Organochlorine insecticide problems in livestock

1. Antidotal therapy for acute OC intoxications is symptomatic and supportive. Use sedatives to control convulsions and AC to adsorb any pesticide remaining in the gut, and wash topical exposures. 2. Published kinetics should be applied to field situations with caution. In general, residues decline relatively quickly immediately following the last exposure; thereafter, the rate slows considerably. The elimination-rate constant and, hence, the half-life of any given OC is dependent on many variables that usually are not known under field conditions. This fact may result in serious errors if literature values are relied on too heavily in predicting the outcome of "natural" contamination. As a rule of thumb, elimination data derived from animals experimentally fed to plateau concentrations may be regarded as fairly conservative for such purposes, if the contaminated animals are maintained in a normal fashion. Probably the least risky method of predicting return to marketability is using frequent samples, taken at regular intervals (for example, 1 to 2 weeks) during the first month after last exposure, to adjust literature values. 3. Residues from larger dosages and shorter exposures tend to be smaller in proportion to dose and are eliminated more quickly than those resulting from longer exposures and smaller doses. 4. Activated charcoal is of universal benefit only if given immediately after exposure. 5. Pharmaceutical modifiers of xenobiotic metabolism such as phenobarbital are of very limited value. The particular type and amount of residual OC and the potential economic benefit of therapy should be considered thoroughly before undertaking such therapy. In most cases, the expense won't be justified. 6. Mineral oil increases the fecal excretion of some OC. Fecal excretion, however, is so small in relation to total body burdens that even a several-fold increase may not be useful economically except when residue concentrations are low to start with. 7. Nutritional strategies have the advantage of being very cheap. Practitioners should remember, however, that tissue concentrations actually may increase as body fat decreases. The costs of maintaining animals for an extra 6 to 10 months should be considered before undertaking such an effort.(ABSTRACT TRUNCATED AT 400 WORDS)     

Support services for students and faculty

Distance learning is hardly a recent phenomenon. The recent growth of distance-education courses and programs, particularly those offered online, has been dramatic. Students enrolled in distance-education courses deserve the same quality and type of services that students taking courses on campus receive. The same is true of faculty teaching distance courses. Developing strong support services for both groups is an evolutionary process. This article discusses support services for both students and faculty involved in the rapidly expanding online distance-education landscape. Models for providing support to students and faculty are described, the development of these services is explained, and examples of support services are provided.     

Implications of future climate- and land-change scenarios on grassland bird abundance and biodiversity in the Upper Missouri River Basin

Landscape Ecology - Over the past decades, numerous threats from climate- and land-use change to ecosystems have been identified. Grassland ecosystems are among the most endangered in the world and...     

The Gastrointestinal Microbiome: A Review

The gastrointestinal microbiome is a diverse consortium of bacteria, archaea, fungi, protozoa, and viruses that inhabit the gut of all mammals. Studies in humans and other mammals have implicated the microbiome in a range of physiologic processes that are vital to host health including energy homeostasis, metabolism, gut epithelial health, immunologic activity, and neurobehavioral development. The microbial genome confers metabolic capabilities exceeding those of the host organism alone, making the gut microbiome an active participant in host physiology. Recent advances in DNA sequencing technology and computational biology have revolutionized the field of microbiomics, permitting mechanistic evaluation of the relationships between an animal and its microbial symbionts. Changes in the gastrointestinal microbiome are associated with diseases in humans and animals including inflammatory bowel disease, asthma, obesity, metabolic syndrome, cardiovascular disease, immune‐mediated conditions, and neurodevelopmental conditions such as autism spectrum disorder. While there remains a paucity of data regarding the intestinal microbiome in small animals, recent studies have helped to characterize its role in host animal health and associated disease states. This review is intended to familiarize small animal veterinarians with recent advances in the field of microbiomics and to prime them for a future in which diagnostic tests and therapies will incorporate these developments into clinical practice.     

The hemodynamic effects of medetomidine continuous rate infusions in the dog

ObjectiveTo characterize the hemodynamic effects of continuous rate infusions (CRI) of medetomidine administered at doses ranging from 0 to 3 μg kg^?1 hour^?1.Study designProspective, blinded, randomized experimental trial.AnimalsSix adult purpose-bred mongrel dogs.MethodsAnesthesia was induced with sevoflurane for placement of arterial and venous catheters. Dogs recovered from anesthesia after which baseline hemodynamic measurements were obtained via lithium dilution cardiac output (CO) determination, with subsequent measurements via pulse power analysis to provide continuous CO determinations. Medetomidine, 1, 2, or 3 μg kg^?1 hour^?1 or a volume equivalent placebo, was administered via CRI for 60 minutes. Systolic, mean, and diastolic arterial pressure, heart rate (HR), CO and stroke volume were measured and stroke index (SI), cardiac index (CI), total peripheral resistance (TPR), and total peripheral resistance index (TPRI) were calculated at 3, 7, 10, 20, 30, 45, 60, 90, and 120 minutes from the start of the infusion.ResultsIncrease in dose decreased SI by 25%, 19%, and 30%, HR by 33%, 57%, and 60%, CI by 50%, 65%, 70% and increased TPRI by 109%, 235%, and 222% from baseline to the 60-minute measurement for the 1, 2, and 3 μg kg^?1 hour^?1 doses, respectively. HR, TPRI, and CI all showed significant differences over the duration of the study from the placebo treatment.ConclusionsMedetomidine CRI produces clinically relevant changes in CO, TPR, and HR. The demonstrated decrease in CO is largely because of bradycardia and the degree of cardiovascular depression appears to be dose-dependent. These findings are consistent with previously described hemodynamic changes with single bolus administration of medetomidine.Clinical relevanceLow-dose medetomidine CRIs produce clinically relevant hemodynamic depression at doses as low as 1 μg kg^?1 hour^?1 and should be used cautiously in dogs.     

Tachypnea and Antipyresis in Febrile Horses after Sedation with α2‐Agonists

Background: Signs of tachypnea after sedation of febrile horses with α₂‐agonists have been noted previously but have not been further investigated. Objectives: To examine the effects of xylazine and detomidine on respiratory rate and rectal temperature in febrile horses and to investigate if either drug would be less likely than the other to cause changes in these variables. Animals: Nine febrile horses and 9 healthy horses were included in the study. Methods: Horses were randomly assigned to sedation with xylazine 0.5 mg/kg or detomidine 0.01 mg/kg. Heart rate and respiratory rate were recorded before sedation and at 1, 3, and 5 minutes after injection. Hourly measurements of rectal temperature were performed starting before sedation. Results: All febrile horses experienced an episode of tachypnea and antipyresis after sedation. Rectal temperature in the febrile group was significantly lower at 1, 2, and 3 hours after sedation. In several measurements, the decrease was >1°C. Respiratory rate in the febrile group was significantly increased after sedation. All febrile horses were breathing >40 breaths/min and 3 horses >100 breaths/min 5 minutes after sedation. No differences were noted between the 2 treatments. No significant changes in respiratory rate or temperature were noted in the reference group. Conclusions and Clinical Importance: Febrile horses can become tachypneic after sedation with detomidine or xylazine. The antipyretic properties of α₂‐agonists need consideration when evaluating patients that have been sedated several hours before examination.     

Fish protein substrates can substitute effectively for poultry by-product meal when incorporated in high-quality senior dog diets

An experiment was conducted to analytically define several novel fish substrates and determine the effects of feeding diets containing these substrates on total tract nutrient digestibilities and on immune status of senior dogs. The control diet contained poultry by-product meal while test diets contained 20% milt meal (MM), pink salmon hydrolysate (PSH) and white fish meal (WFM) added at the expense of poultry by-product meal. Concentrations of lymphocytes positive for CD3, CD4, CD8 and CD21 cell-surface markers and immunoglobulin concentrations were measured. Gene expression of cytokines tumour necrosis factor (TNF)-, interleukin (IL)-6, interferon (IFN)-, IL-10 and transforming growth factor (TGF)-β was determined by quantitative real-time polymerase chain reaction. Major compositional differences were noted among fish substrates but apparent nutrient digestibility coefficients and immune indices were not affected by treatment. Fish protein substrates were found to be effective substitutes for poultry by-product meal, providing diets of high nutritive value for senior dogs.     

Metribuzin metabolism in tomato: Isolation and identification of N-glucoside conjugates

Metribuzin [4-amino-6-tert-butyl-3-(methylthio)-1,2,4-triazin-5(4H)-one] metabolism was studied in tomato (Lycopersicon esculentum Mill. “Sheyenne”). Pulse-treatment studies with seedlings and excised leaves showed that [5-¹⁴C]metribuzin was rapidly absorbed, translocated (acropetal), and metabolized to more polar products. Foliar tissues of 19-day-old seedlings metabolized 96% of the root-absorbed [¹⁴C]metribuzin in 120 hr. Excised mature leaves metabolized 85–90% of the petiole-absorbed [¹⁴C]metrubuzin in 48 hr. Polar metabolites were isolated by solvent partitioning, and purified by adsorption, thin-layer, and high-performance liquid chromatography. A minor intermediate metabolite (I) was identified as the polar β-d-(N-glucoside) conjugate of metribuzin. The biosynthesis of (I) was demonstrated with a partially purified UDP-glucose: metribuzin N-glucosyltransferase from tomato leaves. A possible correlation between foliar UDP-glucose: metribuzin N-glucosyltransferase activity levels and differences in the tolerance of selected tomato seedling cultivars to metribuzin was suggested. The major polar metabolite (II) was identified as the malonyl β-d-(N-glucoside) conjugate of metribuzin.     

The lipid compositions of two isolates of Cladosporium cucumerinum do not explain their differences in sensitivity to fungicides which inhibit sterol biosynthesis

Isolate 840905 of Cladosporium cucumerinum, when grown on agar or in liqiud medium, was sensitive to triadimenol, HWG 1608 (tebuconazole), fenpropimorph and pimaricin but relatively resistant to terbinafine. Conversely, isolate 49628 was sensitive to terbinafine but relatively resistant to the other fungicides. Changes in sterol composition following treatment with the fungicides reflected the known modes of action of each fungicide. When individual enantiomers of triadimenol were tested against isolate 840905 the order of activity in reducing mycelial growth was 1 S, 2R > 1R, 2R > 1R, 2S ≈? 1S, 2S, and this was paralleled by the depletion of ergosterol and the appearance of 14α-methyl sterols. Isolate 49628 had a greater saturated:unsaturated fatty acid ratio than did isolate 840905 but no major changes in fatty acid composition of either isolate were induced by fungicide treatment. There appears to be no obvious explanation for the differences in fungicide sensitivity of the isolates in terms of their lipid compositions.     

Fruit and vegetable fiber fermentation by gut microflora from canines

The objective of this study was to assess fermentability by canine gut microflora to include shortchain fatty acid (SCFA) production, organic matter (OM) disappearance, and gas production of vegetable and fruit fiber sources compared to fiber standards (psyllium, citrus pectin, and Solka Floc). Fiber sources included apple pomace, carrot pomace, flaxseed, fruit blend (mixture of peach, almond, nectarine, and plum), grape pomace, pea hulls, pistachio, and tomato pomace. Substrates were fermented in vitro for 4, 12, and 24 h with fecal flora obtained from three healthy dogs. Citrus pectin had the highest OM disappearance, SCFA production, and gas production at all times of fermentation; psyllium was intermediate and Solka Floc was lowest. A wide variation in fermentability was noted among the vegetable and fruit fiber sources. Apple pomace, carrot pomace, and flaxseed had the greatest fermentability as assessed by OM disappearance. Pea hulls and tomato pomace had intermediate OM disappearances, and fruit blend, grape pomace, and pistachio were poorly fermented. Carrot pomace produced the largest amounts of gas and SCFA. Apple pomace produced high concentrations of gas but intermediate concentrations of SCFA. Pea hulls and tomato pomace produced intermediate concentrations of gas and SCFA, whereas flaxseed, fruit blend, grape pomace, and pistachio produced low amounts of these fermentation products. For all substrates collectively, OM disappearance was highly correlated with both gas production (r2 = 0.782 and 0.723 for 12- and 24-h values, respectively) and SCFA production (r2 = 0.737 and 0.738 for 12- and 24-h values, respectively). In general, OM disappearance, gas production, and SCFA production were related to the insoluble:soluble fiber ratio in the samples; as the insoluble:soluble ratio decreased (increased soluble fiber), the OM disappearance, gas production, and SCFA production increased.