蒙古马mtDNA D-loop区遗传多样性与多重母系起源

【目的】对蒙古马mtDNA D-loop区247bp序列进行遗传多样性分析,探讨蒙古马的起源。【方法】采用PCR方法、测序技术及生物信息学方法,将本试验所测得的21匹蒙古马的mtDNA D-loop区序列,与GenBank中公布的43条蒙古马的对应序列,及世界范围内家马、普氏野马和内蒙古地区古马的mtDNA D-loop区序列一起进行系统发育分析。【结果】蒙古马具有39种单倍型,37个多态位点,核苷酸多样度(π)为0.02756±0.00967,单倍型多样度(h)为0.979±0.007,表明蒙古马mtDNA遗传多样性非常丰富。引用世界家马、古马、普氏野马和蒙古马共1074条mtDNA D-loop序列及本研究中21条mtDNA D-loop序列,共同进行系统发育分析,结果显示,蒙古马分布于A、B、C、D、E和F支系。【结论】蒙古马为多重母系起源,且与国内古马的母系起源几乎一致,推测蒙古马可能是中国北方家马的重要母系来源。     

Using magnetic resonance imaging to diagnose nondisplaced fractures of the second phalanx in horses

Two horses presented with a history of severe lameness that was localised to the area around the second phalanx (P2) of one forelimb. Radiographs of the second phalanx of both horses were unremarkable, apart from some smooth periosteal new bone production on the dorsum of P2. Magnetic resonance imaging revealed a non-displaced fracture of P2 in both horses. One horse was euthanased because of a poor prognosis for racing, but the second horse was treated conservatively and salvaged for breeding. Magnetic resonance imaging is a newer imaging modality in horses and may be useful in diagnosing cases of obscure lameness.     

The bispectral index during recovery from halothane and sevoflurane anaesthesia in horses

ObjectiveTo record the bispectral index (BIS) when horses moved during either halothane or sevoflurane anaesthesia and when they made volitional movements during recovery from these anaesthetics.Study designRandomized prospective clinical study.AnimalsTwenty-five client-owned horses undergoing surgery aged 8.8 (± 5.3; 1–19) years (mean ± SD; range).MethodsBaseline BIS values were recorded before pre-anaesthetic medication (BIS_B) and during anaesthesia (BIS_A) maintained with halothane (group H; n = 12) or sevoflurane (group S; n =13) at approximately 0.8–0.9 × minimum alveolar concentrations (MAC). Bispectral indices were recorded during the surgery when unexpected movement occurred (BIS_MA), during recovery when the first movement convincingly associated with consciousness was observed (BIS_M1) and once sternal recumbency was achieved (BIS_ST).ResultsNo significant difference in BIS_M1 was found between halothane- (85 ± 7; 75–93) and sevoflurane- (87 ± 10; 70–98) anaesthetized horses although BIS_A was significantly (p = 0.0002) lower in group S (62 ± 7; 53–72) than group H (74 ± 7; 60–84). Differences between BIS_M1 and BIS_A were significant in sevoflurane (p = 0.00001) and halothane recipients (p = 0.002) but were greater in group S (25 ± 9; 4–38) compared with group H (12 ± 10; ?9–25). In six of eight horses, BIS_MA values ranged between those recorded during anaesthesia and at first movement.Conclusions and clinical relevanceBispectral indices appear to approximate levels of unconsciousness, suggesting that monitoring the BIS may assist equine anaesthesia. However, it does not predict intra-operative movement.     

Genetic Structure of Severe Combined Immunodeficiency Carrier Horses in Morocco Inferred by Microsatellite Data

A total of 17 microsatellite deoxyribonucleic acid loci used routinely for horse parentage control were used to evaluate genetic diversity among normal Arabian horses and severe combined immunodeficiency (SCID) carrier Arabian horses (ArS) and normal Arab-Barb horses and SCID carrier Arab-Barb horses (ArbeS). On the basis of the genotype of 186 horses, mean allelic diversity was estimated as 6.82, 5.53, and 6.7059 in normal Arabian horses, ArS, and for both groups of Arab-Barb horses, respectively. Five specific alleles were observed in ArS and ArbeS, with one common with ArS at HMS6, whereas five alleles common between ArS and ArbeS had a high frequency. Expected and observed heterozygosity showed great heterogeneity in the population studied and were similar or higher when compared with other studies on Arabian horses. Coefficient of gene differentiation G_st of Nei associated with Nei’s genetic distance and multivariate correspondence analysis indicated a possible differentiation between the studied populations when analyzed separately according to breed. Probability of assignment of a horse to a specific group was assessed using a full and partial Bayesian approach. In all, 80.6% of Arab horses and 78.2% of Arab-Barb horses were assigned properly with a partial Bayesian test, which provided better results than the full one. These findings will be useful for identification of SCID carrier horses by using the microsatellite deoxyribonucleic acid loci used routinely for horse parentage control in our laboratory.     

Age at first start and racing career of a cohort of Australian Standardbred horses

OBJECTIVE Compare the career profiles of a cohort of Standardbred horses that first raced as 2-year-olds with those that started their racing careers at a later age. METHOD Retrospective analysis of the racing records of all foals born in New South Wales in the 2000 foaling season. RESULTS The career records of 999 horses were analysed. Almost half (43.9%) first raced as 2-year-olds and one-third (33.9%) as 3-year-olds. The median career duration for horses that first raced as 2-year-olds was 2.93 years (interquartile range (IQR) 2.70-3.16), which was significantly greater than the median for horses that first raced at 3, 4 or ≥5 years old (P < 0.001). Males, and horses that first raced as 2-year-olds, earned significantly more prize money than females or horses that started racing aged ≥3 years (P < 0.001). The population median number of career starts was 28.0 (IQR 8-64). Males, and horses that first raced as 2-year-olds, had significantly more career starts than females or horses that started racing aged ≥3 years (P < 0.001). CONCLUSION This study found no evidence suggesting that racing as a 2-year-old had a deleterious effect on a horse's racing career.