Rodney Schnellbacher

Diagnosis of presumed acute ischemic stroke and associated seizure management in a Congo African grey parrot

CASE DESCRIPTION A 14-year-old Congo African grey parrot (Psittacus erithacus erithacus) was evaluated for an acute onset of falling off of its perch and tonic-clonic movements. CLINICAL FINDINGS Clinical signs were consistent with partial seizures. Findings on whole-body radiography, CBC, and plasma biochemical analysis were unremarkable. Plasma magnesium, ionized calcium, and bile acids concentrations were within reference limits. A magnetic resonance imaging (MRI) examination of the head revealed the presence of a focal hyperintensity at the central to left side of the optic chiasm and a hyperintense focus in the right side of the midbrain area in T2-weighted and FLAIR pulse sequence images. These findings were most consistent with an acute ischemic stroke with 2 brain infarcts. TREATMENT AND OUTCOME Seizures were initially managed with potassium bromide and phenobarbital administration. On the basis of poor results and difficulties to reach therapeutic blood concentrations, the treatment plan was changed to levetiracetam and zonisamide administration. Blood concentrations were monitored for both drugs, and the frequency of seizures substantially decreased thereafter. A follow-up MRI examination 2 months later revealed resolution of the hyperintense signals. During the 20-month follow-up period, subsequent clusters of seizures were managed by adjusting levetiracetam and zonisamide dosages and adding clonazepam and gabapentin administration to the treatment plan. Regression of intraparenchymal hyperintense lesions and improvement of clinical signs made a diagnosis of acute ischemic stroke most likely. CLINICAL RELEVANCE Findings for this Congo African grey parrot indicated that an antemortem diagnosis of an acute ischemic stroke followed by long-term seizure management may be possible in affected psittacines.

Intermittent Claudication-like Syndrome Secondary to Atherosclerosis in a Yellow-naped Amazon Parrot (Amazona ochrocephala auropalliata)

Abstract A 25-year-old yellow-naped Amazon parrot (Amazona ochrocephala auropalliata) was presented for nasal discharge and sneezing. Physical examination revealed poor feather quality, a mild serous nasal discharge, and a mass on the dorsal surface of the oral cavity. Cytologic examination of a mass aspirate as well as results of a choanal culture revealed squamous metaplasia of the salivary glands and bacterial rhinitis, respectively. Following resolution of the presenting conditions, the patient was presented for hind limb weakness and ataxia. The clinical signs were transient and generally resolved with rest but could be reproduced after stressful episodes, such as restraint for procedures or treatment. Test results from a complete blood count, biochemistry profile, whole-body radiographs, needle electromyography of the leg muscles, and an edrophonium challenge test were within reference limits. Based on the clinical signs and results of the diagnostic workup, the presumptive diagnosis was intermittent claudication, a condition caused by peripheral vascular disease and defined as intermittent weakness and pain in the legs induced by exercise and relieved by rest. Shortly after initiation of treatment with isoxsuprine, the bird died. Postmortem examination and histopathology revealed severe atherosclerotic lesions throughout the vascular system with stenotic lesions present in the abdominal aorta and femoral arteries. Electron microscopic examination of the great arteries was also performed and helped to further characterize the nature of the lesions. This case is the first report, to our knowledge, of an intermittent claudication-like syndrome associated with peripheral atherosclerosis in a psittacine bird. In addition, the distribution and some of the macroscopic and histopathologic features of the lesions differ from previous descriptions of atherosclerosis in psittacine birds.

Palpation- and ultrasound-guided brachial plexus blockade in Hispaniolan Amazon parrots (Amazona ventralis)

OBJECTIVE To compare palpation-guided with ultrasound-guided brachial plexus blockade in Hispaniolan Amazon parrots. STUDY DESIGN Prospective randomized experimental trial. ANIMALS Eighteen adult Hispaniolan Amazon parrots (Amazona ventralis) weighing 252-295 g. METHODS After induction of anesthesia with isoflurane, parrots received an injection of lidocaine (2 mg kg(-1)) in a total volume of 0.3 mL at the axillary region. The birds were randomly assigned to equal groups using either palpation or ultrasound as a guide for the brachial plexus block. Nerve evoked muscle potentials (NEMP) were used to monitor effectiveness of brachial plexus block. The palpation-guided group received the local anesthetic at the space between the pectoral muscle, triceps, and supracoracoideus aticimus muscle, at the insertion of the tendons of the caudal coracobrachial muscle, and the caudal scapulohumeral muscle. For the ultrasound-guided group, the brachial plexus and the adjacent vessels were located with B-mode ultrasonography using a 7-15 MHz linear probe. After location, an 8-5 MHz convex transducer was used to guide injections. General anesthesia was discontinued 20 minutes after lidocaine injection and the birds recovered in a padded cage. RESULTS Both techniques decreased the amplitude of NEMP. Statistically significant differences in NEMP amplitudes, were observed within the ultrasound-guided group at 5, 10, 15, and 20 minutes after injection and within the palpation-guided group at 10, 15, and 20 minutes after injection. There was no statistically significant difference between the two groups. No effect on motor function, muscle relaxation or wing droop was observed after brachial plexus block. CONCLUSIONS AND CLINICAL RELEVANCE The onset of the brachial plexus block tended to be faster when ultrasonography was used. Brachial plexus injection can be performed in Hispaniolan Amazon parrots and nerve evoked muscle potentials were useful to monitor the effects on nerve conduction in this avian species. Neither technique produced an effective block at the doses of lidocaine used and further study is necessary to develop a useful block for surgical analgesia.

Effects of dopamine and dobutamine on isoflurane-induced hypotension in Hispaniolan Amazon parrots (Amazona ventralis).

OBJECTIVE To assess the effects of dopamine and dobutamine on the blood pressure of isoflurane-anesthetized Hispaniolan Amazon parrots (Amazona ventralis). ANIMALS 8 Hispaniolan Amazon parrots. PROCEDURES A randomized crossover study was conducted. Each bird was anesthetized (anesthesia maintained by administration of 2.5% isoflurane in oxygen) and received 3 doses of each drug during a treatment period of 20 min/dose. Treatments were constant rate infusions (CRIs) of dobutamine (5, 10, and 15 μg/kg/min) and dopamine (5, 7, and 10 μg/kg/min). Direct systolic, diastolic, and mean arterial pressure measurements, heart rate, esophageal temperature, and end-tidal partial pressure of CO(2) were recorded throughout the treatment periods. RESULTS Mean ± SD of the systolic, mean, and diastolic arterial blood pressures at time 0 (initiation of a CRI) were 132.9 ± 22.1 mm Hg, 116.9 ± 20.5 mm Hg, and 101.9 ± 22.0 mm Hg, respectively. Dopamine resulted in significantly higher values than did dobutamine for the measured variables, except for end-tidal partial pressure of CO(2). Post hoc multiple comparisons revealed that the changes in arterial blood pressure were significantly different 4 to 7 minutes after initiation of a CRI. Overall, dopamine at rates of 7 and 10 μg/kg/min and dobutamine at a rate of 15 μg/kg/min caused the greatest increases in arterial blood pressure. CONCLUSIONS AND CLINICAL RELEVANCE Dobutamine CRI at 5, 10, and 15 μg/kg/min and dopamine CRI at 5, 7, and 10 μg/kg/min may be useful in correcting severe hypotension in Hispaniolan Amazon parrots caused by anesthesia maintained with 2.5% isoflurane.

Estimation of intrathoracic arterial diameter by means of computed tomographic angiography in Hispaniolan Amazon parrots

OBJECTIVE To establish a computed tomography (CT)-angiography protocol and measure the diameters of major arteries in parrots. ANIMALS 13 Hispaniolan Amazon parrots (Amazona ventralis). PROCEDURES 16-slice CT scanning was used to measure the apparent diameter of the ascending aorta, abdominal aorta, pulmonary arteries, and brachiocephalic trunk. Before scanning, all birds underwent ECG and echocardiographic assessment and were considered free of detectable cardiovascular diseases. Each bird was anesthetized, and a precontrast helical CT scan was performed. Peak aortic enhancement was established with a test bolus technique via dynamic axial CT scan over a predetermined single slice. An additional bolus of contrast medium was then injected, and a helical CT-angiography scan was performed immediately afterward. Arterial diameter measurements were obtained by 2 observers via various windows before and after injection, and intra- and interobserver agreement was assessed. RESULTS Reference limits were determined for arterial diameter measurements before and after contrast medium administration in pulmonary, mediastinal, and manual angiography windows. Ratios of vertebral body diameter to keel length were also calculated. Intraobserver agreement was high (concordance correlation coefficients ≥ 0.95); interobserver agreement was medium to high (intraclass correlation coefficients ≥ 0.65). CONCLUSIONS AND CLINICAL RELEVANCE CT-angiography was safe and is of potential diagnostic value in parrots. We recommend performing the angiography immediately after IV injection of 3 mL of iohexol/kg. Arterial diameter measurements at the described locations were reliable.

Malignant B-cell lymphoma with Mott cell differentiation in a ferret (Mustela putorius furo).

A 3.5-year-old, male, neutered ferret (Mustela putorius furo) was presented with a 3-day history of lethargy and anorexia. Splenic aspirates revealed high numbers of intermediate-sized lymphocytes and Mott cells interpreted as lymphoma with Mott cells. The ferret was euthanized because of a poor clinical prognosis. Postmortem examination revealed markedly enlarged spleen and lymph nodes, with multifocal white nodules in the liver parenchyma. Histologically, the spleen had multifocal large nodules composed of neoplastic lymphocytes with frequent Mott cells. Similar neoplastic cells were present in the sections of liver, lymph nodes, and bone marrow. These cells were cluster of differentiation (CD)3-negative, CD79α-positive, and lambda light-chain—positive. Electron microscopy revealed that the cytoplasm of the neoplastic Mott cells had increased, disorganized, dilated, rough endoplasmic reticulum containing electron-dense immunoglobulin. On the basis of cytologic, histopathologic, immunohistochemical, and electron microscopic findings, a malignant B-cell lymphoma with Mott cell differentiation was diagnosed.

Effects of lidocaine administration via continuous rate infusion on the minimum alveolar concentration of isoflurane in New Zealand White rabbits (Oryctolagus cuniculus)

OBJECTIVE To evaluate the effect of a continuous rate infusion (CRI) of lidocaine on the minimum alveolar concentration (MAC) of isoflurane in rabbits. ANIMALS Five 12-month-old female New Zealand White rabbits (Oryctolagus cuniculus). PROCEDURES Rabbits were anesthetized with isoflurane. Baseline isoflurane MAC was determined by use of the tail clamp technique. A loading dose of lidocaine (2.0 mg/kg, IV) was administered followed by a CRI of lidocaine at 50 μg/kg/min. After 30 minutes, isoflurane MAC was determined. Another loading dose was administered, and the lidocaine CRI then was increased to 100 μg/kg/min. After 30 minutes, isoflurane MAC was determined again. Plasma samples were obtained for lidocaine analysis after each MAC determination. RESULTS Baseline isoflurane MAC was 2.09%, which was similar to previously reported values in this species. Lidocaine CRI at 50 and 100 μg/kg/min induced significant reductions in MAC. The 50 μg/kg/min CRI resulted in a mean plasma lidocaine concentration of 0.654 μg/mL and reduction of MAC by 10.5%. The 100 μg/kg/min CRI of lidocaine resulted in a mean plasma concentration of 1.578 μg/mL and reduction of MAC by 21.7%. Lidocaine also induced significant decreases in arterial blood pressure and heart rate. All cardiopulmonary variables were within reference ranges for rabbits anesthetized with inhalation anesthetics. No adverse effects were detected; all rabbits had an uncomplicated recovery from anesthesia. CONCLUSIONS AND CLINICAL RELEVANCE Lidocaine administered as a CRI at 50 and 100 μg/kg/min decreased isoflurane MAC in rabbits. The IV administration of lidocaine may be a useful adjunct in anesthesia of rabbits.

Emergency Presentations Associated with Cardiovascular Disease in Exotic Herbivores

Abstract Exotic animals, including small herbivores, are increasing in popularity as companion animals. Commonly owned exotic herbivores include guinea pigs, chinchillas, and rabbits. These animals fall into the category of prey species with an inherent instinct to hide their illness until severely affected by the disease process. Therefore, any of these animals presented as an emergency case must be carefully evaluated for chronic underlying illness. Cardiovascular emergency and critical care principles are similar across all mammalian species. However, specialized techniques and adaptations are occasionally required because of the unique physiology and natural behaviors of these animals. It is essential to evaluate and stabilize these patients before attempting definitive diagnostic plans. Emergency cardiovascular presentations, as in other mammals, consist of congestive heart failure, arrhythmias, pericardial effusion, and toxicities that can result in cardiac and pulmonary arrest. Cardiac disease is a relatively common finding in small exotic mammals, but there are few peer-reviewed reports regarding diagnosis and treatment of heart disease in these species. Diagnostic testing and treatment options are generally based on knowledge of small animal medicine.

The Efficacy of Intranasal Administration of Dexmedetomidine and Ketamine to Yellow-Bellied Sliders (Trachemys scripta scripta)

Abstract The purpose of this study was to evaluate the efficacy of dexmedetomidine and ketamine and reversal with atipamezole administered intranasally to Trachemys scripta scripta. Eight healthy adult turtles received 0.2 and 10 mg/kg of dexmedetomidine and ketamine, respectively. Heart rate, respiratory rate, temperature, and sedation (on a scale of 0–4) were measured. Blood was collected 45 min post induction for drug plasma levels from both the subcarapacial and tail veins, followed by intranasal atipamezole administration (0.5 mg/kg). The most frequent sedation scores (2 and 3) provided a level of sedation deep enough to perform a thorough physical exam and minor clinical procedures. All of the turtles became active in 18.9 ± 7 min after atipamezole administration. No adverse effects were observed and all measured cardiopulmonary parameters were within normal limits. Plasma levels of both dexmedetomidine and ketamine indicated adequate absorption and distribution with no difference in the levels obtained from either the subcarapacial or the tail venipuncture sites. A combination of dexmedetomidine–ketamine can be used intranasally to induce moderate to heavy sedation for physical examination, venipuncture, and other minor procedures in the yellow-bellied slider without adverse effects. In addition, the intranasal administration of atipamezole appears efficacious for reversal of dexmedetomidine. Intranasal administration of anesthetic agents holds promise for sedating and anesthetizing chelonians, which are often difficult to thoroughly examine and restrain for biological sample collection, both in the clinic and in the field.

Ameloblastoma in a wild black rat snake (Pantherophis alleghaniensis)

Reports of neoplasia in captive reptiles are becoming more frequent; however, there is still scarce knowledge of the occurrence of neoplasia in wild reptiles. A wild black rat snake (Pantherophis alleghaniensis) was presented to the Zoological Medicine service of the University of Georgia’s Veterinary Teaching Hospital with a 3 cm in diameter solid mandibular mass that was partially ulcerated. Radiographically, the mass was radiopaque with small bone spicules and partial osteolysis of the adjacent mandible. Histologic examination of the mass revealed a neoplasm composed of cuboidal to polygonal cells arranged in islands, anastomosing cords, and trabeculae of pseudostratified epithelium with a palisading peripheral layer of densely packed columnar cells with cytoplasmic clearing. The neoplastic tissue was separated from the mesenchyme by a prominent band of fine collagen. Neoplastic cells were positive for cytokeratin and negative for smooth muscle actin. Electron microscopy highlighted the presence of tonofilaments and microvilli. These findings led to the diagnosis of ameloblastoma, an odontogenic epithelial tumor known to occur in humans and most veterinary species.