempted in four cats. The tiger improved before euthanasia, whereas the others did not survive beyond initial treatments. In four felids, B. dermatitidis was found in the lungs and tracheobronchial lymph nodes associated with a florid pyogranulomatous reaction; the tiger had a pyogranulomatous encephalomyelitis, and the cheetah had a single pulmonary granuloma. Thoracic radiography, cytologic examination of lung lesion aspirates, and B. dermatitidis AGID serology should be performed on clinically ill zoo felids in endemic areas to rule out blastomycosis.

A comparison of carfentanil/xylazine and Telazol/xylazine for immobilization of white-tailed deer.

October 2001 to January 2002, captive free-ranging white-tailed deer (Odocoileus virginianus) were immobilized with a combination of carfentanil citrate and xylazine hydrochloride. From this study, we selected a dose of carfentanil/xylazine for the purpose of comparing immobilization parameters and physiologic effects with those of a combination of tiletamine and zolazepam (Telazol) and xylazine. Animals were initially given intramuscular injections of 10 mg xylazine and one of four doses of carfentanil (i.e., 0.5, 1.0, 1.5, and 2.0 mg). A carfentanil dose of 1.2 mg (x +/- SD = 23.5 +/- 3.2 microg/kg) and 10 mg xylazine (0.2 +/- 0.03 mg/kg) were selected, based on induction times and previously published reports, to compare with a combination of 230 mg of Telazol (4.5 +/- 0.6 mg/kg) and 120 mg xylazine (2.3 +/- 0.3 mg/kg). Time to first observable drug effects and to induction were significantly longer for deer treated with carfentanil/xylazine than with Telazol/xylazine (P < 0.01). Hyperthermia was common in deer immobilized with carfentanil/xylazine, but heart rate, respiration rate, and hemoglobin saturation were within acceptable levels. Degree of anesthesia of deer immobilized with Telazol/xylazine was superior to deer immobilized with carfentanil/xylazine. The combination of 120 mg of naltrexone hydrochloride and 6.5 mg of yohimbine hydrochloride provided rapid and complete reversal (1.9 +/- 1.1 min) of carfentanil/xylazine immobilization. Animals immobilized with Telazol/xylazine had long recovery times with occasional resedation after antagonism with 6.5 mg of yohimbine. The combination of carfentanil and xylazine at the doses tested did not provide reliable induction or immobilization of white-tailel (leer even though drug reversal was rapid and safe using naltrexone and yohimbine.