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At least 289 records · Page 16Linked to original sources
PubMed2006

Passive West Nile virus antibody transfer from maternal Eastern screech-owls (Megascops asio) to progeny.

Transovarial antibody transfer in owls has not been demonstrated for West Nile virus (WNV). We sampled chicks from captive adult WNV-antibody-positive Eastern Screech-Owls (Megascops asio) to evaluate the prevalence of transovarial maternal antibody transfer, as well as titers and duration of maternal antibodies. Twenty-four owlets aged 1 to 27 days old circulated detectable antibodies with neutralizing antibody titers ranging from 20 to 1600 (median 1:40). Demonstrating that WNV antibodies are passively transferred transovarially is important for accurate interpretation of serologic data from young birds.

Animals↗
PubMed2000

Pharmacokinetics of piperacillan after intramuscular injection in red-tailed hawks (Buteo jamaicensis) and great horned owls (Bubo virginianus).

This study characterized and compared the pharmacokinetics of piperacillin after single 100 mg/kg i.m. injections in nine red-tailed hawks (Buteo jamaicensis) and five great horned owls (Bubo virginianus) over 48 hr by a modified agar well diffusion microbial inhibition assay. The mean maximum plasma piperacillin concentrations were 204 microg/ml and 221 microg/ml for the hawks and owls, respectively, and times of maximum concentrations were 15 min and 30 min, respectively. The calculated mean terminal elimination half-lives were 77 min in the hawks and 118 min in the owls. Area-under-the-curve values were 218 +/- 52 microg x hr/ml in the hawks and 444 +/- 104 microg x hr/ml in the owls. On the basis of the most common minimal inhibitory concentration (90%) for various bacterial isolates from clinical samples of 8 microg/ml, analysis of the data suggests that the maximum dosing interval for piperacillin at 100 mg/kg in medium sized raptors should be 4-6 hr.

Animals↗
PubMed2001

A modified protocol for sex identification of in ovo avian embryos and its application as a management tool for endangered species conservation programs.

A simple, reliable, and safe protocol was developed for the collection of small amounts of blood from avian eggs of variable size and at early stages of development. Fifty eggs were used in the study; 40 were common chicken (Gallus domesticus) eggs, six were homing pigeon (Columba livia domestica) eggs, and four were burrowing owl (Athene cunicularia) eggs. Collection was attempted approximately halfway through incubation. The success rate for collection of blood or blood-tinged fluid from eggs was high, averaging 68% in the chicken eggs, 100% in the homing pigeon eggs, and 75% in the burrowing owl eggs. Collection did not affect subsequent hatchability. This blood could then be used to determine the sex of the embryo by utilizing a DNA probe or restriction fragment length polymorphism technique. Sex identification in ovo allowed the demographic management of small populations of birds within our institution.

Animals↗
PubMed2006

Interactive effects of prey and p,p'-DDE on burrowing owl population dynamics.

We used population models to explore the effects of the organochlorine contaminant p,p'-DDE and fluctuations in vole availability on the population dynamics of Burrowing Owls (Athene cunicularia). Previous work indicated an interaction between low biomass of voles in the diet and moderate levels of p,p'-DDE in Burrowing Owl eggs that led to reproductive impairment. We constructed periodic and stochastic matrix models that incorporated three vole population states observed in the field: average, peak, and crash years. We modeled varying frequencies of vole crash years and a range of impairment of owl demographic rates in vole crash years. Vole availability had a greater impact on owl population growth rate than did reproductive impairment if vole populations peaked and crashed frequently. However, this difference disappeared as the frequency of vole crash years declined to once per decade. Fecundity, the demographic rate most affected by p,p'-DDE, had less impact on population growth rate than adult or juvenile survival. A life table response experiment of time-invariant matrices for average, peak, and crash vole conditions showed that low population growth under vole crash conditions was due to low adult and juvenile survival rates, whereas the extremely high population growth under vole peak conditions was due to increased fecundity. Our results suggest that even simple models can provide useful insights into complex ecological interactions. This is particularly valuable when temporal or spatial scales preclude manipulative experimental work in the field or laboratory.

Animals↗
PubMed2000

Electrodiagnostic evaluation of peripheral nerve function in rheas and barred owls.

OBJECTIVE: To establish reference values for electrodiagnostic evaluation of peripheral nerve function in birds. ANIMALS: 6 rheas and 6 barred owls. PROCEDURE: Birds were anesthetized with propofol or isoflurane in oxygen. Using a computer-based electromyograph system and needle electrodes for stimulation and recording, electromyography (EMG) was performed on the pectoral, biceps brachialis, and gastrocnemius muscles, and evoked EMG was performed on the tibial and ulnar nerves. Motor nerve conduction velocity (MNCV) was calculated. Repetitive stimulation was performed on these 2 nerves. Late F waves were recorded for each nerve, when possible. RESULTS: Activity was evident during insertion of the electrodes, but muscles tested were electrically quiescent after spontaneous EMG. Motor nerve conduction velocity was faster in the tibial nerve than ulnar nerve but did not differ significantly between species. Mean +/- SEM MNCV was 132.3+/-7.8 m/s for the tibial nerve and 59.7+/-7.8 m/s for the ulnar nerve. A significant difference was not observed in responses at the fourth or ninth stimulation during repetitive stimulation. Subsequent to the initial stimulation, amplitudes were +/-22.7% of the initial motor potential amplitude. Recorded F waves were inconsistent, which may have been associated with technique. CONCLUSIONS AND CLINICAL RELEVANCE: Reference range (mean +/-2 SEM) for MNCV was 34.1 to 75.3 m/s for the ulnar nerve and 116.7 to 147.9 m/s for the tibial nerve in barred owls and rheas. After repetitive stimulation, motor potential amplitudes may be +/-22.7% of the initial amplitude response.

Animals↗
PubMed2004

West Nile virus outbreak in North American owls, Ontario, 2002.

From July to September 2002, an outbreak of West Nile virus (WNV) caused a high number of deaths in captive owls at the Owl Foundation, Vineland, Ontario, Canada. Peak death rates occurred in mid-August, and the epidemiologic curve resembled that of corvids in the surrounding Niagara region. The outbreak occurred in the midst of a louse fly (Icosta americana, family Hippoboscidae) infestation. Of the flies tested, 16 (88.9 %) of 18 contained WNV RNA. Species with northern native breeding range and birds >1 year of age were at significantly higher risk for WNV-related deaths. Species with northern native breeding range and of medium-to-large body size were at significantly higher risk for exposure to WNV. Taxonomic relations (at the subfamily level) did not significantly affect exposure to WNV or WNV-related deaths. Northern native breeding range and medium-to-large body size were associated with earlier death within the outbreak period. Of the survivors, 69 (75.8 %) of 91 were seropositive for WNV.

Animals↗
PubMed2004

Detecting West Nile virus in owls and raptors by an antigen-capture assay.

We evaluated a rapid antigen-capture assay (VecTest) for detection of West Nile virus in oropharyngeal and cloacal swabs, collected at necropsy from owls (N = 93) and raptors (N = 27). Sensitivity was 93.5%-95.2% for northern owl species but <42.9% for all other species. Specificity was 100% for owls and 85.7% for raptors.

Animals↗
PubMed2000

The mucinous layer of corneal endothelial cells.

PURPOSE: The goal of this study was to characterize the morphology of the mucinous layer on rabbit, bovine, owl, and human corneal endothelial cells. METHODS: Corneoscleral buttons were fixed using cetylpyridinium chloride to stabilize "mucus" and the tissue was prepared for transmission electron microscopy. Photomicrographs were measured to determine the thickness of the endothelial and epithelial mucinous layer in the central cornea. RESULTS: The endothelial mucinous layer was seen as a nearly uniform electrodense region on the apical aspect of the endothelium. It was found to be 0.9 microm, 0.9 microm, 0.9 microm, and 0.5 microm thick in rabbit, bovine, owl, and human, respectively. The owl endothelium had an additional less electrodense layer with a granular appearance and a thickness of about 200 microm. The mucinous layer on the epithelium was similar in appearance to that on the endothelium and across species. CONCLUSIONS: The morphologic similarity of the endothelial and epithelial mucinous layers is a serendipitous finding that should prove valuable in experimental design. Ultimately, it is hoped that studies of the posterior corneal surface will deepen our knowledge of endothelial protection.

Adult↗
PubMed1976

Experimental rabies in a great horned owl.

A great horned owl (Bubo virginianus) was fed the carcass of an experimentally infected rabid skunk. The bird developed antibody titer to rabies, detected by passive haemagglutination, 27 days after oral inoculation by ingestion. The owl suppressed the infection until corticosteroid administration, after which a maximum antibody titer was attained. Evidence of active rabies viral infection was seen by fluorescent antibody staining of oral swabs, corneal impression smears and histologic tissue smears, by suckling mouse inoculation of oral swab washings, and by transmission electron microcopy. No clinical signs of rabies virus infection were observed.

Animals↗
PubMed1999

Synovial chondromatosis in raptors.

Fourteen raptors, consisting of 13 great horned owls (Bubo virginianus) and one red-tailed hawk (Buteo jamaicensis), from central and north central Minnesota, western Wisconsin, and eastern South Dakota (USA) were admitted to a raptor rehabilitation center between June 1992 and June 1995, with perisynovial and synovial chondromatosis affecting multiple joints. Birds were severely debilitated primarily due to loss of shoulder motion. The etiology of these lesions in raptors is unknown.

Animals↗
PubMed2002

Fatal spirochetosis due to a relapsing fever-like Borrelia sp. in a northern spotted owl.

Acute septicemic spirochetosis was diagnosed in an adult male northern spotted owl (Strix occidentalis caurina) found dead in Kittitas County, Washington, USA. Gross necropsy findings included marked enlargement of the liver and spleen and serofibrinous deposits on the serous membranes lining the body cavities and the pericardial and perihepatic sacs. Microscopic observations included macrophage infiltration in the liver and spleen with mild thrombosis and multifocal necrosis, as well as hemorrhage and acute inflammation in the choroid plexus of the brain. No viruses or pathogenic bacteria were isolated from brain, liver, or spleen, and no parasites were found in blood smears or impression smears of the liver. Chlamydial culture attempts were unsuccessful and no chlamydial antibodies were detected in serum. In silver-stained microscopic sections and by transmission electron microscopy of liver, numerous long, thin, spiral-shaped bacteria were seen in the liver, spleen, cerebral ventricles, and within blood vessels in many organs. The organism was identified as a member of the Borrelia genus by sequence analysis of the PCR-amplified 16S rRNA gene. The most closely related species is B. hermsii, an agent of relapsing fever in humans in the western United States. This is the first report of a relapsing fever-related Borrelia in a wild bird.

Animals↗
PubMed2003

Newcastle disease virus and Chlamydia psittaci in free-living raptors from eastern Germany.

Organ samples from free-living raptors from the federal states of Berlin and Brandenburg in eastern Germany were tested for Newcastle disease virus (NDV; n = 331) and Chlamydia psittaci (n = 39) by polymerase chain reaction (PCR). In 18 individuals NDV nucleic acids were detected. These samples originated from barn owls (Tyto alba; n = 15, 28%), tawny owl (Strix aluco; n = 1, 5%), common buzzard (Buteo buteo, n = 1, 1%), and European kestrel (Falco tinnunculus; n = 1, 4%). In 29 (74%) of 39 samples C. psittaci was detected. Chlamydia psittaci is common in free-living birds of prey in the investigated area.

Animals↗
PubMed2006

West Nile virus in raptors from Virginia during 2003: clinical, diagnostic, and epidemiologic findings.

Sixty-one birds of prey admitted to The Wildlife Center of Virginia (WCV; Waynesboro, Virginia, USA) from June to November 2003 were tested for West Nile virus (WNV) infection. Choanal and/or cloacal swabs were obtained and submitted to Virginia's Division of Consolidated Laboratory Services (Richmond, Virginia, USA) for analysis with real-time reverse transcriptase polymerase chain reaction (RT-PCR). Forty birds of prey were positive for WNV by RT-PCR. Five avian families and nine species of raptors were represented, with great horned owls (Bubo virginianus) and red-tailed hawks (Buteo jamaicensis) most frequently affected. Presenting clinical signs were consistent with previous reports of WNV infection in raptors; however, these differed between species. Of WNV positive birds, nonspecific signs of illness were the most common clinical findings, particularly in red-tailed hawks; signs included dehydration (n = 20), emaciation (n = 18), and depression (n = 15). Neurologic abnormalities were frequently identified, especially in great horned owls, and included head tremors (n = 17), ataxia (n = 13), head incoordination (n = 7), torticollis (n = 3), nystagmus (n = 3), and head tilt (n = 3). Great horned owls exhibited anemia and leukocytosis with heterophilia, eosinophilia, and monocytosis consistent with chronic inflammation. Red-tailed hawks were anemic with a heterophilic leukocytosis and regenerative left shift. The majority of WNV cases occurred during August and September; there was a marked increase in the number of raptors admitted to WCV during these months followed by a marked decrease during October, November, and December. This pattern differed from mean monthly admissions during the previous 10 years and suggests a negative impact on local raptor populations. The effects of WNV on avian populations are largely unknown; however, because of their ecological importance, further investigation of the effects of WNV on raptor populations is warranted.

Animals↗
PubMed2006

Isolation of Salmonella Enteritidis phage type 21b from a Eurasian eagle-owl (Bubo bubo).

A case of fatal salmonellosis in a Eurasian eagle-owl (Bubo bubo) from Bursa Province (northwestern Turkey) is described. The organs of the bird were examined histopathologically and microbiologically. Macroscopic and microscopic findings were consistent with a Salmonella infection. Salmonella enterica subspecies enterica serovar Enteritidis (S. Enteritidis) phage type (PT) 21b was isolated from the liver and spleen in pure culture and from the intestine. The isolate was susceptible to amoxycillin/clavulanic acid, ampicillin, chloramphenicol, gentamicin, kanamycin, tetracycline, and trimethoprim/sulphamethoxazole. This is the first report of an isolation of salmonellae from a wild bird species from Turkey and the first time S. Enteritidis PT21b has been reported from Turkey.

Animals↗
PubMed2002

From postsynaptic potentials to spikes in the genesis of auditory spatial receptive fields.

Space-specific neurons in the owl's inferior colliculus respond only to a sound coming from a particular direction, which is equivalent to a specific combination of interaural time difference (ITD) and interaural level difference (ILD). Comparison of subthreshold postsynaptic potentials (PSPs) and spike output for the same neurons showed that receptive fields measured in PSPs were much larger than those measured in spikes in both ITD and ILD dimensions. Space-specific neurons fire more spikes for a particular ITD than for its phase equivalents (ITD +/- 1/F, where F is best frequency). This differential response was much less pronounced in PSPs. The two sides of pyramid-shaped ILD curves were more symmetrical in spikes than in PSPs. Furthermore, monaural stimuli that were ineffective in eliciting spikes induced subthreshold PSPs. The main cause of these changes between PSPs and spikes is thresholding. The spiking threshold did not vary with the kind of acoustic stimuli presented. However, the thresholds of sound-induced first spikes were lower than those of later sound-induced and spontaneous spikes. This change in threshold may account for the sharpening of ITD selectivity during the stimulus. Large changes in receptive fields across single neurons are not unique to the owl's space-specific neurons but occur in mammalian visual and somatosensory cortices, suggesting the existence of general principles in the formation of receptive fields in high-order neurons.

Animals↗
PubMed1999

Early visual experience shapes the representation of auditory space in the forebrain gaze fields of the barn owl.

Auditory spatial information is processed in parallel forebrain and midbrain pathways. Sensory experience early in life has been shown to exert a powerful influence on the representation of auditory space in the midbrain space-processing pathway. The goal of this study was to determine whether early experience also shapes the representation of auditory space in the forebrain. Owls were raised wearing prismatic spectacles that shifted the visual field in the horizontal plane. This manipulation altered the relationship between interaural time differences (ITDs), the principal cue used for azimuthal localization, and locations of auditory stimuli in the visual field. Extracellular recordings were used to characterize ITD tuning in the auditory archistriatum (AAr), a subdivision of the forebrain gaze fields, in normal and prism-reared owls. Prism rearing altered the representation of ITD in the AAr. In prism-reared owls, unit tuning for ITD was shifted in the adaptive direction, according to the direction of the optical displacement imposed by the spectacles. Changes in ITD tuning involved the acquisition of unit responses to adaptive ITD values and, to a lesser extent, the elimination of responses to nonadaptive (previously normal) ITD values. Shifts in ITD tuning in the AAr were similar to shifts in ITD tuning observed in the optic tectum of the same owls. This experience-based adjustment of binaural tuning in the AAr helps to maintain mutual registry between the forebrain and midbrain representations of auditory space and may help to ensure consistent behavioral responses to auditory stimuli.

Adaptation, Physiological↗
PubMed1999

Trichinella pseudospiralis in sedentary night-birds of prey from Central Italy.

Trichinella pseudospiralis has been isolated from carnivorous and carrion-feeding mammals and birds in Eastern Europe, Asia, Australia, and North America, suggesting its cosmopolitan distribution. We conducted a survey to detect this parasite in raptorial and carrion-feeding birds in Italy, examining muscles from 205 animals by artificial digestion. We isolated from the breast muscle 1 larva from a tawny owl (Strix aluco) and 2 larvae from a little owl (Athene noctua). These larvae were identified as T. pseudospiralis by the polymerase chain reaction with a specific primer set. This is the first documented report of T. pseudospiralis in animals in Western Europe.

Animals↗