Dynamic respiratory endoscopy without treadmill in 68 performance Standardbred,Thoroughbred and saddle horses under natural training conditions

Reasons for performing study: High speed treadmill endoscopy provides a true assessment and diagnosis of the dynamic obstructions of the upper equine respiratory tract (DO‐URT). However, treadmills do not always allow reproduction of the exact conditions of dynamic collapse of the URT. The availability of on‐board endoscopes, which could be used without a treadmill, would make exercising endoscopy readily available to more equine practices. Objectives: To develop and validate an innovative endoscope which could be used for the examination of the URT at exercise in ridden and harnessed sport horses performing in natural conditions. Methods: Authors worked closely with engineers of a company manufacturing veterinary endoscopes. Over a 2‐year period several prototypes were tested on more than 20 cooperative horses performing either in trot, gallop, jumping or endurance. The final Dynamic Respiratory Scope (DRS) allows real‐time visualisation of the URT and video recordings for post test reviewing and archiving. The DRS was then tested in 2 equine livery yards. Performance horses presented for investigation of abnormal respiratory noises at exercise and/or poor performance were subjected to exercising endoscopy. Endoscopic images of the URT were recorded and video recordings of the URT were reviewed post test. Results: A total of 68 horses were examined: 39 harnessed Standardbred and 29 mounted horses (16 Thoroughbred and 13 saddle horses). Of these, 44 were diagnosed with a URT abnormality. Good quality videos were obtained even at maximum speed in all cases. The innovative insertion tube provided very stable images compared to those obtained with flexible video endoscopes on treadmills. Conclusions: This study validates the safety and the reliability of the DRS for imaging the equine URT during natural exercising conditions. Potential relevance: Most common causes of DO‐URT can be diagnosed easily during any type of performance without a treadmill and the DRS offers a great potential for further URT clinical research.     

Dynamic respiratory endoscopy of Standardbred racehorses during qualifying races

Reason for performing study: Examination of the equine upper airway during racing has not previously been documented. Objective: To describe the feasibility and appearance of the upper airways by overground respiratory endoscopic examination during racing conditions. Methods: Overground videoendoscopic examinations were performed on 46 Standardbred racehorses during qualifying races. Examined horses' speeds were recorded throughout the race with a portable GPS device. Results: The procedure did not interfere with performance as there were no significant differences in race times between races in which horses were examined with the endoscope in place and prior unexamined races. Airway obstructions during or after the race were documented in 21 horses. Most previously reported causes of upper airway obstruction were observed; surprisingly bilateral ventro‐medial arytenoid displacement (VMAD; n = 5) was seen during exercise as frequently as dorsal displacement of the soft palate (DDSP). Although DDSP (n = 10) was the most common diagnosis made, many displacements (n = 5) occurred after the race. Horses that demonstrated DDSP after the race had slower speeds than unaffected horses during the race. Conclusions: Racing endoscopy permits the diagnosis of upper airway obstructions without affecting performance. The occurrence of DDSP immediately after exercise may be clinically relevant. During racing VMAD may be an important anomaly. Potential relevance: Racing endoscopy could be used to correlate the sensitivity of diagnostic endoscopy during race‐training or treadmill examination. The pathogenesis and significance of VMAD deserves further investigation.     

Dynamic collapse of the upper respiratory tract: A review

Dynamic collapse of the upper respiratory tract is a common cause of poor performance in athletic horses. Most commonly, airway obstruction occurs during strenuous exercise when the upper respiratory tract is exposed to high pressure swings. In horses undertaking submaximal exercise, the pressures may also be increased due to flexion of the neck. The nasopharynx and larynx are particularly prone to dynamic collapse and a number of different forms of upper airway obstruction are now recognised. However, due to the dynamic nature of the collapse a definitive diagnosis is often not possible from resting observations alone.     

Dynamic respiratory endoscopy in 67 Thoroughbred racehorses training under normal ridden exercise conditions

Reasons for performing study: There are potential advantages to imaging the upper portion of the respiratory tract (URT) of horses during ridden exercise. With the advent of a wireless endoscope, this is now possible. However, there has been no detailed validation of the technique and findings have not been compared to ridden speed. Objectives: To assess the combined use of a Dynamic Respiratory Scope (DRS) and global positioning system (GPS) receiver for examining the URT of a group of Thoroughbred racehorses randomly selected from a single flat racehorse training establishment. Methods: Horses were selected randomly from a population of Thoroughbred horses in training at the same training yard. Endoscopic images of the URT were recorded during a ridden exercise test on an ‘all‐weather‐gallop’ and were reviewed post testing. Speed was measured using a wrist mounted GPS receiver. Results: A total of 67 (34%) of the 195 horses in training were examined. Endoscopic findings included: normal URT function (44 cases); dorsal displacement of the soft palate (DDSP) (13 cases); laryngeal asymmetry (4 cases); and axial deviation of the aryepiglottic folds (3 cases). Maximum speed obtained by individual horses ranged from 41.8–56.3 km/h. Ridden speed was variably affected by DDSP. Conclusions: The DRS provides a safe effective system for imaging the equine URT during ridden exercise at speed. The abnormalities of the URT identified were similar to those observed during treadmill endoscopy studies reported in the literature. The effect of URT abnormalities on ridden speed requires further investigation. Potential relevance: This technique can be used to diagnose common causes of URT associated with poor performance in horses during normal training. This has substantial implications for future clinical diagnosis and treatment of URT pathology.     

Standardised exercise testing in 17 reining horses: Musculoskeletal,respiratory, cardiac and clinicopathological findings

Exercise testing can be useful to evaluate poor performance, as a preventative medicine tool, and in the assessment of training progression. A comprehensive exercise testing protocol that simultaneously evaluates common causes of poor performance has not been described in reining horses. The objective of this study was to describe the results of a standardised exercise testing protocol in reining horses. Seventeen reining horses that were part of a western performance intercollegiate team and had met the trainer's expectations during the athletic season were evaluated using a comprehensive standardised exercise test. Systems assessed included musculoskeletal system, upper respiratory tract, lower respiratory tract and cardiovascular system. These systems were assessed by means of historical questionnaires, general physical examinations, subjective lameness examinations, gait analysis using digital body mounted inertial sensors, resting and dynamic upper airway endoscopy, bronchoalveolar lavage fluid cytology, echocardiograms, resting and exercising electrocardiography, and laboratory tests (packed cell volume, lactate, creatine kinase and serum amyloid A). Subclinical abnormalities were detected frequently. The musculoskeletal system was the most commonly affected system, but cardiovascular and upper and lower airway abnormalities were also detected in some horses. These results suggest that exercise tests may be useful to detect subclinical abnormalities in horses used for reining. Further evaluation of both normally and poorly performing horses is necessary to determine if exercise testing can improve the health, performance and welfare of horses used for reining.     

Behavioural assessment of pain in 66 horses,with and without a bit

Horses can be ridden with or without a bit. Comparing the behaviour of the same horse in different modes constituted a ‘natural experiment’. Sixty-nine behaviours in 66 bitted horses were identified as induced by bit-related pain and recognised as forms of stereotypic behaviour. A prototype questionnaire for the ridden horse was based on 6 years of feedback from riders who had switched from a bitted to a bit-free bridle. From a template of 69 behavioural signs of pain derived from answers to the questionnaire, the number of pain signals shown by each horse, first when bitted and then bit-free, was counted and compared. After mostly multiple years of bit usage, the time horses had been bit-free ranged from 1 to 1095 days (median 35). The number of pain signals exhibited by each horse when bitted ranged from 5 to 51 (median 23); when bit-free from 0 to 16 (median 2). The number of pain signals for the total population when bitted was 1575 and bit-free 208; an 87% reduction. Percentage reduction of each of 69 pain signals when bit-free, ranged from 43 to 100 (median 87). The term ‘bit lameness’ was proposed to describe a syndrome of lameness caused by the bit. Bit pain had a negative effect on proprioception, i.e. balance, posture, coordination and movement. Only one horse showed no reduction in pain signals when bit-free. The welfare of 65 of 66 horses was enhanced by removing the bit; reducing negative emotions (pain) and increasing the potential to experience positive emotions (pleasure). Grading welfare on the Five Domains Model, it was judged that – when bitted – the population exhibited ‘marked to severe welfare compromise and no enhancement’ and – when bit-free – ‘low welfare compromise and mid-level enhancement.’ The bit-free data were consistent with the ‘one-welfare’ criteria of minimising risk and preventing avoidable suffering.     

Application of a Ridden Horse Pain Ethogram to horses competing at 5-star three-day-events: Comparison with performance

A Ridden Horse Pain Ethogram (RHpE) was previously developed to facilitate the detection of musculoskeletal pain. The objectives were to apply the RHpE during warm-up for the dressage phase of two 5* three-day events and to correlate the RHpE scores with subsequent performance. It was hypothesised that there would be a higher rate of failure to complete the cross-country phase in horses which exhibited ≥7 behaviours compared with those showing <7 behaviours. The RHpE, comprising 24 behaviours, was applied for 10–12 min during warm-up. Gait abnormalities in trot and canter were recorded. Dressage penalties, cross-country performance, showjumping penalties and final placings were documented. Horses were categorised as those which completed cross-country, or those which did not complete because of elimination or retirement. RHpE scores (n = 137) ranged from 0 to 9/24 (median 3 [range 0–9] for nonlame horses; median 5 [range 1–9] for horses with gait abnormalities in trot or canter). There was a moderate correlation between dressage penalty scores and the RHpE score (rho = 0.4, P<0.001, Spearman rank). Fifty-nine per cent of horses (n = 10/17) with a RHpE score ≥7 failed to complete cross-country, compared with 33% (n = 39/117) with a score <7. Horses that failed to complete the cross-country phase had higher RHpE scores compared with those that completed (P = 0.04, W = 8.3, Kruskal–Wallis; pairwise comparison Bonferroni, P = 0.06). There was a significant (rho = 0.3) relationship between total RHpE score and final horse placings (n = 80, P<0.01, Spearman rank). Horses with lameness or gait abnormalities in canter had significantly higher RHpE scores (P<0.01, χ² = 35, chi-square test) compared with other horses. There was a strong correlation between the RHpE scores for horses which competed at both events (P<0.001, rho = 0.6, Spearman rank). The RHpE should facilitate earlier identification of horses which may benefit from diagnosis and treatment, resulting in improvement in both performance and equine welfare.     

Lower respiratory tract disease in Thoroughbred racehorses: analysis of endoscopic data from a UK training yard

REASON FOR PERFORMING STUDY: There has been much research directed at potential causative agents and the epidemiology of lower respiratory tract disease (LRTD), but few reports of the clinical progression and outcome. OBJECTIVES: To define clinical features of LRTD in racehorses, including association with age and average duration of disease, through the analysis of endoscopic data. METHODS: A retrospective analysis of records from a single training yard of endoscopic examinations undertaken over a 2-year period was performed. Horses were subjected to regular endoscopic examination for a variety of reasons, and all horses placed on antibiotic therapy for lower respiratory tract disease were rescoped following treatment. Data analysed included a 0-8 tracheal mucus score based on visible endoscopic mucus and gross tracheal lavage turbidity, as well as age and treatment duration and type. RESULTS: A total of 522 endoscopic examinations undertaken on 123 horses and tracking 169 episodes of lower respiratory tract disease were recorded. Mean duration of disease episode was 15.5 days (median = 11 days, range = 4-61 days). Horses age 2 years were significantly more likely than those age > or=3 years to have at least one episode of respiratory disease (P<0.001). There was a direct association between initial tracheal mucus score and rescope score after treatment. CONCLUSIONS: Lower respiratory tract disease was more common in 2-year-olds than in older horses. Affected horses had endoscopic evidence of increased tracheal mucus accumulation for an average of 15.5 days per episode, a considerably shorter period than that suggested by previous studies. POTENTIAL RELEVANCE: Endoscopic examinations permit longitudinal tracking of lower respiratory tract disease in Thoroughbred racehorses. A prolonged duration of disease, sometimes extending for months, can be expected in a small proportion of cases, some of which appear to be refractory to treatment. There is a clear need for evidence-based analysis of treatment regimes to assist clinicians in decision making when managing disease in both individual and group situations.     

Effects of porcine reproductive and respiratory syndrome vaccination in breeding-age animals

Little is known about the safety and efficacy of extra-label use of the modified live porcine reproductive-and-respiratory syndrome (PRRS) virus vaccine in gestating sows. Our purpose was to determine the impact of vaccination on reproductive performance in 54 herds in Ontario, Manitoba (Canada) and the mid-western United States that were PRRS-positive, PRRS-negative, or concurrently affected by an outbreak of PRRS when initially vaccinated. Majority-vaccinated herds vaccinated ≥50% but <100% of sows at one time, and limit-vaccinated herds vaccinated <50% of sows at one time. Most majority-vaccinated herds did not vaccinate sows in late gestation, and none vaccinated during the initial PRRS outbreak. Numbers of pigs born alive and weaned decreased when pregnant sows were vaccinated. The effect of vaccination on productivity in the gestation following vaccination depended on the vaccination protocol.     

Performance and rideability issues in horses as a manifestation of pain: A review of differential diagnosis and diagnostic approach

Nonspecific performance and rideability issues are more likely a manifestation of pain in the ridden horse rather than a true behavioural problem. A systematic and thorough investigation focusing on the potential presence of pain-related conditions is thus crucial in horses with such complaints. It can, however, be challenging to determine whether the complaint is indeed related to pain, where the pain is located, and what the underlying cause is. This review describes the challenges of pain recognition in ridden horses and summarises the recently developed ridden horse ethograms that might enable pain to be assessed in an objective, valid and reliable way. Furthermore, the differential diagnosis and diagnostic approach to horses presenting potentially pain-related performance and rideability issues are discussed.     

Clinical trials using a telemetric endoscope for use during over‐ground exercise: A preliminary study

Dynamic collapse of the upper respiratory tract (URT) is a common cause of poor performance in horses. These conditions occur predominantly during strenuous exercise when the URT is unable to maintain dilation in the face of high inspiratory pressures. In most cases, these disorders cannot be accurately diagnosed during a resting endoscopic examination. To date, a definitive diagnosis of dynamic URT obstructions has been possible only by performing an endoscopic examination during high‐speed treadmill exercise. However, recent technological advances now enable URT endoscopy to be performed while the horse is exercising in its normal environment.     

抗猪繁殖与呼吸综合征病毒转基因细胞系的建立

采用脂质体法将具有抑制猪繁殖与呼吸综合征病毒(PRRSV)复制的shRNA质粒pEGFP-N1-shRNA导入PK-15细胞中,经G418药物筛选后,分离扩增绿色荧光蛋白阳性细胞,获得抗PRRSV转基因PK细胞系。通过对转染方法和条件的优化,确立最佳的转染及筛选步骤;对得到的阳性转基因细胞进行冷冻-解冻,并作PCR检测。结果表明,G418最佳筛选浓度为600μg/mL,脂质体与质粒的最佳转染比例为7∶2,最佳转染时间为24 h。本研究成功建立抗PRRSV转基因细胞系,为进一步的功能验证及体细胞核移植奠定了基础。     

表达猪繁殖与呼吸综合征病毒CH-1a株核衣壳蛋白重组鸡痘病毒的构建

从含有猪繁殖与呼吸综合征病毒（PRRSV）核衣壳蛋白（N）的质粒扩增出N基因，构建禽痘病毒转移载体。该载体含有禽痘病毒早晚期启动子LP2EP2控制之下的PRRSVN基因、P11启动下的报告基因lacZ以及用于同源重组的禽痘病毒基因组的片段。在转移载体转染亲本病毒S—FPV-017感染的鸡胚成纤维细胞（CEF）之后，采用蓝色表型筛选的方法，筛选到表达N基因的重组病毒，并对其进行了6轮蚀斑纯化。PCR方法鉴定证明重组病毒的基因组中含有完整PRRSVN基因，间接免疫荧光试验证明了PRRSVN蛋白在重组病毒感染的CEF细胞中获得表达，本研究为猪繁殖与呼吸综合征非复制型疫苗的研制打下了基础。     

表达牛呼吸道合胞体病毒G蛋白基因的重组Ⅰ型牛疱疹病毒的构建与鉴定

为构建表达牛呼吸道合胞体病毒(BRSV)G蛋白基因的牛疱疹病毒Ⅰ型(BHV-1)重组病毒,本研究将人工合成的BRSV全长G蛋白基因编码序列插入到巨细胞病毒(CMV)启动子之下构建TK基因缺失转移载体。利用磷酸钙-DNA沉淀法将该转移载体与亲本病毒BHV-1/TK-/LacZ+的基因组DNA共转染牛鼻甲细胞后收获增殖的病毒。通过反向蚀斑筛选,得到重组病毒BHV-1/TK-/G+。PCR检测结果证实G蛋白基因已经插入到了亲本病毒BHV-1/TK-/LacZ+的基因组中,间接免疫荧光试验和western blot证实BHV-1/TK-/G+中的G蛋白基因在感染的细胞中获得了表达。本研究为研制BRSV及其他重要牛传染病的BHV-1病毒活载体疫苗奠定了基础。     

The Seroprevalence of Canine Influenza Virus H3N8 in Dogs Participating in a Flyball Tournament in Pennsylvania in 2010: A Follow‐Up Study

Background

Canine influenza virus (CIV) H3N8 infection is thought to be highly contagious and potentially deadly. Low seroprevalence in dogs participating in the sport of flyball in 2009 was reported. It remains unknown if prevalence is changing in dogs at risk.

Objective

To determine seroprevalence of antibodies to CIV H3N8 in a population of pet dogs that participated in an indoor flyball tournament in Pennsylvania in November 2010.

Animals

Dogs participating in a flyball tournament.

Methods

Medical, travel, and activity histories for previous 10.5 months were obtained from consenting owners and serum samples were collected from dogs. Antibodies to CIV H3N8 were measured using hemagglutination inhibition.

Results

Of 251 competing dogs, 103 dogs were tested. Overall, seroprevalence of CIV H3N8 in dogs participating in flyball was 1.9% (95% CI, 0.05–6.8%). Thirty‐five dogs were tested in both 2009 (all titers <8) and 2010 (all titers <8). Ten of 103 dogs had been vaccinated for CIV H3N8. Two dogs had positive titers (>8) and both had been vaccinated twice in the previous month. Titers in remaining 8 vaccinated dogs were undetectable. Seroprevalence in vaccinated dogs was 20% (95% CI, 5.7–50.1%), whereas in unvaccinated dogs it was 0% (95% CI, 0–4.0%). Although 7 dogs had history of respiratory signs, only 1, which was vaccinated, was serologically positive for CIV H3N8.

Conclusions

Consistent with low prevalence of CIV H3N8 exposure previously reported in flyball dogs, unvaccinated dogs had 0% prevalence, suggesting a stable exposure rate. However, low seroprevalence may result in unprotected flyball dogs at risk for developing CIV H3N8.     

Assessment of stiffness and strength of 4 different implants available for equine fracture treatment: a study on a 20 degrees oblique long-bone fracture model using a bone substitute

OBJECTIVE: To compare the mechanical properties of 4 stabilization methods for equine long-bone fractures: dynamic compression plate (DCP), limited contact-DCPlate (LC-DCP), locking compression plate (LCP), and the clamp-rod internal fixator (CRIF--formerly VetFix). STUDY DESIGN: In vitro mechanical study. SAMPLE POPULATION: Bone substitute material (24 tubes) was cut at 20 degrees to the long axis of the tube to simulate an oblique mid-shaft fracture. METHODS: Tubes were divided into 4 groups (n=6) and double plated in an orthogonal configuration, with 1 screw of 1 implant being inserted in lag fashion through the "fracture". Thus, the groups were: (1) 2 DCP implants (4.5, broad, 10 holes); (2) 2 LC-DCP implants (5.5, broad, 10 holes); (3) 2 LCP implants (4.5/5.0, broad, 10 holes) and 4 head locking screws/plate; and (4) 2 CRIF (4.5/5.0) and 10 clamps in alternating position left and right of the rod. All constructs were tested in 4-point bending with a quasi-static load until failure. The implant with the interfragmentary screw was always positioned on the tension side of the construct. Force, displacement, and angular displacement at the "fracture" line were determined. Construct stiffness under low and high loads, yield strength, ultimate strength, and maximum angular displacement were determined. RESULTS: None of the implants failed; the strength of the bone substitute was the limiting factor. At low loads, no differences in stiffness were found among groups, but LCP constructs were stiffer than other constructs under high loads (P=.004). Ultimate strength was lowest in the LCP group (P=.01), whereas yield strength was highest for LCP constructs (409 N m, P=.004). CRIF had the lowest yield strength (117 N m, P=.004); no differences in yield strength (250 N m) were found between DCP and LC-DCP constructs. Differences were found for maximum angular displacement at the "fracture" line, between groups: LPC相似文献   

Effects of levonorgestrel‐quinestrol (EP‐1) treatment on Mongolian gerbil wild populations: a case study

Rodent pest population outbreaks occur frequently in grassland ecosystems in northern China. The Mongolian gerbil (Meriones unguiculatus) is a dominant pest rodent which is distributed across the semi‐desert grasslands of Inner Mongolia, China. In 2009, we studied the contraceptive effect of levonorgestrel‐quinestrol (EP‐1), concentration 50 ppm, on a wild Mongolian gerbil population. The one‐off contraceptive treatment was compared with a control group using a semi‐monthly live trapping method in the Ordos Semi‐desert Grassland Region of Inner Mongolia. The results show that juveniles were not recruited in spring in the treatment group. Ratios of juveniles in the control and treatment groups showed significant semi‐monthly differences from spring to summer (one‐way ANOVA, F_{2, 14}= 7.53, P < 0.05). Between both groups, annual fluctuations of juvenile and total population densities were significantly different respectively (F_{2, 14}= 4.64, P < 0.05; F_{2, 18}= 7.72, P < 0.05). The contraceptive EP‐1 delayed the normal reproductive pattern of Mongolian gerbil populations. This suppressed birth rates of gerbil populations, reduced their densities, and changed their age structures. The period of EP‐1 baiting should be extended but it could be an ideal method for controlling Mongolian gerbil populations during each breeding season.