Intraocular pressure (IOP) was measured with the TonoVet rebound tonometer in 10 raptor species, and possible factors affecting IOP were investigated. A complete ophthalmic examination was performed, and IOP was assessed in 2 positions, upright and dorsal recumbency, in 237 birds belonging to the families Accipitridae, Falconidae, Strigidae, and Tytonidae. Mean IOP values of healthy eyes were calculated for each species, and differences between families, species, age, sex, left and right eye, as well as the 2 body positions were evaluated. Physiologic fluctuations of IOP were assessed by measuring IOP serially for 5 days at the same time of day in 15 birds of 3 species. Results showed IOP values varied by family and species, with the following mean IOP values (mm Hg ± SD) determined: white-tailed sea eagle (Haliaeetus albicilla), 26.9 ± 5.8; red kite (Milvus milvus), 13.0 ± 5.5; northern goshawk (Accipiter gentilis), 18.3 ± 3.8; Eurasian sparrowhawk (Accipiter nisus), 15.5 ± 2.5; common buzzard (Buteo buteo), 26.9 ± 7.0; common kestrel (Falco tinnunculus), 9.8 ± 2.5; peregrine falcon, (Falco peregrinus), 12.7 ± 5.8; tawny owl (Strix aluco), 9.4 ± 4.1; long-eared owl (Asio otus), 7.8 ± 3.2; and barn owl (Tyto alba), 10.8 ± 3.8. No significant differences were found between sexes or between left and right eyes. In goshawks, common buzzards, and common kestrels, mean IOP was significantly lower in juvenile birds than it was in adult birds. Mean IOP differed significantly by body position in tawny owls (P  =  .01) and common buzzards (P  =  .04). By measuring IOP over several days, mean physiologic variations of ±2 mm Hg were detected. Differences in IOP between species and age groups should be considered when interpreting tonometric results. Physiologic fluctuations of IOP may occur and should not be misinterpreted. These results show that rebound tonometry is a useful diagnostic tool in measuring IOP in birds of prey because it provides rapid results and is well tolerated by birds.

To evaluate the pathologic effects of carprofen in a pigeon model (Columba livia), 52 young adult pigeons were used in a randomized control study design. Sixteen pigeons were randomly assigned to 1 of 3 treatment groups and received carprofen by intramuscular injection at dosages of either 2, 5, or 10 mg/kg once daily for 7 days. Four pigeons served as saline-injected controls. Four pigeons from each group and 1 control pigeon were randomly selected on days 2, 4, 6, and 8 to obtain blood samples and then were euthanatized and submitted for necropsy. Histologic lesions in pectoral muscle, liver, kidney, and digestive tract tissue samples were ranked in severity as 0, normal/not present; 1, minimal; 2, mild; 3, mild to moderate; 4, moderate; 5, moderate to marked; and 6, marked pathologic changes. Two-way analysis of variance (day × dose) and pairwise t tests revealed significant (P ≤ .05) mild decreases in total protein and glucose concentrations and marked increases in aspartate aminotransferase and alanine aminotransferase enzyme activities after carprofen treatments. Gross lesions in carprofen-treated pigeons were pale injection sites (23/48 [47.9%]), mottled yellow livers (9/48 [18.8%]), and congestion of small intestines (7/48 [14.6%]). Liver, kidney, and muscle injection sites had significantly increased (P ≤ .05) severity of histologic lesions. In pigeons, intramuscular administration of carprofen is associated with increased aspartate aminotransferase and alanine aminotransferase enzyme concentrations, gross lesions in muscle injection sites and liver, and histologic lesions in liver and muscle.

Previous studies have validated the clinical use of opioids with κ-receptor affinities for pain management in birds. Butorphanol, a κ opioid receptor agonist and a μ opioid receptor antagonist, is currently considered by many clinicians to be the opioid of choice for this use. However, despite studies reporting the analgesic properties of butorphanol in psittacine birds, dosing intervals have not been established for any psittacine species. The goals of this study in the Hispaniolan Amazon parrot (Amazona ventralis) were to evaluate the pharmacokinetics of butorphanol tartrate after intravenous (IV), intramuscular (IM), and oral (PO) administration and to determine the bioavailability of butorphanol tartrate after oral administration. Twelve Hispaniolan Amazon parrots were used in the study, with a complete-crossover experimental design and a 3-month period separating each part of the study. The birds were randomly assigned to 3 groups (n  =  4) for each stage. Butorphanol tartrate was administered once at a dose of 5 mg/kg in the basilic vein or pectoral muscles or as an oral solution delivered via feeding tube into the crop for the IV, IM, and PO studies, respectively. After butorphanol administration, blood samples were collected at 1, 5, 15, 30, 60, 90, 120, 180, and 240 minutes for the IV and IM studies and at 5, 15, 30, 60, 90, 120, 180, 240, and 300 minutes for the PO study. Because of the size limitation of the birds, naïve pooling of datum points was used to generate a mean plasma butorphanol concentration at each time point. For each study, birds in each group (n  =  4) were bled 3 times after dosing. Plasma butorphanol concentrations were determined by high-performance liquid chromatography/tandem mass spectrometry, and pharmacokinetic parameters were calculated. Butorphanol tartrate was found to have high bioavailability and rapid elimination following IM administration. In contrast, oral administration resulted in low bioavailability (<10%), thus precluding the use of this route of administration for clinical purposes. Based on these results, in Hispaniolan Amazon parrots, butorphanol tartrate dosed at 5 mg/kg IV or IM would have to be administered every 2 and 3 hours, respectively, to maintain plasma concentrations consistent with published therapeutic levels. To our knowledge, this is the first published study presenting the pharmacokinetic analysis of butorphanol tartrate in a psittacine species as well as the first study presenting pharmacokinetic analysis of butorphanol after oral administration in any avian species.

To be considered for release, raptors undergoing rehabilitation must have recovered from their initial injury in addition to being clinically healthy. For that purpose, a good understanding of reference hematologic values is important in determining release criteria for raptors in a rehabilitation setting. In this study, retrospective data were tabulated from clinically normal birds within 10 days of release from a rehabilitation facility. Hematologic values were compiled from 71 red-tailed hawks (Buteo jamaicensis), 54 Eastern screech owls (Megascops asio), 31 Cooper's hawks (Accipiter cooperii), 30 great-horned owls (Bubo virginianus), 28 barred owls (Strix varia), 16 bald eagles (Haliaeetus leucocephalus), and 12 broad-winged hawks (Buteo platypterus). Parameters collected included a white blood cell count and differential, hematocrit, and total protein concentration. Comparisons were made among species and among previously published reports of reference hematologic values in free-ranging birds or permanently captive birds. This is the first published report of reference values for Eastern screech owls, barred owls, and broad-winged hawks; and the first prerelease reference values for all species undergoing rehabilitation. These data can be used as a reference when developing release criteria for rehabilitated raptors.

An isolate of genotype 2 avian bornavirus (ABV) was recovered from a cockatiel (Nymphicus hollandicus) that was euthanatized for an unrelated lesion and showing no clinical evidence of proventricular dilatation disease (PDD). On histopathologic examination, mild inflammatory lesions were present in the heart and brain, but gastrointestinal lesions characteristic of classic PDD were not observed. To investigate if this ABV2 isolate had reduced virulence, the virus was propagated in duck embryo fibroblasts and inoculated into 2 adult cockatiels by the oral and intramuscular routes. One bird developed clinical signs on day 33 and was euthanatized on day 36. The second challenged bird developed clinical signs on day 41 and was euthanatized on day 45. At necropsy, the proventriculus of both birds was slightly enlarged. Histopathologic examination showed lesions typical of PDD in the brain, spinal cord, heart, adrenal gland, and intestine. A control, uninoculated cockatiel was apparently healthy when euthanatized on day 50. These results show that ABV2 is now the second ABV genotype to be formally shown to cause PDD.

Candida albicans is among the major agents of mucous membrane mycosis in humans and animals, with systemic and deep infections observed in immunocompromised hosts. We describe a case of fatal granulomatous myocarditis caused by C albicans in a 20-day-old canary (Serinus canaria). The etiologic diagnosis was confirmed by identifying characteristic morphologic features of the organism, combined with histochemical staining, and followed by the use of ad hoc biomolecular analysis.

A red-tailed hawk (Buteo jamaicensis) and a Canada goose (Branta canadensis) were evaluated for unilateral pelvic limb lameness. Physical examination findings and results of diagnostic imaging revealed femoral neck fractures in both birds. Both birds were treated with a femoral head and neck excision arthroplasty. The affected legs were not immobilized, and the birds were encouraged to use the legs immediately after surgery to encourage formation of a pseudoarthrosis. Within 2 weeks, both birds were using the affected limb well enough to be either successfully released or transferred to a wildlife rehabilitation facility. Femoral head and neck excision arthroplasty without immobilization of the limb is recommended for managing avian femoral neck fractures, especially in free-ranging species in which a rapid and complete or near complete return to function is vital for survival in the wild.

A 37-year-old female yellow-headed Amazon parrot (Amazona ochrocephala oratrix) was presented after a 4-month-period behavior change and intermittent episodes of obtunded mentation. Clinical findings on physical examination included ataxia, a weak grasp, and reluctance to move. Results of magnetic resonance imaging were consistent with severe hydrocephalus without evidence of cerebrospinal fluid obstruction. The bird was treated with tapering dosages of prednisolone over a 4-month period, during which time the episodes did not occur. Discontinuation of treatment was attempted several times but resulted in relapse. After 3.5 years of maintenance treatment with prednisolone, the bird was presented subsequent to a 5-hour episode of obtunded mentation and worsening neurologic signs. Despite increasing the dose of prednisolone and providing additional supportive care, the bird's condition worsened, and euthanasia was elected. Necropsy findings included severe hydrocephalus with significant loss of right cerebral parenchyma and no evidence of cerebrospinal fluid obstruction. Histologic examination of the remaining cerebral parenchyma revealed a moderate, multifocal, cellular infiltrate; encephalomalacia; fibrosis; and hemosiderosis in tissue adjacent to the distended ventricles. Other findings included hepatic vacuolar degeneration. Diagnostic imaging and postmortem findings were consistent with a diagnosis of hydrocephalus ex vacuo. To our knowledge, this is the first report of hydrocephalus in an Amazon parrot as well as the first report of hydrocephalus in any avian species associated with long-term follow-up and prolonged corticosteroid treatment.

The biodiversity crisis is often reported in the news today. As wildernesses become less wild, wildlife species become less present in the remaining wild spaces. Biodiversity is in decline. In fact, the rate of extinctions is currently estimated at 100–1000 times above the pre-human “baseline normal” levels, which has led many to propose that we are in a period of the sixth great extinction. The difference between this sixth extinction period and the previous 5 is that species are going extinct predominantly due to anthropogenic—human driven—impacts. The extinction of species is often related to habitat loss and degradation, wildlife trade, invasive species, and, in a growing number of cases, disease. Today 12% of bird species are threatened with extinction. That is 12%! Veterinarians in private practice (companion, exotic, and poultry), rehabilitation centers, zoological institutions, government agencies, and nongovernment conservation organizations work with avian patients. In this age of increasingly complex threats to the long-term conservation of endangered avian species and media coverage of zoonotic diseases with links to birds (eg, avian influenza, West Nile virus), the roles that veterinarians have in the care for individual patients and flocks, human health, and avian conservation are complex and variable.

I have invited 5 health and conservation professionals working in the field of avian health and conservation to discuss some of the hot topics in avian conservation and the role of veterinarians in this field. Participants are Christine V. Fiorello, DVM, PhD, Dipl ACZM, Response Veterinarian, Oiled Wildlife Care Network, Wildlife Health Center, School of Veterinary Medicine, University of California, Davis, Davis, CA, USA; J. Jill Heatley, DVM, MS, Dipl ABVP (Avian), Dipl ACZM, Associate Professor, Zoological Medicine, College of Veterinary Medicine, Texas A&M University, College Station, TX, USA; Kathryn P. Huyvaert, PhD, Assistant Professor, Department of Fish, Wildlife, and Conservation Biology, Colorado State University, Fort Collins, CO, USA; Peggy Shashy, DVM, Animal Medical Clinic at Sawgrass, Ponte Vedra Beach, FL, USA; and Kristine M. Smith, DVM, Dipl ACZM, Associate Director, Health and Policy, EcoHealth Alliance, New York, NY, USA. I hope that by hearing their perspectives, each of us may be able to more fully consider our roles to ensure the long term conservation of avian species.