Search

Reasons for performing study Cardiac arrhythmias are a recognised but poorly characterised problem in the Standardbred racehorse. Frequency data could aid the development of cardiac arrhythmia screening programmes. Objectives To characterise the occurrence of cardiac arrhythmias in Standardbreds prior to racing and in the late post race period using a handheld, noncontinuous recording device. Study design Prospective, observational study, convenience sampling. Methods Noncontinuous electrocardiographic recordings were obtained over a 12 week period from Standardbred horses competing at a single racetrack. Electrocardiograms were obtained before racing and between 6 and 29 min after the race using a handheld recording device. Prevalence of arrhythmias was calculated for all horses and overall frequency of arrhythmias was calculated for race starts and poor performers. Univariate logistic regression analysis was used to identify risk factors for cardiac arrhythmias. Results A total of 8657 electrocardiogram recordings were obtained from 1816 horses. Six horses had atrial fibrillation after racing (prevalence = 0.11%, frequency = 0.14%), one horse had supraventricular tachycardia before racing (prevalence = 0.06%, frequency = 0.02%), and 2 horses had ventricular tachyarrhythmias after racing (prevalence = 0.06%, frequency = 0.05%). The frequency of atrial fibrillation among race starts with poor performance was 1.3-2.0%. Increasing age was a significant risk factor for the presence of atrial premature contractions before racing and atrial fibrillation and ventricular ectopy after racing. Conclusions Both physiological and pathological cardiac arrhythmias can be detected in apparently healthy Standardbred horses in the prerace and late post race period using noncontinuous recording methods. Future studies should examine cumulative training or racing hours as a risk factor for cardiac arrhythmia. The prevalence and frequency information may be useful for track veterinarians and regulatory personnel following trends in cardiac arrhythmias. [ABSTRACT FROM AUTHOR]

Reasons for performing study: There is limited information regarding the impact of training track surface on the occurrence of stress fractures. Objectives: To evaluate the impact of training track surface on the proportion of long bone and pelvic stress fractures associated with lameness in Thoroughbred horses in flat race training undergoing nuclear scintigraphic examination. Study design: Retrospective study. Methods: Scintigraphic examinations of Thoroughbred flat racehorses were evaluated from 2 hospitals (hospital A [Toronto Equine Hospital], 2003-2009, and hospital B [George D. Widener Hospital for Large Animals, School of Veterinary Medicine, University of Pennsylvania], 1994-2006). Horses admitted to hospital A trained at a single track, at which the main training surface changed from dirt to synthetic on 27 August 2006. Two distinct populations existed at hospital B: horses that trained on dirt (numerous trainers) and those that trained on turf (single trainer). All scintigraphic images were evaluated by a blinded reviewer. Fisher's exact test and logistic regression were used when appropriate, and significance was set at P<0.05. Results: When reviewing 528 scintigraphic examinations from hospital A (257 dirt and 271 synthetic, numerous trainers), there was a greater proportion of stress fractures detected in scintigraphic examinations from horses training on a synthetic surface (31.7%) in comparison to scintigraphic examinations from horses training on a dirt surface (23.0%) at an earlier point in time (P = 0.03). There was a greater proportion of hindlimb/pelvic and tibial stress fractures diagnosed in horses from the synthetic surface-trained group than from the dirt-trained group at hospital A (P<0.04 and P = 0.03, respectively). Conclusions: This study provides evidence that training surface may affect the proportion of stress fractures diagnosed, but other factors, such as training philosophy, appear to be important. Future prospective investigations to fully elucidate the relationship between training track surface and the proportion of stress fractures and other nonfatal musculoskeletal injuries are warranted. [ABSTRACT FROM AUTHOR]

A procedure is described for solving an open, fully exchanging, three-compartment model representing ruminal volatile fatty acids (VFA) kinetics in sheep. This model was solved using results from a published study in which labelled VFA, viz. 1-14C-acetate (Ac), 1-14C-propionate (Pr) and 1-14C-butyrate (Bu), were infused individually at a constant rate for 240 min into the rumen of sheep on different occasions. During the tracer infusions, the sheep were given 75 g of lucerne (Medicago sativa) every hour. The patterns of increasing specific radioactivity (SA) during the infusions were described by differential equations that were solved using the computer software, WinSAAM. This linear kinetic analysis gave estimates of the rates of synthesis and absorption of Ac, Pr and Bu and the carbon interconversions between each acid. The sizes of the Ac, Pr and Bu compartments (10.5, 3.9 and 2.1 g C respectively), were also estimated, which is not possible with commonly used algebraic analyses. The model output showed that tracer : tracee equilibrium (plateau SA) had not been reached in the Ac, Pr and Bu compartments during the 240 min of tracer infusion and the algebraic method of analysis used in the original study was therefore compromised. The procedures described here eliminated this source of error; in addition, confidence in the model solution was improved because all data representing the build-up to plateau SA were used, rather than just estimates of ‘plateau’ SA. After accounting for VFA interconversions, the rates of VFA absorption (or incorporation into other materials such as microbial polymers or methane) were 85, 48 and 49 g C/day, or 78%, 91% and 73% of the total production of each VFA, respectively. The variability in the observed SA responses to the tracer infusions was relatively large and this is discussed. Model solutions using the linear kinetic analysis and the previously widely used algebraic analyses are compared. The effect of positional labelling in tracer VFA is also discussed in the light of evidence that the rate of absorption of Pr may be overestimated when [1-14C]-Pr rather than [2-14C]-Pr or uniformly labelled [14C]-Pr is used as the Pr tracer. [ABSTRACT FROM AUTHOR]