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Dexamethasone is approved for cattle in Canada for several conditions, but no withdrawal times are currently provided on the approved labels. Recently, the list of Maximum Residues Limits for Veterinary Drugs in Foods in Canada was amended to include dexamethasone. The objectives of this study were to determine the residue depletion profile of dexamethasone after an extra‐label dosage regimen in milk of healthy lactating dairy cattle (n = 18) and in edible tissues of healthy beef cattle (n = 16) and to suggest withdrawal intervals. Dexamethasone was administered intramuscularly at 0.05 mg/kg daily for 3 days. Milk samples were collected prior to treatment and every 12 h up to 96 h post‐dose. Muscle, liver, kidney, and peri‐renal fat tissues were collected from beef cattle at 3, 7, 11, or 15 days post‐dose. Dexamethasone analysis was performed by liquid chromatography/mass spectrophotometry. Dexamethasone residues were detected in milk samples up to 36 h. Muscle and fat had no detectable dexamethasone residues while kidney and liver had detectable residues only on day 3 post‐dose. A withdrawal interval of 48 h for milk in Canadian dairy cattle and 7 days for meat in Canadian beef cattle are suggested for the dexamethasone treatment regimen most commonly requested to CgFARAD™. [ABSTRACT FROM AUTHOR]

Trazodone and gabapentin are common oral sedatives in cats, used alone or combined, but no pharmacokinetic studies exist for trazodone in this species. The objective of this study was to determine the pharmacokinetics of oral trazodone (T) alone, or in combination with gabapentin (G) in healthy cats. Cats (n = 6) were randomly allocated to receive T (3 mg/kg) intravenously (IV), T (5 mg/kg) orally (PO), or T (5 mg/kg) and G (10 mg/kg) PO with a 1‐week washout period between treatments. Heart rate, respiratory rate, indirect blood pressure, and level of sedation were assessed, and venous blood samples were collected serially over 24 h. Analysis of plasma trazodone concentration was performed using liquid chromatography–tandem mass spectrometry (LC–MS/MS). Oral T administration resulted in a bioavailability of 54.9(7–96)%, and 17.2(11–25)% when administered with G. Tmax 0.17 (0.17–0.5) and 0.17 (0.17–0.75) h; Cmax 1.67 ± 0.91 and 1.22 ± 0.54 μg/mL, AUC 5.23 (2.0–18.76) and 2.37 (1.17–7.80) h*μg/mL; T1/2 5.12 ± 2.56 and 4.71 ± 1.07 h; for T and TG, respectively. Sedation was significant when compared to baseline in all groups from 20 or 45 min to 8 h indicating some lag between peak plasma concentration and sedative effects. Physiological variables remained within normal limits. This study concludes that oral trazodone is rapidly absorbed in healthy cats. Addition of gabapentin did not result in more profound sedation, showing no clinical advantage of combining these drugs in this study population. [ABSTRACT FROM AUTHOR]

The objectives of this study were to investigate the pharmacokinetics (PK), pharmacodynamics (PD), and the efficacy of oral administration of doxycycline (DXC) in horses with Streptococcus zooepidemicus tissue infections. Tissue chambers (TC) were implanted subcutaneously in the cervical region of 7 horses and inoculated with a single S. zooepidemicus isolate with a minimum inhibitory concentration (MIC) of 0.25 µg/ml, determined by agar dilution. Doxycycline hyclate (10 mg/kg, orally, q 12 h, for 5 days) mixed with poloxamer gel was started following inoculation. The TC fluid was sampled prior to and following inoculation for cytology analysis, quantitative culture, and DXC determination. Plasma DXC concentrations were measured over 48 h following the last dose of DXC administered. The mean plasma peak concentration (Cmax) of DXC was 0.32 µg/ml, and concentrations above the MIC were only reached in 3 TC samples. In plasma, mean T > MIC was 2.4 h, mean Cmax/MIC was 1.30, and mean AUClast/MIC was 11.63 h. These PK/PD indices did not reach the suggested targets for DXC treatments of infections, and the TC abscessed in all horses. This is the first study to evaluate the recommended dose of DXC in horse in an infection model. [ABSTRACT FROM AUTHOR]

The tumor suppressor protein p53 limits mutagenesis in response to ultraviolet‐B (UVB) light exposure by activating the transcription of genes that mitigate the damaging effects of UVB radiation on DNA. Because most nonmelanoma skin cancers (NMSCs) occur in older individuals, it is important to understand the process of mutagenesis in the geriatric skin microenvironment. Based on previous studies demonstrating that geriatric skin expresses lower levels of the growth factor insulin‐like growth factor‐1 (IGF‐1) than young adult skin, a role for IGF‐1 in the regulation of p53 target genes was investigated in both human keratinocytes in vitro and human skin explants ex vivo. The products of the p53 target genes p21 and DNA polymerase eta (pol η) were found to be increased by UVB exposure in both experimental systems, and this induction was observed to be partially abrogated by depriving keratinocytes of IGF‐1 in vitro or by the treatment of keratinocytes in vitro and human skin explants with an IGF‐1 receptor antagonist. Because p21 and pol η function to limit mutagenic DNA replication following UVB exposure, these results suggest that NMSC risk in geriatric populations may be due to age‐dependent decreases in IGF‐1 signaling that disrupt p53 function in the skin. [ABSTRACT FROM AUTHOR]

This study was designed to investigate the pharmacokinetics of imidocarb, a carbanilide derivative, in white‐tailed deer (Odocoileus virginianus). The pharmacokinetic properties of a single intramuscular (IM) dose of imidocarb were determined in 10 deer. A single IM injection of 3.0 mg/kg imidocarb dipropionate was administered, and blood samples were collected prior to, and up to 48 hr after imidocarb administration. Plasma imidocarb concentrations were determined by high‐performance liquid chromatography with ultraviolet detection. The disposition of plasma imidocarb was best characterized by a two‐compartment open model. The mean ± SE maximal imidocarb concentration in deer was 880.78 ± 81.12 ng/ml at 38.63 ± 5.30 min postinjection. The distribution phase had a half‐life (t1/2α) of 25.90 ± 10.21 min, and plasma imidocarb concentration declined with a terminal elimination half‐life (t1/2β) of 464.06 ± 104.08 min (7.73 ± 1.73 hr). Apparent volume of distribution based on the terminal phase (VZ/F) was 9.20 ± 2.70 L/kg, and apparent total body clearance (Cl/F) was 15.97 ± 1.28 ml min−1 kg−1. [ABSTRACT FROM AUTHOR]

Midazolam is a benzodiazepine with sedative, muscle relaxant, anxiolytic, and anticonvulsant effects. Twelve ball pythons (Python regius) were used in a parallel study evaluating the pharmacokinetics of 1 mg/kg midazolam following a single intracardiac (IC) or intramuscular (IM) administration. Blood was collected from a central venous catheter placed 7 days prior, or by cardiocentesis, at 15 time points starting just prior to and up to 72 hr after drug administration. Plasma concentrations of midazolam and 1‐hydroxymidazolam were determined by the use of high‐performance liquid chromatography tandem‐mass spectrometry and pharmacokinetic parameters were estimated using noncompartmental analysis. The mean ± SD terminal half‐lives of IC and IM midazolam were 12.04 ± 3.25 hr and 16.54 ± 7.10 hr, respectively. The area under the concentration‐time curve extrapolated to infinity, clearance, and apparent volume of distribution in steady‐state of IC midazolam were 19,112.3 ± 3,095.9 ng*hr/ml, 0.053 ± 0.008 L hr−1 kg−1, and 0.865 ± 0.289 L/kg, respectively. The bioavailability of IM midazolam was estimated at 89%. Maximum plasma concentrations following an IM administration were reached 2.33 ± 0.98 hr and 24.00 ± 14.12 hr postinjection for midazolam and 1‐hydroxymidazolam, respectively, and 22.33 ± 20.26 hr postinjection for 1‐hydroxymidazolam following IC administration. [ABSTRACT FROM AUTHOR]

Abstract: Marine finfish require long‐chain (LC) polyunsaturated fatty acids (PUFAs) for normal physiological function, and because these LC‐PUFAs cannot be synthesized by the fish, they must be obtained from the diet. Three LC‐PUFAs—arachidonic acid (ARA; 20:4[n‐6]), eicosapentaenoic acid (EPA; 20:5[n‐3]), and docosahexaenoic acid (22:6[n‐3])—are especially important for growth and development of marine fish embryos and larvae. We supplemented ARA in the diet of Yellowtail Seriola dorsalis to determine whether ARA levels have an effect on egg and larval quality. Two experimental diets were offered to replicate groups of Yellowtail held in 10‐m3 tanks under ambient water temperature and photoperiod conditions. The reference diet (REF‐D; 1.4 g of ARA per 100 g of total fatty acids) was a commercial premix (BioVita Starter Mash; Bio‐Oregon) without ARA supplementation; the ARA diet (ARA‐D; 4.7 g/100 g total fatty acids) was the commercial premix with 1.0% concentrated ARA oil (40% ARA, weight/weight) added. Fish in the REF‐D treatment spawned 53 times during the spawning season for a total of 18.0 million eggs. Fish in the ARA‐D treatment tanks spawned 30 times during the spawning season for a total of 13.0 million eggs. Viability, hatch rates, and egg diameter were all significantly higher in the ARA‐D treatment. Fatty acid analysis of the diets showed a significant increase in ARA in the ARA‐D diet, and that same increase was seen in the resulting eggs. Correspondingly, ARA‐D eggs had a lower EPA : ARA ratio than REF‐D eggs. The supplementation of ARA generated increases in key performance indices, which might have biological significance in a production setting. We additionally demonstrated that Yellowtail will spawn without hormone induction in small (10‐m3) breeding tanks, which facilitates manipulative studies of broodstock nutrition as reported here. These data represent an excellent starting point for dietary refinements in the future. [ABSTRACT FROM AUTHOR]

When organisms with similar phenotypes have conflicting management and conservation initiatives, approaches are needed to differentiate among subpopulations or discrete groups. For example, the eastern metapopulation of the double-crested cormorant ( Phalacrocorax auritus) has a migratory phenotype that is culled because they are viewed as a threat to commercial and natural resources, whereas resident birds are targeted for conservation. Understanding the distinct breeding habitats of resident versus migratory cormorants would aid in identification and management decisions. Here, we use species distribution models ( SDM: Maxent) of cormorant nesting habitat to examine the eastern P. auritus metapopulation and the predicted breeding sites of its phenotypes. We then estimate the phenotypic identity of breeding colonies of cormorants where management plans are being developed. We transferred SDMs trained on data from resident bird colonies in Florida and migratory bird colonies in Minnesota to South Carolina in an effort to identify the phenotype of breeding cormorants there based on the local landscape characteristics. Nesting habitat characteristics of cormorant colonies in South Carolina more closely resembled those of the Florida phenotype than those of birds of the Minnesota phenotype. The presence of the resident phenotype in summer suggests that migratory and resident cormorants will co-occur in South Carolina in winter. Thus, there is an opportunity for separate management strategies for the two phenotypes in that state. We found differences in nesting habitat characteristics that could be used to refine management strategies and reduce human conflicts with abundant winter migrants and, at the same time, conserve less common colonies of resident cormorants. The models we use here show potential for advancing the study of geographically overlapping phenotypes with differing conservation and management priorities. [ABSTRACT FROM AUTHOR]

Phenylbutazone (PBZ) is permitted to be used for the treatment of musculoskeletal pain and inflammation in race horses but it is not approved for use in horses destined for human consumption. In a recent study initiated in our laboratory to study the disposition of PBZ and its oxyphenbutazone (OXPBZ) metabolite in equine tissues, we compared the effect of an additional enzymatic hydrolysis step with ß-glucuronidase on the results of the analysis for PBZ without enzymatic hydrolysis. Incurred tissue samples obtained from a female horse dosed with PBZ at 8.8 mg/kg for 3 days and sacrificed 6 days following the last administration were used for this study. Liver, kidney, and muscle tissues were collected, extracted, cleaned up on a silica-based solid-phase extraction (SPE) preceded by a weak-anion exchange SPE and analyzed with our in-house validated liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for PBZ and OXPBZ. Addition of the hydrolysis step resulted in a significant increase in recovery of both PBZ and OXPBZ residues. © 2016 Her Majesty the Queen in Right of Canada. Drug Testing and Analysis © 2016 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Objective - To compare the recovery times, recovery quality, and cardiovascular (CV) effects of 3 anesthetic protocols during 24 hours of mechanical ventilation (MV) in healthy cats. Design - Prospective, randomized, crossover study. Setting - Research laboratory at a veterinary teaching hospital. Animals - Six healthy intact male purpose-bred cats. Interventions - Each cat was randomly assigned to receive 3 anesthetic protocols for 24 hours of MV; Protocol K consisted of ketamine, Protocol P, propofol; and Protocol PK, propofol plus fixed-rate low-dose ketamine. Each infusion drug dose was adjusted using a sedation scoring system. All protocols included fixed doses of fentanyl (10 μg/kg/h) and midazolam (0.5 mg/kg/h). Measurements and Main Results - Drug doses and recovery times were recorded. Recovery quality was scored. Blood gas results, CV parameters, and frequency of bradycardia or hypotension requiring interventions were recorded. The mean d dose ± standard error of K was 81.3 ± 3.3 μg/kg/m. The median dose (95% cardiac index) of propofol (μg/kg/m) in PK was 16.0 (13.1, 19.6) and in P was 48.1 (39.3, 58.9). P necessitated significantly more propofol than PK (P<0.05). Protocol K (35.6±3.2 hours) had significantly longer times to full recovery compared to P (18.2 ± 3.2 hours). Protocol K had significantly longer times to head up, crawling, and standing compared to P and PK. Cats sedated with PK (2.33 ± 0.47) required significantly more interventions for hypotension than K (0.50 ± 0.47). Protocol P (3.2 ± 0.4) and PK (1.4 ± 0.3) required significantly more interventions for bradycardia compared to K (0.8 ± 0.3). When comparing protocol K to P and PK, significant differences in blood pressure, lactate, oxygen delivery, and oxygen consumption were noted. Conclusions - Cats anesthetized with P had shorter times to full recovery compared to K. Cats anesthetized with K required fewer interventions for bradycardia or hypotension but had longer recovery times compared to P or PK. Protocol PK reduced the propofol dose required to maintain optimal anesthesia. [ABSTRACT FROM AUTHOR]

To better understand bird response to percentage and pattern of woody cover in agricultural areas, we recorded richness and abundance of breeding birds in 500-m transects along 18 wooded streams in southeastern Nebraska. Transects had differing amounts of woody cover in the surrounding landscape (∼2-39%) out to distances of 500, 1,000, and 2,000 m. We grouped bird species as woodland (22 species) or edge (30 species) and analyzed results from the 1999 and 2000 breeding seasons using information theoretic methods. Richness of the woodland group increased with percentage of woody cover out to 500 m, but abundance did not change. In contrast, richness of the edge group was not affected by landscape variables, but abundance increased as percentage of woody cover decreased out to 1,000 m. Eight species increased in abundance and 5 decreased with increasing percentage of woody cover in the landscape out to distances of 500, 1,000, or 2,000 m. The great crested flycatcher (Myiarchus crinitus) was not present at sites with ≤14.7% woody cover in the surrounding landscape out to 500 m, and the eastern wood-pewee (Contopus virens), except for one site, was not present at sites with ≤24% woody cover out to 500 m. The Baltimore oriole (Icterus galbula) and warbling vireo (Vireo gilvus) apparently responded to the presence of large eastern cottonwood (Populus deltoides) trees. Management for a diverse avifauna in fragmented agricultural landscapes should include both local- and landscape-scale variables, including the amount and pattern of woody cover in the surrounding landscape. [ABSTRACT FROM AUTHOR]

Ecological relationships between wildlife conservation and farm management provide common ground for the enhancement of bird habitat and the natural suppression of pests on farmland. We compared bird populations in 15 paired organic and nonorganic sites (cornfields plus edges, 30 sites total) that were similar in environment and edge habitat but that differed in use of fertilizers, herbicides, cultivation, and crop rotations. At each site, we used one strip transect to sample birds and vegetation in the bordering edge and cornfield perimeter (0–25 m from the edge) and another to sample in the cornfield (50–150 m from the edge). During the 1995 and 1996 growing seasons, we recorded 54 bird species, 51 in organic and 39 in nonorganic sites. On average, bird abundance on organic sites was 2.6 times higher than on nonorganic sites, and mean species richness per visit was 2.0 times greater. When analyzed separately, organic edge, perimeter, and field transects supported higher bird abundance and greater richness than did their nonorganic counterparts. Abundance and richness were higher on organic sites for insectivores, omnivores, and granivores, and for each of three migratory groups. Twelve species were individually more abundant on organic sites, and one regularly observed species was observed only on organic sites. No species had greater abundance on nonorganic sites. More non-crop vegetation on organic cornfields, most likely a result of no herbicide use, may have provided better foraging opportunities for birds. The plant food, cover, and invertebrate prey in organic cornfields appeared to augment birds not only in the field but also in the uncropped edges. Organic fields appear to benefit birds, but reproductive success needs further study. Modifying farm-management practices, especially near field edges where bird activity is concentrated, may enhance the conservation of birds and their potential predation on crop pests. [ABSTRACT FROM AUTHOR]

World cities attract two major streams of migrants -- those who occupy the upper levels of their occupational hierarchies (the 'globalized professionals') on the one hand and marginalized, low-skill workers on the other. These two groups are often of different ethnic status, and it is argued that multicultural world cities are thus fractured in both their labour and housing markets along ethnic as well as economic lines. There has been little formal testing of these ideas, however. In this introductory article we introduce a method that can be used for comparative studies of residential fragmentation -- an index of residential concentration -- and apply it to three cities which have experienced rapid, multiethnic immigration in recent decades (New York, Sydney and Auckland). The patterns displayed indicate much greater fragmentation in New York than in the other two cities, suggesting that the 'conventional wisdom' regarding ethnic residential patterns may over-emphasize 'American exceptionalism'. [ABSTRACT FROM AUTHOR]

Presents information on a study which evaluated bird use of rural and urban converted railroad rights-of-way in southeast Nebraska. Survey of birds from 1992 to 1994; Methodology of the study; Results and discussion; Conclusions.