Guy Fitzgerald

Second generation anticoagulant rodenticides in predatory birds: Probabilistic characterisation of toxic liver concentrations and implications for predatory bird populations in Canada.

Second-generation anticoagulant rodenticides (SGARs) are widely used to control rodent pests but exposure and poisonings occur in non-target species, such as birds of prey. Liver residues are often analysed to detect exposure in birds found dead but their use to assess toxicity of SGARs is problematic. We analysed published data on hepatic rodenticide residues and associated symptoms of anticoagulant poisoning from 270 birds of prey using logistic regression to estimate the probability of toxicosis associated with different liver SGAR residues. We also evaluated exposure to SGARs on a national level in Canada by analysing 196 livers from great horned owls (Bubo virginianus) and red-tailed hawks (Buteo jamaicensis) found dead at locations across the country. Analysis of a broader sample of raptor species from Quebec also helped define the taxonomic breadth of contamination. Calculated probability curves suggest significant species differences in sensitivity to SGARs and significant likelihood of toxicosis below previously suggested concentrations of concern (<0.1mg/kg). Analysis of birds from Quebec showed that a broad range of raptor species are exposed to SGARs, indicating that generalised terrestrial food chains could be contaminated in the vicinity of the sampled areas. Of the two species for which we had samples from across Canada, great horned owls are exposed to SGARs to a greater extent than red-tailed hawks and the liver residue levels were also higher. Using our probability estimates of effect, we estimate that a minimum of 11% of the sampled great horned owl population is at risk of being directly killed by SGARs. This is the first time the potential mortality impact of SGARs on a raptor population has been estimated.

Analgesic effects of meloxicam administration on postoperative orthopedic pain in domestic pigeons (Columba livia)

OBJECTIVE To assess the analgesic effects of 2 doses of meloxicam on the degree of postoperative orthopedic pain in pigeons. ANIMALS 21 domestic pigeons (Columba livia). PROCEDURES In each bird, a standardized osteotomy of 1 femur was performed and the fracture was immobilized with an intramedullary pin. Birds were randomly allocated to receive saline (0.9% NaCl) solution (control) or meloxicam (0.5 mg/kg [low dose] or 2.0 mg/kg [high dose]). The first treatment was administered i.m. after surgery was completed. Subsequent treatments were administered p.o. every 12 hours for 9 days. Degree of postoperative pain was assessed for the first 4 days after surgery by use of 3 methods: an electronic perch for assessment of weight-bearing load differential of the pelvic limbs, 4 pain scales, and analysis of video-recorded partial ethograms for bird activity and posture. RESULTS No significant differences were observed between the control group and the low-dose meloxicam group in any tested variable. The high-dose meloxicam group had a greater degree of weight bearing on the affected limb from the second to the fourth postoperative day as well as lower pain scores for at least the first 2 postoperative days, compared with the other groups. Return to presurgical behavior was achieved faster in pigeons that received high-dose meloxicam than in the other groups. No adverse effects were observed. CONCLUSIONS AND CLINICAL RELEVANCE Administration of meloxicam at 0.5 mg/kg appeared ineffective in minimizing postoperative orthopedic pain in pigeons, but the 2.0 mg/kg dose provided quantifiable analgesia that appeared safe in this species in experimental conditions.

MONITORING OF THE VENTILATORY STATUS OF ANESTHETIZED BIRDS OF PREY BY USING END-TIDAL CARBON DIOXIDE MEASURED WITH A MICROSTREAM CAPNOMETER

Abstract The relationship between end-tidal partial pressure of carbon dioxide (PETCO2), arterial partial pressure of carbon dioxide (PaCO2), and blood pH in isoflurane-anesthetized raptors was evaluated. PaCO2 and pH were determined in serial arterial samples from isoflurane anesthetized birds and compared with concurrent end-tidal partial pressure of carbon dioxide measured with a Microstream sidestream capnograph. Forty-eight paired samples, taken from 11 birds of prey (weighing 416–2,062 g), were used to determine correlations coefficients between PaCO2 and PETCO2, and between PETCO2 and pH. Limits of agreement between PaCO2 and PETCO2 also were calculated. Strong correlations were observed between PaCO2 and PETCO2 (r = 0.94; P < 0.0001) as well as between PETCO2 and pH (r = −0.90; P < 0.0001). However, the level of agreement between PaCO2 and PETCO2 varied considerably. Low values of PETCO2, ranging from 18 to 29 mm Hg, exceeded the concomitantly measured values of PaCO2 by an average of 6.0 mm Hg (6.0 ± 1.9 mm Hg; mean ± SD). Conversely, high values of PETCO2, ranging from 50 to 63 mm Hg, were on average 7.6 mm Hg (7.6 ± 9.8 mm Hg) lower than values of PaCO2. In the 30 to 49 mm Hg range for PETCO2, the difference between PETCO2 and PaCO2 was on average 1.0 mm Hg (1.0 ± 8.5 mm Hg). These results suggest that the capnograph used provided a sufficiently accurate estimation of arterial partial pressure of carbon dioxide for birds weighing >400 g and receiving manual positive ventilation with a Bain system. In our study, the linear relationship observed between the pH and the end-tidal partial pressure of carbon dioxide suggested that the monitoring of end-tidal partial pressure of carbon dioxide also can be useful to prevent respiratory acidosis.

Evaluation of a fracture pain model in domestic pigeons (Columba livia)

OBJECTIVE To validate a model of postfracture pain in perching birds. ANIMALS 21 adult domestic pigeons (Columba livia). PROCEDURES In each bird, a standardized osteotomy of 1 femur was performed and the fracture was immobilized with an intramedullary pin. Degree of postoperative pain was evaluated 6 times/d for 4 days by use of 3 methods: an electronic perch for assessment of weight-bearing load differential of the pelvic limbs, 4 numeric rating pain scales for assessment of pain (all of which involved the observer in the same room as the bird), and analysis of video-recorded (observer absent) partial ethograms for bird activity and posture. Measurements obtained were compared with data collected before the surgery to evaluate the ability of these methods to detect pain. RESULTS The weight-bearing load differential was a sensitive, specific, reliable, and indirect measure of fracture-associated pain in the model used. Two of 4 tested pain scales (fractured limb position and subjective evaluation of degree of pain) were sensitive and specific for detecting pain and were reliable in a research setting. Interobserver reliability of the 4 pain scales was excellent. Partial ethograms were sensitive for identifying pain-associated behavior in pigeons, particularly during the first 2 days after surgery. CONCLUSIONS AND CLINICAL RELEVANCE The fracture pain model was reliable and reproducible and may be useful for experimental studies involving postsurgical pain in pigeons. Weight-bearing load differential was the most sensitive and specific means of determining degree of pain in pigeons during the first 4 days after hind limb fracture induction.

Evaluation of High Dosages of Oral Meloxicam in American Kestrels (Falco sparverius)

Abstract To evaluate the toxicity of short-term high doses of meloxicam in American kestrels (Falco sparverius), 32 male captive-born, 1- to 4-year-old American kestrels were randomly assigned to 4 groups: 3 groups treated with meloxicam (n = 9 per group) and a control group (n = 5). Meloxicam was administered orally via feeding tube in the proventriculus at 2, 10, and 20 mg/kg every 12 hours for 7 days for the treatment groups, while the control group received saline solution. The birds were evaluated for the presence of clinical signs, abnormalities in the complete blood cell count and in the plasma biochemical panel for the 20-mg/kg group, and gross and histopathologic lesions. No clinical signs or mortality were observed in any group. No significant differences of clinical relevance were found in results of the packed cell volume, total solids, and biochemical panel, and no evidence of renal toxicity was found in the treatment or control groups. A significant correlation was found between hepatic lipidosis and meloxicam dose (P = .02). Two of 9 birds in the 20-mg/kg group developed gastric ulcers, although this result was not significant. None of the birds in the 2- and 10-mg/kg groups had similar lesions. Finally, meloxicam dosages up to 20 mg/kg did not result in nephrotoxicity in American kestrels. Further toxicologic studies to evaluate hepatotoxicity and gastrotoxicity of meloxicam in avian species are needed.

ASSESSMENT OF REGROWTH OF FLIGHT FEATHERS AFTER MANUAL REMOVAL IN AMERICAN KESTRELS (FALCO SPARVERIUS)

Abstract:  The objective of this study was to evaluate if extraction of broken feathers outside the molting period was an efficient method to induce growth of new flight feathers as part of the rehabilitation process of raptors with damaged plumage. Primaries, secondaries, and rectrices (four of each) were removed under general anesthesia from 10 American kestrels (Falco sparverius) using two different protocols: with and without filling the follicle with bismuth subnitrate (Orbeseal) to prevent it from sealing. Birds were kept in large aviaries under natural daylight and outdoor temperatures. Rate and quality of growth of new feathers were assessed regularly for 4 mo. Results were significantly different between the types of feathers: 100% of rectrices, 58% of secondaries, and 8% of primaries started to grow within the 4 winter months, and 95% of rectrices, 30% of secondaries, and 0% of primaries completed their growth normally within this period. The use of Orbeseal did not improve the outcome. The tail feathers began to grow between the second and third weeks at about 2.7 mm/day, and growth was completed within 7 wk. Rate, starting time, and duration of remigial growth were less predictable and varied widely among individuals. Although the exact impact of these extractions on the natural molt is still unclear, most of the primaries that were plucked during this study failed to regrow normally during the following molt. In conclusion, plucking damaged tail feathers in kestrels can successfully decrease the duration of rehabilitation. However, this procedure would not be recommended for wing feathers.

Fatal aerosacculitis and pneumonia associated with Eucoleus sp. (nematoda: capillaridae) in the lungs of a Peregrine Falcon (Falco peregrinus).

A Peregrine Falcon (Falco peregrinus) died of verminous and bacterial pneumonia and aerosacculitis associated with capillarid nematodes of the genus Eucoleus. This represents an aberrant location for these helminths in avian hosts. Although positive identification was not possible, the worms resembled Eucoleus aerophilus, a species not reported previously from birds.

Surgical Repair of Acquired Ankyloblepharon in a Cockatiel (Nymphicus hollandicus)

ABSTRACT Eyelid anomalies caused by congenital or acquired etiologies occur in birds. A cockatiel (Nymphicus hollandicus) was presented for evaluation of fused eyelids on the right side and a narrowed palpebral fissure on the left side after a burn accident. The right eyelids were reconstructed, and the left palpebral fissure was lengthened by using microsurgical techniques. The cockatiel regained a normal appearance after surgery, and corneal disease was prevented.

CorrigendumCorrigendum to “Second generation anticoagulant rodenticides in predatory birds: Probabilistic characterisation of toxic liver concentrations and implications for predatory bird populations in Canada” [Environ. Int. 37 (2011) 914–920]

a National Wildlife Research Centre, Science & Technology Branch, Environment Canada, Ottawa, Ontario, Canada K1A 0H3 b Centre for Ecology & Hydrology, Lancaster Environment Centre, Library Avenue, Bailrigg, Lancaster LA1 4AP, UK c Science & Technology Branch, Environment Canada, Ste-Foy, QC, Canada G1V 4H5 d Science & Technology Branch, Environment Canada, Burlington, ON, Canada L7R 4A6 e Canadian Wildlife Service, Environment Canada, Delta, BC, Canada V4K 3N2 f Universite de Montreal, Saint-Hyacinthe, QC, Canada J2S 7C6 g Science & Technology Branch, Environment Canada, Delta, BC, Canada V4K 3N2

Preliminary Findings of Structure and Expression of Opioid Receptor Genes in a Peregrine Falcon (Falco peregrinus), a Snowy Owl (Bubo scandiacus), and a Blue-fronted Amazon Parrot (Amazona aestiva)

Abstract To further knowledge of the physiology of opioid receptors in birds, the structure and expression of the μ-, δ-, and κ-opioid receptor genes were studied in a peregrine falcon (Falco peregrinus), a snowy owl (Bubo scandiacus), and a blue-fronted Amazon parrot (Amazona aestiva). Tissue samples were obtained from birds that had been euthanatized for poor release prognosis or medical reasons. Samples were taken from the brain (telencephalon, thalamus, pituitary gland, cerebellum, pons, medulla oblongata, mesencephalon), the spinal cord and dorsal root ganglions, and plantar foot skin. Messenger RNA was recovered, and reverse transcription polymerase chain reaction (RT-PCR) was performed to generate complementary DNA (cDNA) sequences. Gene structures were documented by directly comparing cDNA sequences with recently published genomic sequences for the peregrine falcon and the blue-fronted Amazon parrot or by comparisons with genomic sequences of related species for the snowy owl. Structurally, the avian μ-opioid receptor messenger RNA (mRNA) species were complex, displaying differential splicing, alternative stop codons, and multiple polyadenylation signals. In comparison, the structure of the avian κ-receptor mRNA was relatively simple. In contrast to what is seen in humans, the avian δ-receptor mRNA structure was found to be complex, demonstrating novel 3-prime coding and noncoding exons not identified in mammals. The role of the δ-opioid receptor merits further investigation in avian species.