Andrew C. Cushing

USE OF THIAFENTANIL-MEDETOMIDINE FOR THE INDUCTION OF ANESTHESIA IN EMUS (DROMAIUS NOVAEHOLLANDIAE) WITHIN A WILD ANIMAL PARK

Abstract Fifteen adult emu (Dromaius novaehollandiae) anesthetic events were successfully undertaken with the use of thiafentanil oxalate (A3080) 0.175 mg/kg i.m. (SD 0.026) and medetomidine 0.092 mg/kg i.m. (SD 0.009) via remote injection. Following induction, the birds were transported to the clinic, where a venous blood gas sample was taken for analysis, which indicated a respiratory acidosis, with a mean arterial pCO2 of 54.46 mmHg (SD 9.31) and venous pH of 7.135 (SD 0.11), most likely due to moderate bradypnoea. Atipamezole 0.2 mg/kg i.v. (SD 0.02) was administered, immediately followed by orotracheal intubation initiating 2–3% isoflurane with 2 L/min oxygen flow. Parameters evaluated during anesthesia included heart rate, respiratory rate, anesthetic depth, and electrocardiogram readings. Physical exams plus any required procedures were performed in addition to venous blood samples for biochemistry and full blood counts. The birds were then recovered in a crate padded with grass hay with administration of 8.75 mg/kg (SD 1.36) naltrexone (50 mg/mg A3080) administered in equal doses i.v. and i.m. along with 5 mg midazolam i.m. to reduce excitement. Emus were placed in a lateral position and given 4 L/min oxygen via the endotracheal tube, until movement of the head and neck necessitated extubation. Recovery was rapid and smooth in each case with a mean time of 3.1 min from antagonist administration to sternal recovery. On the basis of rapid, smooth, and successful inductions and recoveries, the described dosage of thiafentanil and medetomidine, with administration of midazolam prior to recovery, is recommended for immobilization of adult emus. Due to evidence of respiratory acidosis and bradypnoea, careful monitoring should be instituted throughout and oxygen provision recommended from initial contact.

THIAFENTANIL-DEXMEDETOMIDINE-TELAZOL ANESTHESIA IN GREATER RHEAS (RHEA AMERICANA)

Ratite anesthetic events are often dangerous because these birds use their powerful legs and clawed feet as a defense, and physical restraint can result in self-trauma or injury to handlers. Although various combinations of opioids, alpha-2 adrenergic agonists, and dissociative agents have been employed in ratites, few effective chemical immobilization protocols have been documented for rheas (Rhea spp.). An intramuscular, remote-delivered combination of thiafentanil (0.30 +/- 0.08 mg/kg), dexmedetomidine (7.31 +/- 2.72 microg/kg), and tiletamine-zolazepam (5.09 +/- 2.31 mg/kg) was utilized in eight adult (four male, four female) greater rheas (Rhea americana). Smooth inductions were observed. During clinical procedures, birds were intubated and maintained on isoflurane gas, and atipamezole was administered to antagonize the dexmedetomidine. At recovery, naltrexone was administered to antagonize the thiafentanil, and midazolam was administered to smooth crate recoveries until release. This low-volume, high-potency, reversible drug combination demonstrated safe inductions and smooth recoveries and proved to be a reliable anesthetic regimen for greater rheas.

SEROLOGIC RESPONSE TO CANINE DISTEMPER VACCINATION IN CAPTIVE LINNAEUS'S TWO-TOED SLOTHS (CHOLOEPUS DIDACTYLUS) AFTER A FATAL CANINE DISTEMPER VIRUS OUTBREAK

Abstract Canine distemper virus (CDV) affects many wild and captive, nondomestic species worldwide but has not been previously reported in Xenarthra. Paucity of information on vaccination safety and efficacy presents challenges for disease prevention in captive collections. CDV infections and subsequent mortalities in five captive Linnaeuss two-toed sloths (Choloepus didactylus) in eastern Tennessee are reported. Clinical signs included oculonasal discharge, oral ulcerations, and diarrhea, and the diagnosis was confirmed by necropsy, histopathology, immunohistochemistry, virus isolation, and polymerase chain reaction. Viral sequencing identified the strain to be consistent with a new CDV lineage currently affecting domestic dogs and wildlife in Tennessee. Seven sloths were examined and vaccinated using a recombinant CDV vaccine on days 0 and 21. Subsequent blood samples showed increased titers in 3/4 sloths. Based on the outbreak and serologic findings postvaccination without adverse effects, the authors recommend recombinant CDV vaccination in sloths exposed to known carriers of CDV.

INTRAUTERINE FETAL DEATH WITH SUBSEQUENT QUILL EXFOLIATION AND DISSEMINATION IN A NORTH AMERICAN PORCUPINE (ERETHIZON DORSATUM)

An adult female, wild North American porcupine (Erethizon dorsatum) presented with bilateral cataracts and naso-ocular discharge. A pregnancy was identified by radiography with a near-full-term fetus, which was delivered stillborn 4 wk later with hard, developed quills. At that time, a repeated examination and further imaging, including computed tomography, demonstrated a uterine mass that was identified as a choriocarcinoma following ovariohysterectomy. Additionally, numerous exfoliated quills were discovered throughout the abdomen, most of which were removed during the surgical procedure. Ultimately, development of peritonitis despite medical care led to the porcupines death. Necropsy confirmed a wide migration of the quills with extensive serosal adhesions and granulomas affecting liver, lungs, urinary bladder, kidneys, and gastrointestinal tract.

Metastatic pancreatic carcinoma and bronchioloalveolar adenomas in an Egyptian fruit bat (Rousettus aegyptiacus).

An adult female, intact Egyptian fruit bat (Rousettus aegyptiacus) was presented for lethargy, anorexia, and markedly reduced flying activity. Physical and ultrasound examinations were suggestive of an abdominal mass with free fluid within the abdomen. Based on the poor and deteriorating clinical condition of the animal, euthanasia was elected. Gross necropsy revealed an irregular thickening at the root of the mesentery and a diffusely, dark-red liver with rounded hepatic margins. Histologic examination revealed extensive neoplastic effacement of the pancreas with invasion into the surrounding mesentery and mesenteric lymph nodes and metastatic spread to the liver. Based on the morphology of the neoplastic cells, the involvement of the pancreas, and immunohistochemistry, a diagnosis of metastatic pancreatic carcinoma was made. Additionally, two small neoplasms were identified in the lungs. These masses were distinct from the carcinoma, and their morphology was consistent with bronchioloalveolar adenomas. This is the first known report of either benign pulmonary lesions or pancreatic carcinomas in the order Chiroptera.

Anesthesia of Tibetan yak (Bos grunniens) using thiafentanil - xylazine and carfentanil - xylazine.

Abstract:  The use of 0.025 ± 0.012 mg/kg (median ± interquartile range) thiafentanil with 0.15 ± 0.03 mg/kg xylazine (TX) and 0.011 ± 0.0015 mg/kg carfentanil with 0.25 ± 0.093 mg/kg xylazine (CX), with dosages based on estimated bodyweight, was used in the anesthesia of 37 Tibetan yak (Bos grunniens) housed within a drive-through animal park setting. The median time to lateral recumbency was 5 and 7 min for each group, respectively. With the addition of propofol in 8 CX animals and 17 TX animals, the anesthetic plane was suitable for a wide range of procedures. The median time to standing recovery following administration of naltrexone was 4 ± 3.5 min with TX and 7 ± 1.5 min with CX. There was one fatality and one case of renarcotization in the TX group. Overall, the dosages used in the study provided a reliable and useful anesthetic induction protocol, with TX animals demonstrating a more rapid induction and recovery with less cardiac depression than CX animals.

The electrocardiogram of anesthetized captive adult emus (Dromaius novaehollandiae)

OBJECTIVE To characterize the electrocardiogram (ECG) of anesthetized adult emus (Dromaius novaehollandiae). ANIMALS Ten clinically healthy adult emus anesthetised for routine physical examination and an electrocardiogram, for both monitoring and investigation into any evidence of cardiac disease. METHODS The ECGs for each emu were obtained in right lateral recumbency, using a modified electrode placement that replicated the standard bipolar leads used in small mammals. Lead II was used for waveform analysis. RESULTS Median P wave amplitude was 0.55 mV (range: 0.2-0.92 mV) and P wave duration was 0.06 s (0.04-0.09 s). S wave amplitude measured 1.42 mV (0.92-2.12 mV), T wave amplitude 0.67 mV (0.16-0.83 mV) and QRS duration was 0.07 s (0.07-0.12 s). Ninety percent of the QRS complexes were of rS type. CONCLUSION Our study provides electrocardiographic baseline data for anesthetized adult emus.

Bilateral Malignant Seminoma With Ventricular Metastasis in a Bald Eagle (Haliaeetus leucocephalus)

Abstract A 30-year-old bald eagle (Haliaeetus leucocephalus) was presented with a history of hyporexia and lethargy. Results of initial hematologic testing, biochemical analysis, and fecal examination were unremarkable, and clinical signs did not resolve with supportive care and management changes. Results of echocardiography, based on auscultation of a murmur, and coelomic endoscopy, based on the presence of a soft tissue opacity on radiographs, as well as an aspergillosis panel were largely unsuccessful in determining a definitive diagnosis. Euthanasia was performed after the eagle did not recover from anesthesia after endoscopy. Necropsy results demonstrated bilateral testicular seminomas with metastases to the ventriculus. This case demonstrates an abnormal metastasis of a common reproductive tumor in an avian species.

Use of plethysmographic variability index and perfusion index to evaluate changes in arterial blood pressure in anesthetized tigers (Panthera tigris)

OBJECTIVE To investigate use of the plethysmographic variability index (PVI) and perfusion index (PI) for evaluating changes in arterial blood pressure in anesthetized tigers (Panthera tigris). ANIMALS 8 adult tigers. PROCEDURES Each tiger was anesthetized once with a combination of ketamine, midazolam, medetomidine, and isoflurane. Anesthetic monitoring included assessment of PI, PVI, direct blood pressure measurements, anesthetic gas concentrations, esophageal temperature, and results of capnography and ECG. Mean arterial blood pressure (MAP) was maintained for at least 20 minutes at each of the following blood pressure conditions: hypotensive (MAP = 50 ± 5 mm Hg), normotensive (MAP = 70 ± 5 mm Hg), and hypertensive (MAP = 90 ± 5 mm Hg). Arterial blood gas analysis was performed at the beginning of anesthesia and at each blood pressure condition. RESULTS Mean ± SD PI values were 1.82 ± 2.38%, 1.17 ± 0.77%, and 1.71 ± 1.51% and mean PVI values were 16.00 ± 5.07%, 10.44 ± 3.55%, and 8.17 ± 3.49% for hypotensive, normotensive, and hypertensive conditions, respectively. The PI values did not differ significantly among blood pressure conditions. The PVI value for the hypotensive condition differed significantly from values for the normotensive and hypertensive conditions. The PVI values were significantly correlated with MAP (r = -0.657). The OR of hypotension to nonhypotension for PVI values ≥ 18% was 43.6. CONCLUSIONS AND CLINICAL RELEVANCE PVI was a clinically applicable variable determined by use of noninvasive methods in anesthetized tigers. Values of PVI ≥ 18% may indicate hypotension.

THE PASSAGE AND DURATION OF ANTIBODIES TO WEST NILE VIRUS IN HUMBOLDT PENGUINS (SPHENISCUS HUMBOLDTI)

Abstract West Nile virus (genus Flavivirus) outbreaks and mortality events have been documented in both wild and captive avian species, including penguins. Serologic response to vaccination in avian species has varied and appears to be largely species dependent; however, Humboldt penguins (Spheniscus humboldti) previously showed excellent rates of seroconversion. The goal of this study was to determine virus neutralization titers of 17 Humboldt penguin hens and their subsequent eggs, chicks, or both following vaccination with a killed West Nile vaccine. Chicks were also vaccinated at 56, 70, and 84 days old. Titers were measured from 10–346 days prior to lay as well as serially in seven chicks. Data collected showed positive rank correlation between maternal titers and yolk titers (ρ = 0.90, P < 0.0001, n = 14) but no association between booster vaccination and yolk titers. All seven chicks had detectable antibody on days 14 and 28, and antibody levels had increased (relative to day 56) in 3 of 6 chicks (50%; 95% confidence interval 14–86%) by day 112. Further information is provided on a suggested vaccination schedule for Humboldt penguin chicks based on a time-dependent decline in maternal antibody titers. Cell-mediated immunity and experimental challenge following vaccination have not yet been investigated in this species.