Subcutaneous administration of ceftazidime at 20 and 40 mg/kg produces theoretically therapeutic plasma concentrations for at least 120 hours in red-eared sliders (Trachemys scripta elegans).

OBJECTIVE: To evaluate and compare the pharmacokinetic parameters of SC ceftazidime administered at 20 and 40 mg/kg to red-eared sliders. ANIMALS: 8 adult red-eared sliders (Trachemys scripta elegans). METHODS: In a sequential, 2-period study with a 3-week washout period between treatments, ceftazidime was administered SC to turtles at 20 and 40 mg/kg. Blood samples were collected from the subcarapacial sinus at 0, 24, 48, 72, 96, and 120 hours after ceftazidime administration. Plasma ceftazidime concentrations were quantified using reversed-phase HPLC. RESULTS: Mean plasma half-life after 20- and 40-mg/kg dosing was 39.75 ± 8.0 hours and 33.03 ± 6.56 hours, respectively. Mean maximum plasma concentration after 20- and 40-mg/kg dosing was 71.0 ± 15.93 µg/mL and 120.0 ± 30.62 µg/mL, respectively. Mean plasma ceftazidime concentrations remained ≥ 8 µg/mL, the theoretical MIC for various reptile pathogens for all time points. CLINICAL RELEVANCE: Results indicate that ceftazidime dosed at either 20 or 40 mg/kg produces plasma concentrations exceeding the theoretical MIC of various reptile pathogens for at least 120 hours. An ideal dosing interval could not be determined, as all plasma concentrations remained above the threshold of interest for all time points. Follow-up studies should focus on establishing a dosing interval and more rigorous monitoring for potential adverse effects.

Highly Pathogenic Avian Influenza A(H5N1) Virus Clade 2.3.4.4b Infections in Wild Terrestrial Mammals, United States, 2022.

We describe the pathology of natural infection with highly pathogenic avian influenza A(H5N1) virus of Eurasian lineage Goose/Guangdong clade 2.3.4.4b in 67 wild terrestrial mammals throughout the United States during April 1‒July 21, 2022. Affected mammals include 50 red foxes (Vulpes vulpes), 6 striped skunks (Mephitis mephitis), 4 raccoons (Procyon lotor), 2 bobcats (Lynx rufus), 2 Virginia opossums (Didelphis virginiana), 1 coyote (Canis latrans), 1 fisher (Pekania pennanti), and 1 gray fox (Urocyon cinereoargenteus). Infected mammals showed primarily neurologic signs. Necrotizing meningoencephalitis, interstitial pneumonia, and myocardial necrosis were the most common lesions; however, species variations in lesion distribution were observed. Genotype analysis of sequences from 48 animals indicates that these cases represent spillover infections from wild birds.

Clinical, pathologic, and immunohistochemical features of pituitary tumors in 4 chinchillas.

Pituitary tumors are rare in chinchillas. This report describes the clinical, gross, histologic, and immunohistochemical characteristics of pituitary tumors in 4 chinchillas. The affected chinchillas were females between 4 and 18 years of age. Clinically, neurologic signs were most commonly reported and included depression, obtundation, seizure, head-pressing, ataxia, and possible blindness. Computed tomography scanning of 2 chinchillas revealed solitary intracranial extra-axial masses in the region of the pituitary gland. Two pituitary tumors were confined to the pars distalis; the other 2 invaded the brain. Based on their microscopic appearances and lack of distant metastases, all 4 tumors were diagnosed as pituitary adenomas. Immunohistochemically, all pituitary adenomas were weakly to strongly positive for growth hormone, most consistent with the diagnosis of somatotropic pituitary adenomas. To the authors' knowledge, this is the first detailed report of the clinical, pathologic, and immunohistochemical features of pituitary tumors in chinchillas.

Pharmacokinetics of ceftazidime in Northern leopard frogs (Lithobates pipiens) at two different doses and administration routes.

OBJECTIVE: To determine an optimal ceftazidime dosing strategy in Northern leopard frogs (Lithobates pipiens) by evaluation of 2 different doses administered SC and 1 dose administered transcutaneously. ANIMALS: 44 Northern leopard frogs (including 10 that were replaced). PROCEDURES: Ceftazidime was administered to frogs SC in a forelimb at 20 mg/kg (n = 10; SC20 group) and 40 mg/kg (10; SC40 group) or transcutaneously on the cranial dorsum at 20 mg/kg (10; TC20 group). Two frogs in each ceftazidime group were euthanized 12, 24, 48, 72, and 96 hours after drug administration. Plasma, renal, and skin concentrations of ceftazidime were measured by means of reversed-phase high-performance liquid chromatography. Four control frogs were used for assay validation. RESULTS: Mean plasma half-life of ceftazidime in the SC20, SC40, and TC20 groups was 9.01 hours, 14.49 hours, and too low to determine, respectively. Mean maximum plasma ceftazidime concentration was 92.9, 96.0, and 1.3 µg/mL, respectively. For 24 hours after drug administration in the SC20 and SC40 groups, plasma ceftazidime concentration exceeded 8 µg/mL. Renal and skin concentrations were detectable at both doses and routes of administration; however, skin concentrations were significantly lower than renal and plasma concentrations. CONCLUSIONS AND CLINICAL RELEVANCE: Findings indicated that ceftazidime administration to Northern leopard frogs at 20 mg/kg, SC, every 24 hours would achieve a plasma concentration exceeding the value considered effective against common amphibian pathogens. Transcutaneous administration of the injectable ceftazidime formulation at 20 mg/kg warrants further investigation but is not currently recommended because of a potential lack of efficacy.

NEOPLASIA IN CAPTIVE CRANES.

A retrospective study of neoplasia was conducted from necropsy and histologic reports of 446 cranes representing all 15 extant species. Cases were obtained from the International Crane Foundation (ICF), Northwest ZooPath (NWZP), and six other zoologic institutions in the United States during 1993 to 2019. Only reports from ICF (n = 61) and NWZP (n = 374) were used for estimates of disease prevalence. Overall prevalence of neoplasia was 7.35% (32 of 435), with a metastasis rate of 31.8%. Seventeen types of neoplasms were identified. Geriatric cranes were the most common age class affected (60%). The digestive system was most frequently involved (n = 12; 27.3%), followed by urinary (n = 8; 18.2%) and integumentary systems (n = 6; 13.6%). Carcinoma was the most common tumor type across all species (n = 15; 34.0%) followed by benign epithelial tumors (adenomas; n = 11; 25.0%). Multiple neoplasms were observed in only one crane. Of the cases with metastasis, hematopoietic, reproductive, and respiratory tumors had 100% metastasis (2 of 2, 2 of 2, and 3 of 3, respectively), whereas tumors of the integumentary, nervous, and musculoskeletal systems had no evidence of metastasis (0 of 7, 0 of 3, and 0 of 1, respectively). Overall, Gruidae species were found to have a high prevalence of neoplasia but a low rate of metastasis compared with other avian species with the highest species-specific rates in Eurasian (Grus grus), demoiselle (Anthropoides virgo), and wattled cranes (Bugeranus carunculatus) (40.0%, 21.4%, and 19.0%, respectively). This is the first large-scale study of neoplasia in cranes.

Determination of ceftazidime in plasma by RP-HPLC and ultraviolet detection.

A simple high-performance liquid chromatography method for the determination of ceftazidime in plasma has been developed. Using an ultrafiltration technique samples were separated by reverse-phase high-performance liquid chromatography on a Symmetry C18 4.6 × 250 mm column (5.0 µm) and ultraviolet absorbance was measured at 260 nm. The mobile phase was a mixture of 10 mm potassium phosphate monobasic pH 2.5 with phosphoric acid and acetonitrile (90:10). The standard curve ranged from 0.1 to 100 µg/ml. Intra- and inter-assay variability for ceftazidime was <12%, and the average recovery was 89%. The lower limit of quantification was 0.1 µg/ml. This method has been used successfully to analyze frog plasma samples at this institution and it could be applied to other small volume samples in a clinical or research setting.

Diagnostic evaluation of fatal Balamuthia mandrillaris meningoencephalitis in a captive Bornean orangutan (Pongo pygmaeus) with identification of potential environmental source and evidence of chronic exposure.

A female Bornean orangutan (Pongo pygmaeus) aged 11 years and 6 months was examined by veterinarians after caretakers observed lethargy and facial grimacing. Within 72 h the primate had left-sided hemiparesis that worsened over the next week. An MRI revealed a focal right-sided cerebral mass suspected to be a neoplasm. Ten days after onset of clinical signs, the orangutan died. On postmortem exam, the medial right parietal lobe was replaced by a 7 × 4 × 3.5 cm focus of neuromalacia and hemorrhage that displaced the lateral ventricle and abutted the corpus callosum. Histopathology of the cerebral lesion revealed pyogranulomatous meningoencephalitis with intralesional amoeba trophozoites and rare cysts. Fresh parietal lobe was submitted to the Centers for Disease Control and Prevention lab for multiplex free-living amoebae real-time PCR and detected Balamuthia mandrillaris DNA at a high burden. Mitochondrial DNA was sequenced, and a 760-bp locus 19443F/20251R was compared to several human infections of B. mandrillaris and shown to be identical to the isolates from four human cases of encephalitis: 1998 in Australia, 1999 in California, 2000 in New York, and 2010 in Arizona. Indirect immunofluorescent antibody testing of stored serum samples indicated exposure to B. mandrillaris for at least 2 years prior to death. Within 1 week of the orangutan's death, water from the exhibit was analyzed and identified the presence of B. mandrillaris DNA, elucidating a possible source of exposure. B. mandrillaris, first reported in a mandrill in 1986, has since occurred in humans and animals and is now considered an important emerging pathogen.

Evaluation of subcutaneous administration of alfaxalone-midazolam and ketamine-midazolam as sedation protocols in African pygmy hedgehogs (Atelerix albiventris).

OBJECTIVE: To evaluate SC administration of 2 sedation protocols, ketamine-midazolam (KM) and alfaxalone-midazolam (AM), in African pygmy hedgehogs (Atelerix albiventris). ANIMALS: 9 healthy adult hedgehogs (5 males, 4 females). PROCEDURES: A randomized, blinded, complete crossover study was performed. Sedation was induced by SC administration of either ketamine (30 mg/kg [14 mg/lb]) with midazolam (1 mg/kg [0.45 mg/lb]) or alfaxalone (3 mg/kg [1.4 mg/lb]) with midazolam (1 mg/kg), including a 2-week washout period between treatments. Flumazenil (0.05 mg/kg [0.02 mg/lb], SC) was administered 45 minutes after administration of either protocol to reverse the effects of midazolam. Physiologic variables, reflexes, and behaviors were monitored. Food intake and body weight were measured before and after sedation. RESULTS: Deep sedation characterized by complete loss of the righting reflex, decreased jaw tone, decreased pelvic limb withdrawal reflex, and preservation of the palpebral reflex was produced in 7 of 9 hedgehogs after KM administration and all 9 hedgehogs after AM administration. Mean ± SD time to loss of righting reflex was 6.4 ± 2.4 minutes after KM administration and 10 ± 4.0 minutes after AM administration. Following flumazenil administration, no significant difference was found in recovery time between sedation with KM (18.8 ± 12.7 minutes) and AM (14.4 ± 7.8 minutes). No significant differences were found in respiratory rate, oxygen saturation, or body temperature between protocols, whereas heart rate was higher for sedation with KM. Both sedation protocols resulted in a transient reduction in food intake. CONCLUSIONS AND CLINICAL RELEVANCE: Subcutaneous administration of KM and AM provided deep sedation that might be useful to facilitate routine, noninvasive procedures in hedgehogs.

Pharmacokinetics of subcutaneously administered hydromorphone in bearded dragons (Pogona vitticeps) and red-eared slider turtles (Trachemys scripta elegans).

OBJECTIVE: To determine pharmacokinetic dosing strategy in bearded dragons (Pogona vitticeps) and red-eared sliders (Trachemys scripta elegans) based on two subcutaneously (SC) administered doses of hydromorphone (0.5 and 1.0 mg kg-1). STUDY DESIGN: Randomized crossover study. ANIMALS: Six healthy adult bearded dragons, seven healthy adult red-eared slider turtles. METHODS: Hydromorphone (0.5 and 1.0 mg kg-1; 2 mg mL-1) was administered SC dorsolateral to the scapulae in the bearded dragons and between the head and thoracic limb of the red-eared slider turtles. Blood was collected for hydromorphone plasma concentration analysis from the ventral tail vein in bearded dragons and subcarapacial sinus in turtles before (time 0) hydromorphone administration and at 0.5, 1, 6, 12 and 24 hours. RESULTS: The half-life of hydromorphone administered at 0.5 and 1.0 mg kg-1 was 2.54 and 3.05 hours in bearded dragons and 2.67 and 2.01 hours in red-eared sliders, respectively. The maximum plasma concentrations for 0.5 and 1.0 mg kg-1 were 142 and 369 ng mL-1 in bearded dragons and 1610 and 5142 ng mL-1 in red-eared sliders, respectively. Peak plasma concentrations were detected at 30 minutes for both species. Hydromorphone administered at both dosages provided plasma concentrations of 13-14 ng mL-1 for at least 24 hours in bearded dragons and of 5-6 ng mL-1 for at least 12 hours in red-eared sliders. Clinical sedation was observed for up to 1 hour posthydromorphone (1.0 mg kg-1) administration for five of six bearded dragons characterized by low body carriage and decreased response to stimuli. No evidence of clinical sedation was observed in red-eared sliders at either dose. CONCLUSIONS AND CLINICAL RELEVANCE: Recommended dosing strategy for hydromorphone is 0.5 mg kg-1 administered SC every 24 hours in bearded dragons and every 12-24 hours in red-eared sliders.

HEMATOLOGIC AND PLASMA BIOCHEMICAL REFERENCE VALUES FOR JUVENILE GREEN-NAPED LORIKEETS ( TRICHOGLOSSUS HAEMATODUS HAEMATODUS).

The green-naped lorikeet ( Trichoglossus haematodus haematodus) is a small, brightly colored psittacine that is one of many subspecies of the rainbow lorikeet popular in captivity. Overall, the rainbow lorikeet population is declining but the wide range of subspecies means the population is classified as "least concern" by the International Union for Conservation of Nature. The goal of this study was to establish normal hematologic and plasma biochemical analyte reference intervals for juvenile green-naped lorikeets. Hematology and plasma biochemistry variables were determined for 102 clinically healthy, captive-born, juvenile (2-6 mo) green-naped lorikeets house at a single institution. This study is the first report for hematologic and plasma biochemical values for any Trichoglossus species.

Development of a method for the determination of hydromorphone in plasma by LC-MS.

A simple high-performance liquid chromatography method for the determination of hydromorphone in small volume plasma has been developed. Following solid-phase extraction using Oasis HLB cartridges, samples were separated by reverse-phase high-performance liquid chromatography on an Atlantis T3 4.6 × 150 mm column (3.0 µm) and quantified using mass spectrometry. The mobile phase was a mixture of water with 0.1% formic acid and acetonitrile with 0.1% formic acid (91:9). The standard curve ranged from 1 to 500 ng/mL. Intra- and Inter-assay variability for hydromorphone was <10%, and the average recovery was >90%. The LLOQ was 1 ng/mL. This method was successfully applied to the analysis of hydromorphone samples at this institution. This method could be useful to those investigators dealing with small sample volumes, particularly when conducting pharmacokinetic studies that require multiple sampling from the same animal.