Use of electromyography for the diagnosis of equine hyperkalemic periodic paresis.

The use of electromyography (EMG) as a diagnostic aid for equine hyperkalemic periodic paresis (EHPP) was investigated in seven affected and seven control horses. Affected horses were confirmed positive for EHPP either by elevated serum potassium concentration with clinical signs of myotonia, or by inducing hyperkalemia and clinical signs using oral potassium chloride challenge. All horses were asymptomatic at the time EMG was performed, using bipolar fine wire needle electrodes. The myopotentials were recorded on magnetic tape and displayed on paper charts for analysis. Insertional and resting activity were recorded from the right supraspinatus, triceps, extensor carpi radialis and gluteal muscles in standing horses. Myotonic discharges were seen in six of seven affected horses but not in any of the controls. All seven affected horses and two control horses had prolonged insertional activity. Five out of seven affected horses and one control horse displayed spontaneous motor unit discharges unrelated to recording electrode movement. Myoelectrical potentials containing closely timed muscle potentials, i.e. doublets, were found in all affected horses, with four of seven affected horses also showing triplets. These potentials were not observed in any of the controls. No obvious difference in activity was observed among the four muscle sites tested. It is concluded that EMG is a safe and useful tool for diagnosing EHPP in horses not currently displaying clinical signs. Myotonic discharges and doublets appear to be the most diagnostically significant electromyographic abnormalities in EHPP affected horses.     

Hyperkalemic periodic paralysis in horses

Eleven horses (3 mares, 7 stallions, 1 gelding) with clinical and biochemical evidence of hyperkalemic periodic paralysis were studied. Each horse had history of episodic weakness, muscular tremors, or collapse, which lasted for periods of a few minutes to hours. Diagnosis was based on hyperkalemia in association with a spontaneous episode of paralysis or by precipitation of an episode by oral administration of potassium chloride. Clinical and biochemical events were documented during spontaneous and induced episodes of muscular weakness. During episodes, electrocardiographic findings were consistent with hyperkalemia. Electromyography performed between episodes revealed fibrillation potentials and positive sharp waves, complex repetitive discharges, and myotonic discharges. Histologic changes in muscle biopsy specimens varied from no overt changes in some horses to vacuolation in type-2B fibers with mild degenerative changes in other horses. Electron microscopy of myofibers revealed dilatations of the sarcoplasmic reticulum. Analysis of blood samples taken serially during induced attacks in 5 horses revealed marked hyperkalemia (5.5 to 9.0 mEq/L), with normal acid-base status, hemoconcentration, and modest changes in muscle-derived enzymes. Close correlation (r2 = 0.882) between total plasma protein and plasma potassium concentrations was observed and indicated a shift of fluid out of the extracellular fluid compartment. Treatment of either spontaneous or induced episodes by IV administration of calcium, glucose, or bicarbonate resulted in rapid recovery. Dietary management or daily administration of acetazolamide effectively controlled episodes. An affected mare was bred to an affected stallion, and 3 affected offspring were produced by embryo transfer. Blood samples from another extended family of affected horses were analyzed for identification of a genetic marker.(ABSTRACT TRUNCATED AT 250 WORDS)     

Familial incidence of hyperkalemic periodic paralysis in quarter horses.

The pedigrees of 17 horses with hyperkalemic paralysis were studied. All were first-, second-, or third-generation offspring of a common sire, 16 were registered Quarter Horses. Analysis indicated that it was unlikely that the concentration of hyperkalemic periodic paralysis in the offspring of this sire was attributable to chance. The familial nature of this condition should help veterinarians diagnostically. It also suggests that it is possible to reduce the incidence of this condition by breeding from non-affected lines of horses and reinforces the need for studies to determine whether the disease is genetic in origin. Although more affected horses were second-generation offspring, the proportion of horses affected was largest in the first generation and decreased progressively with each generation. This is probably because horses in the earlier generations have been observed for longer periods and thus clinical signs are more likely to have been noticed in these horses.     

Electrodiagnostic evaluation in feline hypertrophic muscular dystrophy

Standard needle electromyography (EMG) of 56 muscles and nerve conduction velocities (NCV) of the ulnar and common peroneal nerves were investigated in each of six cats affected with hypertrophic feline muscular dystrophy, 10 related heterozygote carriers and 10 normal cats. The EMG findings were considered normal in carrier and control cats, and consisted of 33% normal readings, 22% myotonic discharges, 18% fibrillation potentials, 11% prolonged insertional potentials, 10% complex repetitive discharges and 6% positive sharp waves in affected cats. Muscles of the proximal limbs were most frequently affected. No differences in NCV were found between the three cat groups. It was concluded that dystrophin-deficient dystrophic cats have widespread and frequent EMG changes, predominantly myotonic discharges and fibrillation potentials, which are most pronounced in the proximal appendicular muscles.     

Episodic muscle tremors in a quarter horse: resemblance to hyperkalemic periodic paralysis

A three year old Quarter Horse stallion was presented with a one year history of episodes of generalized muscle tremors and stiffness, and spasm of the muscles of facial expression, lasting 10-15 minutes. Between attacks, the horse was either normal or had a localized muscle tremor in the flank region. Episodes appeared unrelated to exercise. The major abnormal findings included 1) a rise in plasma potassium from a resting level of 4.4 to 7.9 mmol/L during an attack and 2) electromyographic findings of generalized increased insertion activity and myotonic discharges. The horse was treated with hydrochlorothiazide tablets for nine months, during which time no further attacks were noted. However, four months after the drug was stopped, sporadic focal muscle tremors reappeared; two months later, generalized attacks were seen. Despite reinstitution of the diuretic, a focal flank tremor persisted. Two related horses in the same stable also were reported by the owner to exhibit sporadic generalized muscle twitching. The abnormal findings of the present case differ from clinical syndromes previously reported in horses. Some similarities to hyperkalemic periodic paralysis in humans are noted.     

Hyperkalaemic periodic paralysis in homozygous and heterozygous horses: a co-dominant genetic condition

Historical, clinical and experimental data were collected from 9 horses homozygous for HYPP (H/H). All showed episodes of respiratory stertor, described as a rattling or honking sound, usually within the first week post partum. Five horses had one or more episodes of dysphagia, in 3 horses this was accompanied by drooling and in 3 by weight loss. In comparison, only one of 35 contemporaneous half siblings (of which approximately half would be expected to be of the H/N genotype and half N/N) was observed to have respiratory stertor prior to weaning and none had problems with dysphagia. One mature homozygous stallion was infertile secondary to urospermia. Six homozygous horses died or were subjected to euthanasia; 4 age less than a year, one age 20 months and one age 5 years. The remaining 3 cases were still alive at the end of the study. A comparison of homozygous and heterozygous horses using standardised potassium chloride challenge testing indicated that during attacks homozygotes showed significantly more frequent signs of drooling, prolapse of the third eyelid, respiratory stridor and weakness than heterozygous horses. Homozygotes also had significantly more total abnormalities (including myotonic discharges, high frequency repetitive discharges, and spontaneous activity) on electromyographic examination than heterozygotes. These data imply that HYPP is inherited as a codominant genetic defect, because the homozygotes showed more severe clinical signs of disease than heterozygotes. Homozygous foals would be expected to be produced in 25% of matings in which both parents are heterozygous. Owners and veterinarians should be aware of the risks of this mating.     

Genetic variability in Hanoverian warmblood horses using pedigree analysis

A data set constituting a total of 310,109 Hanoverian warmblood horses was analyzed to ascertain the genetic variability, coefficients of inbreeding, and gene contributions of foreign populations. The reference population contained all Hanoverian horses born from 1980 to 2000. In addition, Hanoverian stallions born from 1980 to 1995 and Hanoverian breeding mares from the birth years 1980 to 1995 with registered foals were analyzed for the same genetic parameters. The average complete generation equivalent was approximately 8.43 for the reference population. The mean coefficient of inbreeding was 1.33, 1.19, and 1.29% for the reference population, stallions, and breeding mares, respectively. The effective number of founders was largest in stallions (364.3) and smallest in the reference population (244.9). The ratio between the effective number of founders and the effective number of ancestors was 3.15 for the reference population, 3.25 for the stallions, and 3.06 for the breeding mares. The effective population size in the Hanoverian warmblood reference population was 372.34. English Thoroughbreds contributed nearly 35% of the genes to the Hanoverian reference population and even slightly greater contributions (39%) to the stallions. Trakehner and Arab horses contributed approximately 8 and 2.7%, respectively, to the Hanoverian gene pool. The most important male ancestors were Aldermann I from the A/E line, Fling from the F/W line, and Absatz from the Trakehner line, whereas the breeding mare Costane had the greatest contribution to the reference population, stallions, and breeding mares. From 1996 onward, the stallions Weltmeyer and Donnerhall had the largest genetic impact on the Hanoverian horse population.     

Equine hyperkalemic periodic paralysis: review and implications.

The purpose of this review is to present an up-to-date summary of the signs, diagnosis, treatment, and implications of equine hyperkalemic periodic paralysis. The review encompasses all original articles published between 1986 and early 1993. Hyperkalemic periodic paralysis is the result of a genetic mutation in the skeletal muscle sodium channel gene. It is inherited as an autosomal dominant trait; most affected horses are heterozygotes. The classical signs are muscle fasciculation, spasm, and weakness associated with hyperkalemia. However, these signs are only rarely observed in affected horses. Potential sequelae to attacks are abrasions and involuntary recumbency; these problems are not specific for hyperkalemic periodic paralysis, but they occur more frequently in hyperkalemic periodic paralysis-affected horses. It is also likely that hyperkalemic periodic paralysis results in greater muscle mass. There are suggestions that homozygotes may be more severely affected and show signs of upper respiratory obstruction as foals. The practitioner needs to be aware of the tests for hyperkalemic periodic paralysis, and their limitations, so that he can properly diagnose this condition. The industry has the difficult problem of deciding whether or not testing should be mandatory and the fate of positive horses.     

Evaluation of a signal-adapted filter for processing of periodic electromyography signals in horses walking on a treadmill.

OBJECTIVE: To evaluate an adaptive-filter method for use in analysis of periodic electromyography (EMG) signals in which the transfer function of the filter is matched to characteristics of the signal. ANIMALS: 15 adult horses without clinical signs of back pain. PROCEDURE: Electromyography signals of the left and right longissimus dorsi muscles, middle gluteal muscles, and triceps brachii muscle were recorded from horses walking on a treadmill, using bilaterally placed surface electrodes. A reflective marker was placed on the hoof of the left hind limb for simultaneous kinematic measurement of motion cycles. Absolute value of the measured EMG signal was convoluted by use of a filter signal equivalent to the length of 3 motion cycles. The signal-to-noise ratio (SNR) was calculated from the autocorrelation function and compared with the SNR of the unfiltered and the low-pass filtered signals. RESULTS: The signal-adapted filter significantly increased SNR (by 7.3 dB, compared with the low-pass filter, and by 11.1 dB, compared with the unfiltered EMG signal). CONCLUSIONS AND CLINICAL RELEVANCE: The signal-adapted filter eliminates signal parts that are not correlated to periodic motion. The method reported here improves the applicability of periodic EMG signals as a clinical tool.     

高粱雄不育系与四种苏丹草杂种F1农艺性状及细胞遗传学研究

为明确雄不育系高粱(Sorghum bicolor(L.)Moench)Z3A、V4A与黑壳、白壳、红壳、棕壳4种苏丹草(Sorghum sudanense(Piper)Stapf)种间杂种F1的育性状况、细胞遗传学特征和育种潜力,为杂交后代选择利用提供依据,采用定株观测、花粉粒染色,染色体制片镜检等方法,对杂种F1代的生长发育、主要农艺性状及染色体构型等进行研究。结果表明:8个杂交组合F1代植株生长茁壮,平均株高350~386 cm,显著超过其双亲;生育期较长(132~134 d),属中晚熟类型;分蘖数多达6.24~6.82个,呈偏父本遗传;穗型呈双亲中间型,每穗小穗数、穗密度均优于其父本苏丹草;茎叶比在3.10~3.33之间,明显低于其母本;株高140 cm时,F1茎叶鲜草氢化物含量很低,变幅为9.38~42.01 mg.kg-1;开花盛期主茎糖锤度值较高,在8.89%~9.46%之间,呈偏母本遗传;F1花粉可育率在94%以上,自然结实率在73.22%~76.62%之间,均不存在育性问题;F1代PMCMⅠ染色体配对行为规则,平均构型为2n=2x=20(10Ⅱ),但其棒状二价比例较高(6.702~7.215),亲本间遗传组成存在一定差异;F1鲜草产量明显超过其父本苏丹草,增产幅度为12.17%~28.28%,超亲优势幅度为13.86%~39.42%。试验确定出育种潜力最大的杂交组合是:高粱V4A×棕壳苏丹草和高粱Z3A×黑壳苏丹草。     

Bilateral laryngeal paralysis in the horse

Four two-year-old Thoroughbreds suffered an acute gastrointestinal illness shortly after dosing with mineral oil which was thought to have been contaminated with an organophosphate compound. Three weeks later all four were noted to be dyspnoeic and endoscopic examination showed that they had developed bilateral laryngeal paralysis. Two of the horses died during severe bouts of dyspnoea six and eight months later and the third was killed shortly thereafter. Examination of the left and right recurrent laryngeal nerves from these horses showed a severe loss of myelinated fibres distally, especially in the left nerve. A similar but less severe lesion was seen in other long peripheral nerves, including the phrenic and digital nerves of the third horse. The spinal cord in two horses showed evidence of mild axonal degeneration which was not related to a particular tract or location. The fourth horse had bilateral laryngeal paralysis two years later. The acute clinical signs and delayed neurological sequelae seen in these horses were strongly suggestive of accidental organophosphate toxicity.     

应用血液蛋白多态型剖析仿土仔鸡繁育体系

本研究以广东地方品种杏花鸡为主要亲本的广源鸡繁育体系为材料,采用电泳分析方法,测定了血浆淀粉酶(Amy-1、Amy-2)、碱性磷酸酶(Akp-1、Akp-2)、酯酶(ES-1)和血红蛋白(Hb)等6项蛋白质遗传标记的多态型。对繁育体系各成员各位点的基因频率、多样度、遗传距离等进行的计算,采用系统聚类、模糊聚类及主坐标分析等数值分类方法,对杂交效果从生化角度进行评析。试验结果表明,杂交商品仔鸡与各亲本均有一定联系,但最接近于第二父系杏花鸡。     

HYPP: hyperkalemic periodic paralysis in the horse

Hyperkalaemic periodic paralysis(HYPP) is characterized by intermittent episodes of muscular tremor, weakness, and collapse, and is probably caused by abnormal electrolyte transport in the muscle cell membrane. During an episode of HYPP, most animals are severely hyperkalaemic. HYPP is a hereditary disease and occurs only in American Quarter horses or crossbreds. Because these horses are now being imported into the Netherlands, HYPP should be included in the differential diagnosis of horses showing signs of muscle tremor, paresis, or paralysis. The present article reviews the literature on HYPP and describes a case showing typical signs of the disease.     

清远麻鸡与矮小隐性白羽蛋鸡杂交后代羽色及生长性能的研究

为开发清远麻鸡的多重杂交遗传潜能,突破父母代制种模式的单一,适应市场需求,研究观测了清远麻鸡(♂)与矮小隐性白羽蛋鸡(♀)杂交F₁代的羽色、体尺及生产性能指标,重点探讨了杂交F₁代羽色的遗传以及生产性能的改良。结果显示:杂交F₁代初生时以麻色为主,占比71.58%,杂交F₁代的成年公鸡和母鸡均出现了羽色分化或变异;杂交F₁代母鸡体重和体型均比其母本矮小隐性白羽蛋鸡更大;F₁代公鸡体重小于其父本清远麻公鸡。清远麻鸡与矮小隐性白羽蛋鸡的杂交F₁代母鸡具有较好的杂交性能,通过进一步的横交固定选育,有望培育出替代清远麻鸡纯种的父母代亲本。     

基于微卫星多重PCR技术的特克塞尔×哈萨克杂交羊亲子鉴定

本研究旨在建立一套适用于特克塞尔×哈萨克杂交羊亲子关系的鉴定体系。试验选取11个微卫星标记位点进行组合扩增，通过优化微卫星标记位点组合的引物浓度、退火温度及反应体系等条件，建立了4组多重PCR体系，对多重PCR扩增产物采用毛细管电泳进行基因型分型，经PROSize3.0软件读取基因型分型结果，Cervus 3.0软件分析群体的遗传多样性，鉴定特克塞尔×哈萨克级进F2代（特哈级进F2）和横交F2代（特哈横交F2）的亲子关系。结果表明，特哈级进F2和特哈横交F2的等位基因数为180和140、平均等位基因数为16.364和12.727、平均观测杂合度（Ho）为0.533和0.544、平均期望杂合度（He）为0.807和0.831、平均多态信息含量（PIC）为0.783和0.803。对特哈级进F2和特哈横交F2两个品种70只候选亲本和64只候选子代的11个微卫星标记位点进行亲子关系鉴定，结果表明：当双亲基因型未知时的累积排除概率（CE-1P）为0.9995和0.9997；当单亲基因型已知时的累积排除概率（CE-2P）均达到1.0000；双亲基因型已知的累计排除概率（CEPP）均达到1.0000。说明选择的11个微卫星标记位点具有高度的多态性和较高的排除概率，适用于遗传分析和个体的亲子鉴定。利用微卫星标记建立的特克塞尔×哈萨克杂交羊亲子鉴定体系为分析绵羊群体遗传多样性和辅助育种工作提供了理论依据。     

Electromyographic activity of cubital joint muscles in horses during locomotion

Electromyographic (EMG) activity of 4 muscles of the cubital joint and the strain of forelimb hooves were recorded telemetrically in 4 Thoroughbreds (with and without a rider) standing, walking, trotting, and cantering. Bipolar fine wire electrodes were inserted into the muscles, and strain gauges were attached to the hoof wall. Motion pictures (16 mm), synchronized with EMG tracings, were taken to obtain kinematic data. When horses were standing, the biceps brachii had tonic activity, but the brachialis and the caput longum and the caput laterale of the triceps brachii had no EMG activity. The biceps brachii had EMG activity during the stance phase. The brachialis had EMG activity from the end of the stance phase to the middle of the swing phase. Unlike the biceps brachii, the brachialis acted as a flexor muscle of the cubital joint during locomotion. The EMG activity of the caput longum of the triceps brachii was detected from midswing phase to early stance phase. The EMG activity of the caput laterale of the triceps brachii began in midswing or late-swing phase and ceased in early stance or midstance phase. During locomotion, caput longum EMG activity always preceded caput laterale activity. When horses were cantering, the brachialis and the caput longum (acting mainly in the swing phase) had an EMG activity phase different from those in leading and trailing forelimbs. These 4 muscles had similar EMG activity patterns during locomotion in horses with and without a rider.     

Pedigree analysis in the Austrian Noriker draught horse: genetic diversity and the impact of breeding for coat colour on population structure

The pedigree of the current Austrian Noriker draught horse population comprising 2808 horses was traced back to the animals considered as founders of this breed. In total, the number of founders was 1991, the maximum pedigree length was 31 generations, with an average of 12.3 complete generations. Population structure in this autochthonous Austrian draught horse breed is defined by seven breeding regions (Carinthia, Lower Austria, Salzburg, Styria, Tyrol, Upper Austria and Vorarlberg) or through six coat colour groups (Bay, Black, Chestnut, Roan, Leopard, Tobiano). Average inbreeding coefficients within the breeding regions ranged from 4.5% to 5.5%; for the colour groups, the coefficients varied from 3.5% to 5.9%. Other measures of genetic variability like the effective number of founders, ancestors and founder genomes revealed a slightly different genetic background of the subpopulations. Average coancestries between and within breeding areas showed that the Salzburg population may be considered as the nucleus or original stock whereas all other subpopulations showed high relationship to horses from Salzburg. The target of draught horse breeding in the 21st century does not meet the breeding concept of maximizing genetic gains any more. Stabilizing selection takes place. In this study, we show that demographic factors as well as structure given by different coat colours helped to maintain genetic diversity in this endangered horse breed.     

Sound signature for identification and quantification of upper airway disease in horses

OBJECTIVE: To investigate whether upper airway sounds of horses exercising with laryngeal hemiplegia and alar fold paralysis have distinct sound characteristics, compared with unaffected horses. ANIMALS: 6 mature horses. PROCEDURE: Upper airway sounds were recorded in horses exercising on a high-speed treadmill at maximum heart rate (HR(MAX)) under 3 treatment conditions (ie, normal upper airway function [control condition], and after induction of left laryngeal hemiplegia or bilateral alar fold paralysis) in a randomized crossover design. Fundamental frequency, spectrograms using Gabor transform, and intensity characteristics of acquired sounds (peak sound level [sound(peak] and highest frequency of at least -25 dB sound intensity [F(25max)]) were evaluated. RESULTS: Evaluation of the fundamental frequency of the time domain signal was not useful. Sensitivity and specificity (83 and 75%, respectively) of spectrograms were greatest at maximal exercise, but the exact abnormal condition was identified in evaluation of only 12 of 18 spectrograms. Increased accuracy was obtained using sound(peak) and F(25max) as discriminating variables. The use of sound(peak) discriminated between control and laryngeal hemiplegia conditions and F(25max) between laryngeal hemiplegia and alar fold paralysis conditions. This increased the specificity of sound analysis to 92% (sensitivity 83%) and accurately classified the abnormal state in 92% of affected horses. CONCLUSIONS AND CLINICAL RELEVANCE: Sound analysis might be a useful adjunct to the diagnosis and evaluation of treatment of horses with upper airway obstruction, but would appear to require close attention to exercise intensity. Multiple measurements of recorded sounds might be needed to obtain sufficient accuracy for clinical use.     

Evaluation of the quality of husbandry of Franches-Montagnes horses in their breeding farms

The quality of husbandry of Franches-Montagnes horses (FM) in Switzerland is evaluated on the basis of an investigation carried out in 2002 by the Swiss FM breeding federation. Questionnaires were sent to 3500 of its members and the results include data from 968 breeding enterprises, housing a total of 3965 FM: 46.1% were breeding mares (61.0% with foal at foot), 26.5% young stock, 1.3% stallions and 26.0% non breeding stock (74.6% of which were pleasure horses and 25.4% working horses). 57.6% of the FM were housed in individual boxes with or without permanent outdoor access, 25.4% were hold in groups with or without permanent outdoor access, the remaining 17.0% were kept in standing stalls. 95.0% of the FM had at least visual contact with other equines and 99.2% had sufficient light in their stable. 88.1% were stabled on long stalk straw, while only 4.3% were bedded on other materials other than straw. The average time spent at pasture per horse and per week ranged from 96.5 +/- 51.6 hours in summer to 27.2 +/- 26.7 hours in winter. On average, a FM is used for 8.3 +/- 6.5 hours per week. Horses with an paddock at their disposal spend an average of 39.8 +/- 45.9 hours there per week.     

Hyperkalaemic periodic paralysis in Australian Quarter Horses

SUMMARY Three Quarter Horse stallions and 5 of their 11 tested progeny were diagnosed as affected with the inherited autosomal dominant defect hyperkalaemic periodic paralysis in Victoria in 1992. The diagnoses were based on the appearance of clinical signs and associated increased plasma potassium concentrations in response to oral potassium loading. All affected horses were descendants of the American Quarter Horse Impressive. Indirect evidence indicates that at least 3 other affected Quarter Horse stallions have stood or are standing at stud in Australia. The clinical details of the affected horses are described and the size of the affected population in Australia is discussed.