Douglas L. Armstrong

YOHIMBINE HYDROCHLORIDE REVERSAL OF KETAMINE HYDROCHLORIDE AND XYLAZINE HYDROCHLORIDE IMMOBILIZATION OF BENGAL TIGERS AND EFFECTS ON HEMATOLOGY AND SERUM CHEMISTRIES

Six bengal tigers (Panthera tigris tigris) were immobilized five times at 2-wk intervals with ketamine hydrochloride (ketamine) and xylazine hydrochloride (xylazine) mixtures at different dose levels. Hematology and serum chemistry analyses on blood samples collected at each immobilization remained normal during the study. There were acute changes in hematocrit, chloride, potassium, glucose, and bilirubin as a function of xylazine dose level. The effect of yohimbine hydrochloride (yohimbine) on the depth and duration of immobilization was evaluated in a crossover design with every animal serving as its own control at each dose. Administration of yohimbine resulted in recovery of the animals within 4–8 min in contrast to >60 min with no yohimbine treatment. There were no adverse effects noted with the yohimbine treatment and the tigers did not exhibit a relapse over the next 24 hr. Yohimbine at a dose of 5–15 mg per adult tiger provided effective reversal of 50–150 mg of xylazine per tiger.

XYLAZINE–MIDAZOLAM–KETAMINE VERSUS MEDETOMIDINE– MIDAZOLAM–KETAMINE ANESTHESIA IN CAPTIVE SIBERIAN TIGERS (PANTHERA TIGRIS ALTAICA)

Abstract Two α2-adrenoceptor agents, xylazine and medetomidine, in combination with midazolam and ketamine safely and effectively immobilized Siberian tigers (Panthera tigris altaica). The medetomidine protocol used smaller drug volumes, and induction and recovery times were shorter. Although cardiopulmonary abnormalities were noted, none were likely to be life threatening.

An Outbreak of Avian Mycobacteriosis Caused by Mycobacterium intracellulare in Little Blue Penguins (Eudyptula minor)

Abstract Mycobacterium intracellulare (MIT) was diagnosed postmortem by culture and supporting histopathology in seven birds from a flock of little blue penguins (Eudyptula minor) at the Henry Doorly Zoo (HDZ). These birds represented 20% of the deaths in the population over a 4 yr period. Clinical signs in affected birds included severe respiratory distress characterized by open-mouth breathing with chronic debilitation. On exam, plaques were noted in the larynx, trachea, and soft tissue of the caudal oropharynx. Index cases were identified on necropsy in two birds on loan to another institution in 2003. Following a case confirmed antemortem at the HDZ, a three-drug protocol of rifampin (15 mg/kg p.o. s.i.d.), ethambutol (15 mg/kg p.o. s.i.d.), and clarithromycin (10 mg/kg p.o. s.i.d.) was started on this bird in 2004 and extended to the entire flock in 2005. Gastric wash, fecal samples, and throat plaques were obtained antemortem on five birds within the flock, selected because of the presence of oral plaques, and tested by culture followed by a polymerase chain reaction assay. MIT was detected in gastric washes from four birds and in throat plaques from all five. Three more birds died during treatment. After the seventh bird died, antimicrobial susceptibility testing performed in July 2007 indicated that the MIT was now resistant to most antibiotics tested, including rifampin and ethambutol. The treatment regimen was changed to minocycline (10 mg/kg p.o. b.i.d.) and clarithromycin (10 mg/kg p.o. s.i.d.). Oral plaques were not seen on monthly rechecks of the flock through November 2008. The proposed mechanism of transmission is exposure to wild birds but the source has not been determined. These cases of avian mycobacteriosis caused by MIT are the first known cases reported in little blue penguins.

Effect of anticoagulant and venipuncture site on hematology and serum chemistries of the spiny softshell turtle (Apalone spinifera).

ABSTRACT The effect of anticoagulant and venipuncture site on hematology and serum chemistries was evaluated in eight captive spiny softshell turtles (Apalone spinifera). Animals were randomly and evenly distributed into two groups. On day 0, blood samples were collected from the dorsal coccygeal vein in turtles from group 1 and from the subcarapacial vein in turtles from group 2. On day 15, the same procedure was repeated, but turtles from group 1 were sampled from the subcarapacial vein and turtles from group 2 from the dorsal coccygeal vein. Hematologic samples were placed in ethylenediaminetetraacetic acid (EDTA) on day 0 and in heparin on day 15. Samples for chemistries were placed in serum separator tubes. All samples in EDTA were hemolyzed. Nonparametric tests were used to assess significant differences in hematologic and biochemical parameters between the two venipuncture sites. Among the biochemical parameters, statistically significant differences were only present for glucose and potassium, with the median values being higher in samples obtained from the subcarapacial vein. Correlation tests did not show any significant correlation between the values obtained from the two venipuncture sites for any of the biochemical parameters evaluated. There was also a general lack of agreement for values obtained from different venipuncture sites. This study concluded that EDTA is not an appropriate anticoagulant for this species, and serum chemistry values from paired samples taken using different venipuncture sites did not have a significant correlation or agreement.

DERMATITIS IN CAPTIVE WYOMING TOADS (BUFO BAXTERI) ASSOCIATED WITH FUSARIUM SPP.

From May 2007 to June 2008, 30 of 49 Wyoming toads (Bufo baxteri) kept at Omahas Henry Doorly Zoo (Nebraska, USA) died showing clinical signs of ventral erythema, inappetance, lethargy, and delayed righting reflex. Treatment with antifungals and antibiotics was unsuccessful in all cases. Histopathologic analyses revealed dermatitis as the primary problem in 20 of 21 toads in which skin was examined. Fungal dermatitis was present in 17 toads, with hyphae approximately 1–3 μm in diameter, and parallel cell walls and frequent septations. In 14 animals, the fungal dermatitis was the main pathologic lesion. Several species of bacteria were associated with all cases. A few animals tested positive for Ranavirus using polymerase chain reaction. Fusarium sp. was consistently cultured from skin, feces, kidneys, and from powdered food provided to crickets. Four isolates were identified as Fusarium proliferatum, Fusarium oxysporum, Fusarium solani, and Fusarium verticillioides, which suggested a secondary role of fungi. A specific underlying cause of disease could not be found, although the roles of humidity and Ranavirus infection are discussed, along with the well-known susceptibility of bufonids to fungal dermatitis.

PHARMACOKINETICS OF FLORFENICOL AFTER A SINGLE INTRAMUSCULAR DOSE IN WHITE-SPOTTED BAMBOO SHARKS (CHILOSCYLLIUM PLAGIOSUM)

Abstract This study evaluated the pharmacokinetics of florfenicol in the white-spotted bamboo shark (Chiloscyllium plagiosum). In addition to the pharmacokinetics, the potential application for treatment of bacterial meningitis was explored. A pilot study was used to compare doses of 30, 40, and 50 mg/kg i.m. Following that study, 10 adult sharks were administered a single i.m. dose of florfenicol at 40 mg/kg. Plasma and cerebrospinal fluid were collected and analyzed for florfenicol by a sensitive and specific high-pressure liquid chromatographic method. Pharmacokinetic analysis was performed using both non-compartmental and compartmental techniques. The absorption produced an average peak at 54 (±19) hr from the i.m. site of administration, and the half-life was prolonged, averaging 269.79 hr (±135.87). Florfenicol plasma concentrations peaked at an average of 11.85 μg/ml (±1.45) and were maintained above our target minimum inhibitory concentration of 4–8 μg/ml for at least 120 hr. Cerebrospinal fluid concentrations peaked at an estimated 9 μg/ml around 48 hr, surpassing the target minimum inhibitory concentration for at least 72 hr.

Comparison of Carfentanil-Xylazine and Thiafentanil- Medetomidine in Electroejaculation of Captive Gaur (Bos gaurus)

Abstract:  Carfentanil citrate and thiafentanil oxalate have been used successfully to immobilize captive and free-ranging ungulates. The objective of this study was to compare the efficacy and certain physiologic parameters of protocols by using the 2 opioids in gaur (Bos gaurus). Eight adult gaur bulls were immobilized for electroejaculation at Omahas Henry Doorly Zoo (Omaha, Nebraska, USA). All the animals were immobilized twice, by using each of the following protocols one time: 10 mg carfentanil combined with 100 mg xylazine (CX), reversed with 1,000 mg naltrexone and 24 mg yohimbine; and 12 mg thiafentanil combined with 20 mg medetomidine (TM), reversed with 120 mg naltrexone and 100 mg atipamezole. Immobilization drugs were delivered intramuscularly into the shoulder area via pole syringe. Electroejaculation was carried out by a standardized protocol to duplicate procedural stimulation on each animal. Induction and recovery times, initial rectal temperature, heart rate, respiratory rate, anesthetic depth, oxygen saturation, indirect blood pressure, and arterial blood gases were recorded at the time of initial handling, before ejaculation, and after ejaculation. Antagonists were administered 1/4 i.v. and 3/4 s.q. Both protocols require a small volume of drug for a large ungulate, provide smooth induction, and adequate anesthesia. Both protocols produced a significant hypoxemia, although the animals on CX showed slightly better blood gas values (based on lower partial pressure of carbon dioxide) and numerically lower blood pressure values. Animals on TM had better muscle relaxation and smoother recoveries, with no renarcotization noted. The results of the present study indicate the TM and CX protocols used for immobilizing gaur result in similar quality ejaculates that can be used for fertility examination as well as for assisted reproduction such as artificial insemination. Additional immobilizations need to take place to further compare these 2 combinations in this species.

EVALUATING ECHOCARDIOGRAM AND INDIRECT BLOOD PRESSURE RESULTS IN MALE WESTERN LOWLAND GORILLAS (GORILLA GORILLA GORILLA) DURING THREE PHASES OF AN ANESTHETIC PROTOCOL

Until the majority of the great ape population is trained for conscious cardiac evaluations, most individuals will require general anesthesia to perform echocardiograms. Within the veterinary community, concern exists that certain anesthetic protocols may exacerbate or artificially induce signs of cardiac disease. Because of potential cardiovascular effects, medetomidine has generally been used cautiously in patients with cardiac disease. The combination of ketamine and medetomidine is frequently used by many institutions because of its reversibility. To date, no published studies have obtained physiologic or echocardiographic parameters comparing different anesthetic protocols. In this study, with the use of seven adult male gorillas (Gorilla gorilla gorilla) with and without cardiac disease, echocardiographic and indirect blood pressure data during three phases of an anesthetic protocol were collected. The initial echocardiographic study was completed with ketamine/ medetomidine alone (5-7 mg/kg, i.m., and 0.05-0.07 mg/kg, i.m., respectively); the second study was completed after the addition of sevoflurane inhalant anesthesia to this procedure; and the third study was completed after reversal of medetomidine by administration of atipamezole (5:1 with the medetomidine dose given at induction). Without exception, ejection fractions were 15-25% lower under anesthesia with medetomidine as compared to ejection fractions after administration of atipamezole. Indirect blood pressures were higher on ketamine/ medetomidine, lower with addition of sevoflurane, and considerably lower after administration of atipamezole.

Comparative cat studies: Are tigers auditory specialists?

Although representatives of the 41 extant cat species inhabit nearly every biome on the planet and may have faced a highly diverse set of selection pressures during their evolution, relatively little effort has been made to compare commonly measured features of peripheral auditory function among species representing the family. Given their extensive geographic range, it is reasonable to suggest that auditory system adaptations may have occurred, leading to functional specialization in a subset of species. In that light, frequency‐threshold curves and response latency‐level and latency‐frequency relationships will be compared in cats of widely varying body mass inhabiting a variety of habitats. The body mass of felids spans a range of more than two orders of magnitude, with small cats like the desert sandcat, Felis margarita, weighing as little as 2 kg and the Amur tiger, Panthera tigris altaica, weighing as much as 300 kg. While most cats studied thus far appear to satisfy the conditions necessary to be labeled auditory generalists, the tiger, and perhaps members of the Panthera genus generally, may be exceptions. We will consider the possibility that big cats are auditory generalists with regard to acoustic sensitivity, but exhibit a peripheral specialization affecting low‐frequency neural latencies. [Funding provided by NSF Grant No. 0823417].

The acoustic features of the long distance advertisement call produced by Panthera tigris altaica, the Amur (Siberian) tiger.

The long distance advertisement call (LDAC) frequently referred to as a moan, an intense mew or a territorial roar, is commonly exchanged by adult members of Panthera tigris living both in captivity and in the wild. While the functionality of the call is not understood ethologically, its social nature is unambiguous, and isolated individuals living in captivity exchange the call repeatedly over extended periods of time. In this report, we concentrate on LDACs produced by P. tigris altaica. The average duration of the LDAC was just under 2 s. The average fundamental frequency, f0, was 0.155 kHz, ranging from ∼0.113 to 0.176 kHz. Spectrograms were dominated by distinct harmonically related frequency modulated frequency sweeps, although subharmonics were also observed. Overall peak frequency, the frequency exhibiting maximum acoustic power, was centered at ∼0.330 kHz and instantaneous peak frequency frequently shifted from one harmonic to another throughout the call’s time course. The bulk of broadcast energ...