Effects of repeated biopsying on muscle tissue in horses

Abstract

Summary The collection of muscle samples in horses to estimate their performance potential, adaptations to training and diagnosis of exertional myopathies is of increasing interest. This study was designed to examine whether repeated biopsying of the gluteus medius muscle at 7 week intervals alters morphology and muscle fibre variables in the sampling area. The gluteus had been biopsied 3 times previously, each biopsy separated by a 7 week interval. Seven weeks after the last biopsy, this study was initiated. Percutaneous needle biopsies were taken from left and right muscles at 2 depths (2 and 6 cm) and at 2 sites for each depth (22 and 25 cm from the tuber coxae) of 7 mature Thoroughbreds. The 22 cm site was located close (2 cm caudal) to an area of the muscle that had been biopsied previously. The 25 cm site was 5 cm apart from this area. A total of 52 samples were available for histology, electron microscopy and immunohistochemistry. The latter was used to study percentages, sizes and capillaries of muscle fibre types. Most muscle samples collected (75%) had normal morphology, but the remaining 25% showed signs of muscle repair. In some circumstances, they showed regenerative signs of complete muscle repair, while in others ineffective muscle repair (scar formation) was evident. Nevertheless, sufficient normal tissue was always available for measuring routine muscle variables. Samples collected 3 cm laterally apart showed large differences with regard to muscle fibre type variables examined. These results show that repeated muscle samples in intervals of 7 weeks do not have effects that would impair evaluation of muscle fibre variables for diagnosis of effectivity of conditioning programmes. Furthermore, they emphasise that the only way of keeping variations through sample collection technique small is to standardise all biopsying techniques accurately.

Effect of gluteus medius muscle sample collection depth on postprandial mammalian target of rapamycin signaling in mature Thoroughbred mares

“…13 Previous measures of gluteus medius fiber type composition in Thoroughbreds revealed 0% to 35% type I fibers, 26% to 61% type IIA fibers, and 10% to 79% type IIX fibers in the gluteus medius muscle, depending on biopsy depth. 3,13,32 In the Thoroughbred mares of the present study, the percentage of the various fiber types at each depth were near the midpoints the aforementioned ranges. 3,13,32 Previous research has also shown that although the degree of intrasubject variation can be minimized through standardization of biopsy sites, 32,33 a high degree of intersubject variation exists in fiber type composition at any given biopsy site or depth.…”

“…3,13,32 In the Thoroughbred mares of the present study, the percentage of the various fiber types at each depth were near the midpoints the aforementioned ranges. 3,13,32 Previous research has also shown that although the degree of intrasubject variation can be minimized through standardization of biopsy sites, 32,33 a high degree of intersubject variation exists in fiber type composition at any given biopsy site or depth. 2,3,33 We also found that individual horses of the same breed differed in the actual percentage of each fiber type at each biopsy depth.…”

“…Another possible explanation relates to the actual site within the muscle where the biopsy was performed. Many external landmarks have been used to standardize the biopsy site of the gluteus medius in horses, including one-third to two-thirds of the distance between the tuber coxae and the tailhead, 3,34 10 to 25 cm caudodorsal from the tuber coxae, 1,12,32 and in the region between the tuber sacrale and tuber coxae. 34,35 A previous study 34 revealed variation in the MHC composition of the gluteus medius muscle, even at a constant depth, with biopsy specimens obtained from the muscle region.…”

Alterations in mitochondrial respiratory function in response to endurance training and endurance racing

“…2000). Effect of endurance training on skeletal muscle histochemistry is strongly influenced by breed of the horse, intensity of training and sample collection site and depth (Lindner et al . 2002).…”

Needle muscle biopsy: technique validation and histological and histochemical methods for evaluating canine skeletal muscles

“…Greig et al (1985) have indicated that this procedure has the potential for use in the diagnosis, clinical management, and research activities relative to nutrition, metabolism, and neuromuscular diseases. Biopsies repeated within a seven-week interval permitted evaluation of equine muscle tissue (LINDNER et al, 2002); thus, evaluation of training programs, age effects Needle muscle biopsy: technique validation and histological and histochemical methods for evaluating canine skeletal... and/or pathology evolution was possible, without injuries to the animals.…”