Fasciola hepatica in UK horses.

BACKGROUND: Fasciola hepatica (liver fluke) affects grazing animals including horses but the extent to which it affects UK horses is unknown. OBJECTIVES: To define how liver fluke affects the UK horse population. STUDY DESIGN: Descriptive, cross-sectional, observational study. METHODS: An F. hepatica excretory-secretory antibody detection ELISA with a diagnostic sensitivity of 71% and specificity of 97% was validated and used to analyse serum samples. An abattoir study was performed to determine prevalence. A case-control study of 269 horses compared fluke exposure between horses with liver disease and controls. Data on clinical signs and blood test results were collected for sero-positive horses. Genotyping of adult fluke was used to produce a multilocus genotype for each parasite. RESULTS: Four (2.2%) of 183 horses registered in the UK, sampled in the abattoir, had adult flukes in the liver, and the sero-prevalence of F. hepatica was estimated as 8.7%. In the case-control study, horses showing signs consistent with liver disease had significantly higher odds of testing positive for F. hepatica on ELISA than control horses. In 23 sero-positive horses, a range of non-specific clinical signs and blood test abnormalities was reported, with a third of the horses showing no signs. Genotypic analysis of liver flukes from horses provided evidence that these came from the same population as flukes from sheep and cattle. MAIN LIMITATIONS: Bias could have arisen in the prevalence and case-control studies due to convenience sampling methods, in particular the geographic origin of the horses. Only a small number of horses tested positive so the data on clinical signs are limited. CONCLUSIONS: Exposure to liver fluke occurs frequently in horses and may be an under-recognised cause of liver disease. Flukes isolated from horses are from the same population as those found in ruminants. When designing and implementing parasite control plans, fluke should be considered, and horses should be tested if appropriate.

The effect of muscle hypoperfusion-hyperemia on repetitive vertical jump performance.

Alterations in skeletal muscle blood flow can greatly influence exercise performance. Brief periods of arterial hypoperfusion and subsequent hyperemia (hypoperfusion-hyperemia) have been shown to decrease the rate of skeletal muscle fatigue in a model of repeated, isometric wrist flexion exercise. However, the mechanism by which hypoperfusion-hyperemia influences dynamic motor skills remains unknown. The purpose of this study was to determine the effects of brief hypoperfusion-hyperemia (by femoral cuff occlusion) on repetitive vertical jump performance. Recreationally trained men and women (n = 10, mean +/- SD age, 25 +/- 2 years), performed 2 randomly assigned jumping trials, each consisting of 40 maximal effort vertical jumps. Jump height was videotaped on a Sony digital video recorder and analyzed with the Scion Images program. Trial 1 consisted of 40 vertical jumps without femoral artery occlusion. Trial 2 consisted of 40 vertical jumps preceded by femoral artery cuff occlusion for 90 seconds at 200 mm Hg, followed by 10 seconds of hyperemia before jumping. For both trials, the rate of decline in power output in men and women was approximately 20%. Hypoperfusion-hyperemia had no significant effect on vertical jumping power output, perhaps because additional muscle groups used to jump vertically (e.g., gluteals and arms) were not occluded. These results warrant further research on the effect of hypoperfusion-hyperemia on strength and power measures.

Brief muscle hypoperfusion/hyperemia: an ergogenic aid?

The purpose of this study was to investigate how short-duration forearm hypoperfusion/hyperemia affects isometric wrist flexion maximal voluntary contraction (MVC) in humans. Fourteen subjects (7 men and 7 women) performed isometric wrist flexion MVC on a Biodex ergometer under 2 experimental conditions: (a) without preceding forearm blood pressure cuff occlusion (control), or (b) immediately following forearm blood pressure cuff occlusion (2 minutes at 200 mm Hg) with 10 seconds of hyperemia (postocclusion). The mean MVC was greater in the postocclusion trial for both men (men, control = 267 +/- 57 J vs. postocclusion = 303 +/- 48 J; p < 0.05) and women (women, control = 185 +/- 21 J vs. postocclusion = 237 +/- 21 J; p < 0.005). The delta MVC between control and postocclusion trials was similarly increased in men and women (men, 36 +/- 13 J vs. women, 52 +/- 11 J; p = not significant [NS] between genders). When men and women were coupled as a single group, the MVC was approximately 20% greater in the postocclusion trial compared with the control trial (control = 226 +/- 31 J vs. postocclusion = 270 +/- 27 J; p < 0.0005). With Doppler/ultrasound imaging, brachial artery flow following 2 minutes of forearm occlusion was five- to sixfold greater than baseline blood flow (p < 0.0005). Isometric wrist flexion MVC is improved in both men and women following brief duration forearm cuff occlusion. The hyperemia that follows cuff occlusion may provide this putative effect.