This study demonstrates for the first time the presence of an L-amino acid oxidase (LAAO) enzyme in equine spermatozoa that is able to generate significant amounts of reactive oxygen species (ROS) and create a state of oxidative stress. RT-PCR analysis revealed that the mRNA for this enzyme was present in the equine testis and spermatozoa, while immunocytochemical studies demonstrated that the mature LAAO protein was located in the sperm head, particularly in the acrosomal and postacrosomal domains. Experimental studies demonstrated that the aromatic amino acids (L-phenylalanine > L-tryptophan > L-tyrosine) were substrates for this enzyme, eliciting the dose- and time-dependent generation of ROS via mechanisms that were enhanced by cell death. This unexpected result was confirmed by analyses of ROS generation in subcellular sperm fractions, which again located a majority of LAAO activity to the sperm head. Equine cryopreservation medium was shown to contain sufficient quantities of aromatic amino acids to activate the LAAO system and generate ROS. The biological significance of this activity was established in an experiment in which physiological concentrations of aromatic amino acids were found to suppress sperm motility but only if dead spermatozoa were present in the same suspension. The combination of aromatic amino acids and nonviable cells was also found to enhance the levels of lipid peroxidation in live spermatozoa. These results suggest the potential significance of LAAO activity in generating the oxidative stress associated with the cryopreservation of equine spermatozoa. It is possible that inhibitors of this enzyme system may facilitate the development of modified cryostorage regimes for clinical validation in vivo.

The transition into the clinical environment is challenging and associated with significant stress and anxiety. This study aimed to examine the perspectives of students on the characteristics important for preparedness for clinical learning and the influence of gender, age, and graduate status on those perspectives. This descriptive, questionnaire-based study of 62 characteristics categorised into six themes was conducted within the Surrey School of Veterinary Medicine completed by 139 students commencing their final clinical year. The Friedman test and post-hoc Wilcoxon signed rank sum test explored for differences in ranking across the themes. Ordinal logistic regression and Mann-Whitney U pairwise comparisons were utilised to investigate for effects of gender, age, and graduate status on theme ranking. There was a significant difference (P <0.05) between medians for themes of preparedness characteristics with comparisons revealing willingness and communication and interaction as the most highly rated characteristics. Knowledge and understanding were viewed as the least important characteristic. Regression and pairwise Mann-Whitney U comparisons confirmed no significant effects (P >0.05) of gender, age or graduate status on student rating of preparedness characteristics. Integrating learning opportunities of those preparedness characteristics in the pre-clinical curriculum may improve students’ preparedness for the clinical environment.

ObjectivesTo evaluate the effect of premedication with intravenous chlorphenamine on blood transfusion outcome in dogs; specifically, for transfusion associated complications (TAC). MethodsA retrospective observational study was performed at a UK University referral hospital between 2009 and 2019. Canine patients that received either whole blood (WB) or packed red blood cells (PRBC) were identified through databases searches. Information recorded included signalment, pretreatment with chlorphenamine, other medication administered and cause of anaemia. TAC and various transfusion variables were also recorded; temperature, pulse, respiratory rate and blood pressure before, during and after transfusion, pre-and post-transfusion packed cell volume (PCV), haemoglobin, serum bilirubin and urinalysis, duration and rate of transfusion and survival to discharge. ResultsA total of 56 dogs received 77 blood transfusions. The prevalence of TAC was 20.8% for all transfusions and 21.4% for first transfusion events. Febrile non haemolytic transfusion reactions (FNHTR), followed by vomiting post transfusion were most frequent. The percentage of TAC was 25.0% for dogs receiving PRBC compared with 13.8% for those receiving WB. There was no significant difference found between those pre-medicated with chlorphenamine and those that were not for TAC (P = 0.393), survival to discharge (P = 0.377), post-transfusion PCV (P = 0.213), specific TAC (type 1 hypersensitivity reactions (P = 0.680)) or when dogs received immunosuppressants (P = 0.590). Statement (conclusions)The prevalence of TAC was consistent with previous literature; these were mild and often selflimiting. In addition, this study suggested no indication for prophylactic chlorphenamine prior to canine blood transfusions.