Microbiological and histopathological findings in cases of fatal bovine respiratory disease of feedlot cattle in Western Canada

The aim of this study was to describe the microbiologic agents and pathologic processes in fatal bovine respiratory disease (BRD) of feedlot cattle and to investigate associations between agents and pathologic processes. Ninety feedlot calves diagnosed at necropsy with BRD and 9 control calves without BRD were examined, using immunohistochemical (IHC) staining and histopathologic studies. Mannheimia haemolytica (MH) (peracute, acute, and subacute cases) and Mycoplasma bovis (MB) (subacute, bronchiolar, and chronic cases) were the most common agents identified in fatal BRD cases. Significant associations (P < 0.10) were detected between microbiologic agents and between agents and pathologic processes. When IHC staining was used, 25/26 (96%) of animals that were positive for bovine viral diarrhea virus (BVDV) were also positive for MH; 12/15 (80 %) of animals that were positive for Histophilus somni (HS) were also positive for MB; and all of the animals that were positive for HS were negative for MH and BVDV. This quantitative pathological study demonstrates that several etiologic agents and pathologic processes are involved in fatal BRD of feedlot cattle.     

Endemic Visceral Leishmaniasis in a Dog from Texas

Visceral leishmaniasis was diagnosed by cytology and positive indirect immunofluorescent antibody titers to Leishmania donovani in a 7-month-old female Basenji dog from Texas. Clinical and laboratory findings included weight loss, hematochezia, hyperglobulinemia, hypoalbuminemia, anemia, and neutrophilic leukocytosis. Evidence of response to treatment with diminazene aceturate and ketoconazole included improvement in the abnormal clinical, hematologic, and biochemical findings, decreased serum globulin concentration and antibody titer to Leishmania donovani, and absence of organisms in examined tissues. Several foci of endemic leishmaniasis have been reported in the United States. Because of its zoonotic potential and the lack of approved treatments for dogs with leishmaniasis in the United States, the development of effective treatment strategies is needed.     

Halicephalobus gingivalis-associated meningoencephalitis in a Thoroughbred foal.

A 13-week-old Thoroughbred colt from central Kentucky was euthanized after an acute onset of ataxia, blindness, head tremors, leaning to the right, recumbency, and seizures. Microscopically, there was a verminous meningoencephalitis characterized by an eosinophilic and granulomatous inflammatory reaction primarily affecting the cerebellum. Dispersed within regions of inflammation were numerous cross and longitudinal sections of intact and degenerative small nematodes. The nematodes had dorsoflexed ovaries and ventroflexed vulvas, which are distinguishing features of Halicephalobus gingivalis. Intact nematodes, compatible with H. gingivalis, also were recovered and identified from portions of the brain that had been frozen for 5-week post-necropsy examination via tissue maceration and additional laboratory techniques.     

Soybean shoot metabolism of isopropyl-3-chlorocarbanilate: Ortho and para aryl hydroxylation

This laboratory reported that isopropyl-3-chlorocarbanilate-phenyl-U-¹⁴C (chlorpropham-phenyl-¹⁴C) was absorbed, translocated, and metabolized by soybean plants. Both polar metabolites and insoluble residues were found in roots, whereas only polar metabolites were found in shoot tissues. In both roots and shoots the polar metabolites were shown to be the O-glucoside of isopropyl-2-hydroxy-5-chlorocarbanilate (2-hydroxy-chlorpropham). In shoot tissue there were other polar metabolites that were not identified. The experiments with soybeans have been repeated, but with new isolation and purification procedures. The plants were root treated with both chlorpropham-phenyl-¹⁴C and isopropyl-3-chlorocarbanilate-2-isopropyl-¹⁴C. The roots and shoots were extracted and separated into the polar, nonpolar, and insoluble metabolic components, using the Bligh-Dyer extraction method. The polar metabolites were separated by gel permeation chromatography. Further purification was accomplished on Amberlite XAD-2. The polar metabolites from the shoot and root tissues were hydrolyzed either by β-glucosidase or hesperidinase. The enzyme liberated aglycones were derivatized and separated by gas-liquid chromatography, and the components were characterized by mass spectrometry or NMR. The results of this study showed that the polar metabolites of soybean shoots were 2-hydroxy-chlorpropham and isopropyl-4-hydroxy-3-chlorocarbanilate (4-hydroxy-chlorpropham). These two hydroxy-chlorpropham metabolites were found in soybean shoots at a ratio of approximately 1:1. The only aglycone found in root tissue was 2-hydroxy-chlorpropham. Using the new procedures, no evidence was obtained for the presence of the unidentified polar metabolites that were previously observed in shoot tissues.     

Lymphatic metastasis in the absence of functional intratumor lymphatics

Lymphatic metastasis contributes to mortality from solid tumors. Whether metastasizing cancer cells reach lymph nodes via intratumor lymphatic vessels is unknown. Here, we examine functional lymphatics associated with mouse tumors expressing normal or elevated levels of vascular endothelial growth factor-C (VEGF-C), a molecule that stimulates lymphangiogenesis. Although VEGF-C overexpression increased lymphatic surface area in the tumor margin and lymphatic metastasis, these tumors contained no functional lymphatics, as assessed by four independent functional assays and immunohistochemical staining. These findings suggest that the functional lymphatics in the tumor margin alone are sufficient for lymphatic metastasis and should be targeted therapeutically.     

Effect of dietary concentrate content on feed intake,feed efficiency,and meat quality of Holstein steers fattened in a hot environment

The objective of this study was to investigate the effect of feeding high and low concentrate diets on feed intake and feed efficiency, the morphological characteristics of the rumen papillae, and meat quality of Holstein steers fattened under hot climate conditions in Oman. Ten male Holstein calves, of 5 months of age, were selected for the experiment. The animals were fed concentrate and Rhodes grass hay and were divided into two groups of high concentrate (HC, n = 5) and low concentrate diets (LC, n = 5), in which their feed intake, weight gain, and feed efficiency were evaluated across three growing periods. Feed intake and efficiency and average daily gain (ADG) of the HC group were significantly greater than for the LC group and were affected by the diet (p < .01) and the period (p < .001). Across the fattening periods, ADG declined in both groups, with ADG improved by 35% for steers on the HC diet compared to steers on the LC diet. Carcass meat quality was not affected significantly by the dietary concentrate level. In conclusion, our results can be used to make improvements in feed efficiency of Holstein steers under hot climate conditions.     

Combined effects of dexmedetomidine and vatinoxan infusions on minimum alveolar concentration and cardiopulmonary function in sevoflurane-anesthetized dogs

ObjectiveTo evaluate the effects of combined infusions of vatinoxan and dexmedetomidine on inhalant anesthetic requirement and cardiopulmonary function in dogs.Study designProspective experimental study.MethodsA total of six Beagle dogs were anesthetized to determine sevoflurane minimum alveolar concentration (MAC) prior to and after an intravenous (IV) dose (loading, then continuous infusion) of dexmedetomidine (4.5 μg kg^–1 hour^–1) and after two IV doses of vatinoxan in sequence (90 and 180 μg kg^–1 hour^–1). Blood was collected for plasma dexmedetomidine and vatinoxan concentrations. During a separate anesthesia, cardiac output (CO) was measured under equivalent MAC conditions of sevoflurane and dexmedetomidine, and then with each added dose of vatinoxan. For each treatment, cardiovascular variables were measured with spontaneous and controlled ventilation. Repeated measures analyses were performed for each response variable; for all analyses, p < 0.05 was considered significant.ResultsDexmedetomidine reduced sevoflurane MAC by 67% (0.64 ± 0.1%), mean ± standard deviation in dogs. The addition of vatinoxan attenuated this to 57% (0.81 ± 0.1%) and 43% (1.1 ± 0.1%) with low and high doses, respectively, and caused a reduction in plasma dexmedetomidine concentrations. Heart rate and CO decreased while systemic vascular resistance increased with dexmedetomidine regardless of ventilation mode. The co-administration of vatinoxan dose-dependently modified these effects such that cardiovascular variables approached baseline.Conclusions and clinical relevanceIV infusions of 90 and 180 μg kg^–1 hour^–1 of vatinoxan combined with 4.5 μg kg^–1 hour^–1 dexmedetomidine provide a meaningful reduction in sevoflurane requirement in dogs. Although sevoflurane MAC-sparing properties of dexmedetomidine in dogs are attenuated by vatinoxan, the cardiovascular function is improved. Doses of vatinoxan >180 μg kg^–1 hour^–1 might improve cardiovascular function further in combination with this dose of dexmedetomidine, but beneficial effects on anesthesia plane and recovery quality may be lost.     

Identification of Fine Particle Sources in Mid-Atlantic US Area

The U.S. Environmental Protection Agency (EPA) designated 20 urban areas including major cities located in mid-Atlantic US area as being in non-attainment of the new national ambient air quality standards for PM_2.5 (particulate matter ≤2.5 μm in aerodynamic diameter). To support the development of effective State Implementation Plans for PM_2.5 in the non-attainment area, 24-h integrated Speciation Trends Networks data collected in the mid-Atlantic US urban area were analyzed through the application of the positive matrix factorization (PMF). A total of 117 to 235 samples and 27 to 29 chemical species collected at the four monitoring sites between 2001 and 2003 were analyzed and six to nine sources were identified. Secondary particles provided the highest contributions to PM_2.5 mass concentrations (38–50% for secondary sulfate; 9–18% for secondary nitrate). Potential source contribution function analyses show the potential source areas and pathways of secondary particles contributing to this region, especially the regional influences of the biogenic as well as anthropogenic secondary particles. Motor vehicle emissions contributed 21–33% to the PM_2.5 mass concentration. In four sites in southern New Jersey and Delaware, gasoline vehicle and diesel emissions were tentatively separated by different abundances of organic and elemental carbons. The compositional profiles for gasoline vehicle and diesel emissions are similar across this area. In addition, other combustion sources, aged sea salt, and intercontinental dust storms were identified.     

Physiologic effects of furosemide in combination with water restriction when administered at 4 and 24 hours prior to high-intensity treadmill training

Although controversial, due to its reported effectiveness in attenuating bleeding associated with exercise-induced pulmonary hemorrhage (EIPH), furosemide is currently a permitted race day medication in most North American racing jurisdictions. The objective of this study was to assess the efficacy of furosemide in reducing the presence and severity of EIPH when administered 24 hr prior to strenuous treadmill exercise. Eight exercised Thoroughbred horses received saline or 250 mg of furosemide either 4 or 24 hr prior to high-speed treadmill exercise in a balanced 3-way cross-over design. Blood samples were collected for determination of furosemide, lactate, hemoglobin, blood gas, and electrolyte concentrations. Heart rate and pulmonary arterial pressure were measured throughout the run and endoscopic examination and bronchoalveolar lavage (BAL) performed. Horses were assigned an EIPH score and the number of red blood cells in BAL fluid determined. Although not significantly different, endoscopic EIPH scores were lower in the 4-hr versus the 24-hr and saline groups. RBC counts were not significantly different between the treatment groups. Pulmonary arterial pressures were significantly increased at higher speeds; however, there were no significant differences between dose groups when controlling for speed. A small sample size and unknown bleeding history warrant a larger-scale study.