Pharmacokinetics of a Sustained-release Formulation of Meloxicam After Subcutaneous Administration to Hispaniolan Amazon Parrots (Amazona ventralis)

Meloxicam has been shown to have a safe and favorable pharmacodynamic profile with individual variability in Hispaniolan Amazon parrots (Amazona ventralis). In the current study, we determined the pharmacokinetics of a sustained-release formulation of meloxicam after subcutaneous administration to Hispaniolan Amazon parrots. Twelve healthy adult parrots, 6 males and 6 females, were used in the study. Blood samples were collected before (time 0) and at 0.5, 1, 2, 6, 12, 24, 48, 72, 96, and 120 hours after a single dose of the sustained-release meloxicam formulation (3 mg/kg SC). Plasma meloxicam concentrations were measured by high-pressure liquid chromatography. Pharmacokinetic parameters were determined by noncompartmental analysis. Plasma concentrations reached a mean C_max of 23.4 μg/mL (range, 14.7-46.0 μg/mL) at 1.8 hours (range, 0.5-6 hours), with a terminal half-life of 7.4 hours (range, 1.4-40.9 hours). Individual variation was noticeable, such that some parrots (4 of 12 birds) had very low plasma meloxicam concentrations, similar to the high variability reported in a previous pharmacokinetic study of the standard meloxicam formulation in the same group of birds. Two birds developed small self-resolving scabs at the injection site. On the basis of these results, the sustained-release meloxicam formulation could be administered every 12 to 96 hours in Hispaniolan Amazon parrots to manage pain. Because of these highly variable results, the use of this formulation in this species cannot be recommended until further pharmacokinetic, safety, and pharmacogenomic evaluations are performed to establish accurate dosing recommendations and to understand the high pharmacokinetic variability.

Pharmacokinetics of butorphanol tartrate in a long-acting poloxamer 407 gel formulation administered to Hispaniolan Amazon parrots (Amazona ventralis)

OBJECTIVE To determine pharmacokinetics of butorphanol tartrate incorporated into poloxamer 407 (P407) after SC administration to Hispaniolan Amazon parrots (Amazona ventralis). ANIMALS 11 adult Hispaniolan Amazon parrots (6 males and 5 females; 11 to 27 years old). PROCEDURES A sterile formulation of butorphanol in P407 (But-P407) 25% (percentage determined as [weight of P407/weight of diluent] × 100]) was created (8.3 mg/mL). Five preliminary experiments (2 birds/experiment) were performed to determine the ideal dose for this species. The formulation then was administered (12.5 mg/kg, SC) to 8 birds. Blood samples were collected before (time 0) and 0.08, 0.5, 1, 2, 4, 8, 12, and 24 hours after drug administration. Some birds were used more than once, with a washout period of ≥ 3 months between subsequent treatments. Butorphanol concentrations were quantitated by use of liquid chromatography-tandem mass spectrometry. Pharmacokinetic analysis was performed by use of noncompartmental analysis. RESULTS Maximal plasma butorphanol concentration was reached at 1.31 hours. Plasma concentrations of butorphanol remained > 100 ng/mL for > 3 hours (all birds) or > 4 hours (5/8 birds) but < 8 hours (all birds). Half-life of the terminal slope was 3.41 hours. No adverse effects were detected. CONCLUSIONS AND CLINICAL RELEVANCE Butorphanol was absorbed well from the But-P407 25% by Hispaniolan Amazon parrots, and absorption followed a pharmacokinetic profile compatible with a sustained-release drug. A dose of 12.5 mg/kg, SC, would theoretically provide analgesia for 4 to 8 hours. No adverse effects were detected. Studies on the pharmacodynamics of this formulation are necessary to confirm the degree and duration of analgesia.

Rhabdomyolysis and Artifactual Increase in Plasma Bicarbonate Concentration in an Amazon Parrot (Amazona species)

A 7-year-old male Amazon parrot housed outdoors presented with acute collapse, marked lethargy, and open-mouth breathing. The patient had stiffness of the pectoral muscles, and petechiation and ecchymosis noted around the eyes and beneath the mandible. Laboratory data revealed markedly increased aspartate aminotransferase, creatine kinase, and lactate dehydrogenase activity consistent with rhabdomyolysis, as well as markedly increased plasma bicarbonate concentration. Marked clinical improvement and resolution of laboratory abnormalities occurred with fluid therapy, administration of a nonsteroidal anti-inflammatory medication, and husbandry modifications, including indoor housing and dietary alteration. A spurious increase in bicarbonate measurement as documented in equine and bovine cases of rhabdomyolysis also occurred in this avian patient and must be considered for accurate interpretation of acid-base status in exotic species presenting with consistent clinical signs.

Hematologic and Biochemical Values of Wild Red-Tailed Amazon Parrot (Amazona brasiliensis) Nestlings With Abnormal Clinical Examination in Rasa Island, Brazil

The red-tailed Amazon parrot (Amazona brasiliensis) is an endangered psittacine species, but little information is available about abnormal clinical findings and hematologic and biochemical values of this species, which are important for monitoring the health of this population. To determine hematologic and biochemical values for wild red-tailed parrot nestlings exhibiting abnormal clinical findings, 31 nestlings from the Rasa Island (Paraná State, Southern Brazil) were physically restrained for clinical examination and blood sample collection. On physical examination, 26 birds had mild abnormalities and 5 had severe disorders. Parrots were divided into 5 groups according to the following clinical findings: presence of ectoparasites (group 1), respiratory disorders (group 2), chronic skin lesions caused by fly larvae (group 3), beak disorders (group 4), and severe clinical signs (group 5). Abnormal hematologic and biochemical findings in the nestlings were high total protein in group 3; low values for hemoglobin and mean corpuscular hemoglobin concentration in group 4; low glucose concentration, high mean absolute heterophil count, and high heterophil : lymphocyte ratio in group 5; high concentrations of total plasma protein in groups 3 and 4; and high globulin concentration in groups 3 and 5. In general, the population assessed was in good condition. These results provide a guide to the expected clinical findings associated with hematologic and biochemical concentrations in a population of free-living parrots with abnormal clinical examination findings. The data support the conservation planning and health monitoring of the endangered red-tailed Amazon parrot.

Pharmacokinetics of Compounded Intravenous and Oral Gabapentin in Hispaniolan Amazon Parrots ( Amazona ventralis )

Neuropathic pain is a manifestation of chronic pain that arises with damage to the somatosensory system. Pharmacologic treatment recommendations for alleviation of neuropathic pain are often multimodal, and the few reports communicating treatment of suspected neuropathic pain in avian patients describe the use of gabapentin as part of the therapeutic regimen. To determine the pharmacokinetics of gabapentin in Hispaniolan Amazon parrots ( Amazona ventralis ), compounded gabapentin suspensions were administered at 30 mg/kg IV to 2 birds, 10 mg/kg PO to 3 birds, and 30 mg/kg PO to 3 birds. Blood samples were collected immediately before and at 9 different time points after drug administration. Plasma samples were analyzed for gabapentin concentration, and pharmacokinetic parameters were calculated with both a nonlinear mixed-effect approach and a noncompartmental analysis. The best compartmental, oral model was used to simulate the concentration-time profiles resulting from different dosing scenarios. Mild sedation was observed in both study birds after intravenous injection. Computer simulation of different dosing scenarios with the mean parameter estimates showed that 15 mg/kg every 8 hours would be a starting point for oral dosing in Hispaniolan Amazon parrots based on effective plasma concentrations reported for human patients; however, additional studies need to be performed to establish a therapeutic dose.

Hematologic and Total Plasma Protein Values in Free-Living Red-tailed Amazon Parrot Nestlings (Amazona brasiliensis) in Paraná State, Brazil

The red-tailed Amazon parrot (Amazona brasiliensis) is an endangered psittacid species that is endemic in the south and southeast Brazilian Atlantic coastal region. Hematologic evaluation is important to monitor the health of these birds, and information about laboratory values for this species is scarce. Hematologic and total plasma protein profiles were determined for 33 free-living nestling parrots in Paraná state, Brazil. Parrots were temporarily removed from the nest and manually restrained to record body weight and collect blood samples. Mean body weight was <400 g in 13 birds (group 1) and >400 g in 20 birds (group 2). Significantly higher levels of mean corpuscular hemoglobin concentrations, white blood cell counts, monocytes, and basophils were observed in younger birds (group 1). A stress leukogram (high white blood cell and heterophil count) was found in all nestlings, suggesting stress induced by capture and restraint. Parameters obtained in this study will be essential to assess the physiologic and pathologic condition of wild parrots, to evaluate the effects of environmental changes on their health, and to contribute to conservation efforts of this endangered species.

Plasma Drug Concentrations of Orally Administered Rosuvastatin in Hispaniolan Amazon Parrots (Amazona ventralis)

Atherosclerotic diseases are common in pet psittacine birds, in particular Amazon parrots. While hypercholesterolemia and dyslipidemia have not definitely been associated with increased susceptibility to atherosclerosis in parrots, these are important and well-known risk factors in humans. Therefore statin drugs such as rosuvastatin constitute the mainstay of human treatment of dyslipidemia and the prevention of atherosclerosis. No pharmacologic studies have been performed in psittacine birds despite the high prevalence of atherosclerosis in captivity. Thirteen Hispaniolan Amazon parrots were used to test a single oral dose of 10 mg/kg of rosuvastatin with blood sampling performed according to a balanced incomplete block design over 36 hours. Because low plasma concentrations were produced in the first study, a subsequent pilot study using a dose of 25 mg/kg in 2 Amazon parrots was performed. Most plasma samples for the 10 mg/kg dose and all samples for the 25 mg/kg dose had rosuvastatin concentration below the limits of quantitation. For the 10 mg/kg study, the median peak plasma concentration and time to peak plasma concentration were 0.032 μg/mL and 2 hours, respectively. Our results indicate that rosuvastatin does not appear suitable in Amazon parrots as compounded and used at the dose in this study. Pharmacodynamic studies investigating lipid-lowering effects of statins rather than pharmacokinetic studies may be more practical and cost effective in future studies to screen for a statin with more ideal properties for potential use in psittacine dyslipidemia and atherosclerotic diseases.

A survey of selected parasitic and viral pathogens in four species of Mexican parrots, Amazona autumnalis, Amazona oratrix, Amazona viridigenalis, and Rhynchopsitta pachyrhyncha

Isolated populations of four species of Mexican parrots were sampled for evidence of selected pathogens of concern in birds originating in Latin America. Data were collected between June and September 1997, and ectoparasite collection was repeated with Rhynchopsitta pachyrhyncha in September 2000. Serum samples from nine Amazona oratrix, 10 Amazona viridigenalis, 6 Amazona autumnalis, and 25 R. pachyrhyncha chicks were screened for neutralizing antibodies to psittacid herpesvirus and avian influenza and for antibodies to paramyxovirus serotypes 1 and 3. Chicks were also examined visually for fecal parasites and ectoparasites. All serologic and fecal parasite tests were negative. Ectoparasites included ticks, Ixodidae; mites, Ornithonyssus sylviarum; fleas, Psyttopsylla mexicana; lice, Paragoniocotes mexicanus, Heteromenopon sp., and Psittacobrosus sp.; and bugs, Ornithocoris sp. This study provides baseline information to guide future health studies.

Serum concentrations and analgesic effects of liposome-encapsulated and standard butorphanol tartrate in parrots

OBJECTIVE

To compare serum concentrations of liposome-encapsulated butorphanol tartrate (LEBT) and standard butorphanol tartrate (STDBT) following SC and IM administration, respectively, and to evaluate analgesic effects of LEBT and STDBT after parenteral administration to Hispaniolan parrots.

ANIMALS

11 adult Hispaniolan parrots.

PROCEDURE

The ability of LEBT to prolong the duration of analgesia in an avian species was tested. Blood samples were collected at serial time points after SC administration of LEBT (10 mg/kg or 15 mg/kg) or IM administration of STDBT (5 mg/kg). Serum concentrations of butorphanol tartrate were determined by use of a commercial immunoassay that measured parent drug and metabolites. Analgesic efficacy was evaluated in parrots exposed to electrical and thermal stimuli. Foot withdrawal thresholds were recorded at baseline and at serial time points after LEBT (15 mg/kg), liposome vehicle, STDBT (2 mg/kg), or physiologic saline (0.9% NaCl) solution administration.

RESULTS

LEBT had a prolonged in vivo release for up to 5 days. Negligible serum butorphanol and butorphanol metabolite concentrations were obtained at 24 hours after IM administration of STDBT. Analgesic efficacy of LEBT as measured by foot withdrawal threshold to noxious thermal and electrical stimuli persisted for 3 to 5 days following SC administration of LEBT.

CONCLUSIONS AND CLINICAL RELEVANCE

SC administration of LEBT provided analgesia and detectable serum butorphanol concentrations in Hispaniolan parrots for up to 5 days. The use of LEBT may allow for substantial improvement in long-term pain relief without subjecting birds to the stress of handling and multiple daily injections.

Comparison of biochemical values in serum and plasma, fresh and frozen plasma, and hemolyzed samples from orange-winged Amazon parrots (Amazona amazonica)

BACKGROUND

To the authors' knowledge, on the basis of sample type, storage condition, or hemolysis, differences in serum and plasma biochemical values have not been evaluated in orange-winged Amazon parrots (Amazona amazonica).

OBJECTIVES

The purpose of this study was to compare values for biochemical analytes in serum vs plasma, fresh vs frozen plasma, and nonhemolyzed vs hemolyzed samples in orange-winged Amazon parrots. We also compared differences in serum and plasma yield from whole-blood aliquots.

METHODS

Fifteen biochemical analytes were evaluated in paired serum and plasma, fresh and frozen plasma, nonhemolyzed and hemolyzed serum and plasma samples from orange-winged Amazon parrots (n = 10) using a wet reagent analyzer. Hemolysis was assessed qualitatively (visually) and quantitatively (hemoglobin [Hgb] measured spectrophotometrically). Serum and plasma yields from 500-microl whole-blood aliquots were determined from centrifuged samples.

RESULTS

Analyte values significantly differed among sample groups, but were still within published reference intervals, with the exception of increases in potassium concentration in markedly hemolyzed serum and plasma samples. Clinically important changes in hemolyzed serum and plasma samples included increases in potassium, phosphorus, and albumin concentrations and lactate dehydrogenase activity. The degree of hemolysis assigned qualitatively did not correlate with quantitative Hgb concentration. A significantly greater yield of plasma (288 +/- 13 microL) than serum (241 +/- 44 microL) was obtained.

CONCLUSIONS

Significant differences may occur in different sample types, however, only changes in potassium, phosphorus, albumin, and lactate dehydrogenase values in hemolyzed samples were considered clinically relevant. Lack of agreement between qualitative and quantitative Hgb concentration indicates the unreliability of visual estimation. Based on higher sample yield, and lack of clinically relevant differences from serum, plasma is a better sample choice for clinical chemistry analysis in birds.

HEALTH EVALUATION OF FREE-RANGING AND CAPTIVE BLUE‐FRONTED AMAZON PARROTS (AMAZONA AESTIVA) IN THE GRAN CHACO, BOLIVIA

Bolivia has a total of 47 species of Psittacidae, seven of which have been identified in our study site, the semiarid Gran Chaco of the Isoso. One species, the blue-fronted parrot (Amazona aestiva), is frequently captured by local Isoseño Guaraní Indians for exploitation on the national and international market. These birds are often temporarily housed in small villages under unhygienic conditions with poultry and other domestic species. On occasion, these parrots escape back to the wild. Additionally, many of these birds are kept as pets or are used to lure wild. parrots within slingshot range for subsequent capture. In this study, we evaluated the health status, including the level of exposure to selected infectious agents, in the wild-caught captive birds and free-ranging birds. Physical examinations were performed, and blood was collected, from 54 live birds (20 captive and 34 free-ranging). Feces were collected from 15 birds (seven captive and eight free-ranging). Necropsies were also performed on four recently dead wild-caught birds. On serologic testing, no birds were found to have antibodies to avian influenza virus, Chlamydophila psittaci, infectious bronchitis virus, infectious bursal disease virus, infectious laryngotracheitis virus, Marek's disease virus, paramyxovirus-1, paramyxovirus-2, paramyxovirus-3, polyomavirus, eastern equine encephalitis virus, western equine encephalitis virus, or Venezuelan equine encephalitis virus. Positive antibody titers were found for psittacine herpesvirus (8/44, 18.2%), Aspergillus spp. (3/51, 5.9%), and Salmonella pullorum (33/49, 67.3%). All three of the birds that tested antibody positive for Aspergillus spp. were captive, whereas six of the eight and 15 of the 33 birds that tested positive for psittacine herpesvirus and S. pullorum, respectively, were wild.