Climatic warming and the decline of zooplankton in the california current

Since 1951, the biomass of macrozooplankton in waters off southern California has decreased by 80 percent. During the same period, the surface layer warmed-by more than 1.5 degrees C in some places-and the temperature difference across the thermocline increased. Increased stratification resulted in less lifting of the thermocline by wind-driven upwelling. A shallower source of upwelled waters provided less inorganic nutrient for new biological production and hence supported a smaller zooplankton population. Continued warming could lead to further decline of zooplankton.     

Reduced tongue tone associated with degeneration of the hypoglossal nerve nucleus in a horse with equine motor neuron disease

Equine motor neuron disease (EMND) is a condition characterised by generalised weakness and muscle atrophy associated with degeneration of motor neurons in the ventral horns of the spinal cord. Despite the frequent detection of cranial nerve nuclei pathology during post mortem examination, associated clinical signs are rarely reported. This report describes a case of EMND in a pony gelding that presented with clinical signs of diffuse neuromuscular weakness associated with marked flaccidity of the tongue, making differentiation from similar neuromuscular conditions, particularly botulism, extremely challenging.     

Behavioral and physiological responses to stabling in naive horses

The purpose of this study was to investigate the response of horses to confinement and isolation in a stable (indoor individual housing) for the first time using behavioral indices, heart rate, and salivary cortisol concentration. Six naive 2-year-old Australian Stock Horse fillies were examined at 4-hour intervals over 24 hours in an outdoor group paddock followed by 24 hours in indoor individual housing. Behavioral observations and scores and heart rates were recorded and saliva samples were taken at each interval. During stabling, all horses became agitated and demonstrated increased vocalization and movement. Behavioral scores were significantly higher in the indoor individual housing (P < .001). No significant difference in heart rates between the two environments was detected. Mean salivary cortisol did not increase significantly (2 ng/mL ± 1.4 ng/mL in outdoor group paddock vs 2.5 mL ± 1.2 ng/mL in indoor individual housing). No diurnal rhythm in salivary cortisol was evident in either the outdoor group paddock or indoor individual housing. The results of this study highlight that a combination of behavioral and physiological measures allow better understanding of stress, where one measurement may be misleading. First time stabling of horses elicited marked behavioral responses indicative of stress that were not reflected in increased heart rates or salivary cortisol concentrations. The lack of a diurnal cortisol rhythm and the comparatively high basal cortisol concentrations found in the outdoor group paddock environment may imply that the fillies were already stressed; therefore, stabling did not cause further aberrations detectable by salivary cortisol analysis.     

Coronary band dystrophy in two horses

Two mature large-breed horses with coronary band dystrophy and chorioptic mange are described. They both had clinical signs of coronary band scaling and crusting but were not lame. Coronary band dystrophy can be differentiated from similar clinical conditions on the basis of the histological appearance of skin biopsy specimens, and by the exclusion of other possible disease processes. Its aetiology is uncertain, but probably involves a localised defect of keratinisation affecting the specialised epithelium of the coronary band.     

Male reproductive traits and their relationship to reproductive traits in their female progeny: a systematic review

The overall objective of one of the major research programs in the Co-operative Research Centre (CRC) for Beef Genetic Technologies is to 'Improve female reproductive performance' in tropical, northern Australian beef cattle herds. To address this overall objective, a quantitative genetics project focused on investigation of male reproductive traits was designed and linked to three female reproduction-focussed projects, (i) discovery of genes associated with post-partum re-conception and age at puberty; (ii) expression of genes associated with post-partum re-conception; and (iii) early predictors of lifetime female reproductive performance. During the initial planning of this male reproductive traits project, the CRC Scientific Review Committee recommended that the research team investigate and evaluate potentially new, early-life (i.e able to be measured before 2 years of age) predictors of both male and female reproductive performance. To address this recommendation, the following was carried out: (i) criteria for selection of traditional and candidate traits were established; (ii) methodology for tabulation of potential traits/phenotypes that define male and female reproductive function was developed; and (iii) a systematic scientific review of early-life predictors of male and female fertility was prepared. This review concluded that although factors that might be useful in predicting male reproductive performance have been studied for many years, there was relatively little useful information available to meet the objectives of this review. It was also concluded that the direction of future research should be guided not only by previous research which was scarce, but also by speculative hypotheses arising from an understanding of the physiological, endocrinological and genetic processes active in reproduction. A small number of new traits were recommended in addition to traditional sperm morphology, sexual behaviour, anatomical structure and growth traits. Potential additional traits include measurement of gonadotrophin-releasing hormone-stimulated luteinizing hormone (GnRH-stimulated LH); inhibin; several seminal plasma proteins (osteopontin, spermadhesin and seminal plasma proteins BSP30 and phospholipase A(2) could be used in an index); 11β-hydroxysteriod dehydrogenase; and leptin. In addition, the potential also exists to screen animals for a number of genetic markers associated with age of puberty, follicular recruitment and ovulation rate and genes associated with bovine seminal plasma protein and testosterone production. Insulin-like growth factor-1 (IGF-1) measurements are included because of their association with growth parameters, and an additional analysis demonstrated associations with male and female reproductive traits. Some of these factors have been previously evaluated in small numbers of animals of various species under intensive management conditions. Therefore, there is a need to evaluate these factors in much larger numbers of beef cattle grazing semi-extensive tropical production systems in northern Australia to determine their value in improving beef cattle enterprise profitability through improved herd fertility.     

The prevalence and nature of cardiac arrhythmias in horses following general anaesthesia and surgery

Background

The prevalence and nature of arrhythmias in horses following general anaesthesia and surgery is poorly documented. It has been proposed that horses undergoing emergency surgery for gastrointestinal disorders may be at particular risk of developing arrhythmias. Our primary objective was to determine the prevalence and nature of arrhythmias in horses following anaesthesia in a clinical setting and to establish if there was a difference in the prevalence of arrhythmias between horses with and without gastrointestinal disease undergoing surgery. Our secondary objective was to assess selected available risk factors for association with the development of arrhythmias following anaesthesia and surgery.

Methods

Horses with evidence of gastrointestinal disease undergoing an exploratory laparotomy and horses with no evidence of gastrointestinal disease undergoing orthopaedic surgery between September 2009 and January 2011 were recruited prospectively. A telemetric electrocardiogram (ECG) was fitted to each horse following recovery from anaesthesia and left in place for 24 hours. Selected electrolytes were measured before, during and after surgery and data was extracted from clinical records for analysis. Recorded ECGs were analysed and the arrhythmias characterised. Multivariable logistic regression was used to identify risk factors associated with the development of arrhythmias.

Results

Sixty-seven horses with gastrointestinal disease and 37 without gastrointestinal disease were recruited. Arrhythmias were very common during the post-operative period in both groups of horses. Supra-ventricular and bradyarrhythmias predominated in both groups. There were no significant differences in prevalence of any type of arrhythmias between the horses with or without gastrointestinal disease. Post-operative tachycardia and sodium derangements were associated with the development of any type of arrhythmia.

Conclusions

This is the first study to report the prevalence of arrhythmias in horses during the post-operative period in a clinical setting. This study shows that arrhythmias are very common in horses following surgery. It showed no differences between those horses with or without gastrointestinal disease. Arrhythmias occurring in horses during the post-anaesthetic period require further investigation.