Characterisation of phenotypic patterns in equine exercise-associated myopathies.

BACKGROUND: Equine exercise-associated myopathies are prevalent, clinically heterogeneous, generally idiopathic disorders characterised by episodes of myofibre damage that occur in association with exercise. Episodes are intermittent and vary within and between affected horses and across breeds. The aetiopathogenesis is often unclear; there might be multiple causes. Poor phenotypic characterisation hinders genetic and other disease analyses. OBJECTIVES: The aim of this study was to characterise phenotypic patterns across exercise-associated myopathies in horses. STUDY DESIGN: Historical cross-sectional study, with subsequent masked case-control validation study. METHODS: Historical clinical and histological features from muscle samples (n = 109) were used for k-means clustering and validated using principal components analysis and hierarchical clustering. For further validation, a blinded histological study (69 horses) was conducted comparing two phenotypic groups with selected controls and horses with histopathological features characterised by myofibrillar disruption. RESULTS: We identified two distinct broad phenotypes: a non-classic exercise-associated myopathy syndrome (EAMS) subtype was associated with practitioner-described signs of apparent muscle pain (p < 0.001), reluctance to move (10.85, p = 0.001), abnormal gait (p < 0.001), ataxia (p = 0.001) and paresis (p = 0.001); while a non-specific classic RER subtype was not uniquely associated with any particular variables. No histological differences were identified between subtypes in the validation study, and no identifying histopathological features for other equine myopathies identified in either subtype. MAIN LIMITATIONS: Lack of an independent validation population; small sample size of smaller identified subtypes; lack of positive control myofibrillar myopathy cases; case descriptions derived from multiple independent and unblinded practitioners. CONCLUSIONS: This is the first study using computational clustering methods to identify phenotypic patterns in equine exercise-associated myopathies, and suggests that differences in patterns of presenting clinical signs support multiple disease subtypes, with EAMS a novel subtype not previously described. Routine muscle histopathology was not helpful in sub-categorising the phenotypes in our population.

CONTEXTE: Les myopathies induites à l'exercice demeurent fréquentes, hétérogènes cliniquement et représentent des désordres idiopathiques caractérisés par des épisodes de dommages myofibrillaires en lien avec l'exercice. Les épisodes sont intermittents et varient à la fois chez le même cheval, entre chevaux et entre les différentes races. L'étiopathogénie demeure obscure et pourrait être multifactorielle. La pauvre caractérisation phénotypique des myopathies ne simplifie pas les analyses génétiques ni celles d'autres maladies. OBJECTIFS: Le but de cette étude est de caractériser les patrons phénotypiques en lien avec les myopathies induites à l'exercice chez le cheval. TYPE D'ÉTUDE: Étude transversale historique et étude subséquente de validation de cas témoins aveugle. MÉTHODES: Les facteurs clés cliniques et histologiques provenant d'échantillons de muscles (n = 109) ont été utilisés pour l'algorithme de K­moyennes et validés par le biais d'analyse des composantes principales et de classification hiérarchique. Pour validation additionnelle, une étude histologique à l'aveugle (69 chevaux) a été faite comparant les deux groupes phénotypiques avec des contrôles sélectionnés et des chevaux avec éléments histopathologiques caractérisés par de la discontinuité myofibrillaire. RÉSULTATS: Deux phénotypes distincts ont été identifiés: un premier sous­type de syndrome de myopathie induite à l'exercice non­classique (EAMS) associé à de la douleur musculaire telle que décrite par le praticien suivant le cheval (χ2 (df=1,n=109) = 19.33, p < 0.001), difficulté à se déplacer (χ2 (df=1,n=109) = 10.85, p = 0.001), démarche anormale (χ2 (df=1,n=109) = 34.61, p < 0.001), ataxie (χ2 (df=1,n=109) = 10.88, p = 0.001) et parésie (χ2 (df=1,n=109) = 10.88, p = 0.001); alors qu'un sous­type RER classique non­spécifique n'était associé à aucune variable en particulier. Aucune différente histologique n'a été identifié entre les sous­types dans l'étude de validation et aucune caractéristique histopathologique d'autres myopathies équines n'a été identifiées dans les différents sous­types. LIMITES PRINCIPALES: Aucune population indépendante pour validation; petite taille d'échantillon pour les sous­types peu nombreux identifiés; aucun cas contrôles positifs de myopathie fibrillaire; description des cas provenant de multiples praticiens indépendants et non­aveugles. CONCLUSION: Cette étude est la première utilisant des méthodes de regroupement informatique pour identifier des patrons phénotypiques de myopathies équines induites à l'exercice et suggère que des différences existent dans les patrons de signes cliniques en faveur de multiples sous­types de maladie, incluant EAMS qui représente un nouveau sous­type non décrit jusqu'à maintenant. L'histopathologie musculaire de routine n'a pas permis de sous­catégoriser les phénotypes dans cette population.

Pharmacological inhibition of acetylcholinesterase improves the locomotion defective phenotype of a SCA3 C. elegans model.

Inhibition of acetylcholinesterase (AChE) is a common used treatment option for Alzheimer's disease. However, there has been limited research on the potential use of AChE inhibitors for the treatment of Machado-Joseph disease (MJD)/Spinocerebellar Ataxia 3 (SCA3), in spite of the positive results using AChE inhibitors in patients with other inherited ataxias. MJD/SCA3, the most common form of dominant Spinocerebellar Ataxia worldwide, is caused by an expansion of the polyglutamine tract within the ataxin-3 protein, and is characterized by motor impairments. Our study shows that administration of the AChE inhibitor neostigmine is beneficial in treating the locomotion defective phenotype of a SCA3/MJD model of C. elegans and highlights the potential contribution of AChE enzymes to mutant ataxin-3-mediated toxicity.

Does inbreeding contribute to pregnancy loss in Thoroughbred horses?

BACKGROUND: Excessive inbreeding increases the probability of uncovering homozygous recessive genotypes and has been associated with an increased risk of retained placenta and lower semen quality. No genomic analysis has investigated the association between inbreeding levels and pregnancy loss. OBJECTIVES: To compare genetic inbreeding coefficients (F) of naturally occurring Thoroughbred Early Pregnancy Loss (EPLs), Mid and Late term Pregnancy Loss (MLPL) and Controls. The F value was hypothesised to be higher in cases of pregnancy loss (EPLs and MLPLs) than Controls. STUDY DESIGN: Observational case-control study. METHODS: Allantochorion and fetal DNA from EPL (n = 37, gestation age 14-65 days), MLPL (n = 94, gestational age 70 days-24 h post parturition) and Controls (n = 58) were genotyped on the Axiom Equine 670K SNP Genotyping Array. Inbreeding coefficients using Runs of Homozygosity (FROH) were calculated using PLINK software. ROHs were split into size categories to investigate the recency of inbreeding. RESULTS: MLPLs had significantly higher median number of ROH (188 interquartile range [IQR], 180.8-197.3), length of ROH (3.10, IQR 2.93-3.33), and total number of ROH (590.8, IQR 537.3-632.3), and FROH (0.26, IQR 0.24-0.28) when compared with the Controls and the EPLs (p < 0.05). There was no significant difference in any of the inbreeding indices between the EPLs and Controls. The MLPLs had a significantly higher proportion of long (>10 Mb) ROH (2.5%, IQR 1.6-3.6) than the Controls (1.7%, IQR 0.6-2.5), p = 0.001. No unique ROHs were found in the EPL or MLPL populations. MAIN LIMITATIONS: SNP-array data does not allow analysis of every base in the sequence. CONCLUSIONS: This first study of the effect of genomic inbreeding levels on pregnancy loss showed that inbreeding is a contributor to MLPL, but not EPL in the UK Thoroughbred population. Mating choices remain critical, because inbreeding may predispose to MLPL by increasing the risk of homozygosity for specific lethal allele(s).

The history and welfare of working mules in the valleys of the Toubkal massif, in the High Atlas of Morocco.

The appearance of the mule in the remote villages of the Toubkal National Park in the High Atlas Mountains of Morocco can be traced back to the early years of the twentieth century. The mule population's subsequent growth in numbers accompanied the shift away from a subsistence economy that was made possible by the appearance and growth of the mining and mountain tourism industries. This paper reviews this early history, drawing on the accounts provided by early explorers and anthropologists, before developing a mixed methods approach to evaluating the welfare of pack mules in two villages within the National Park. The first village is part of the main access route to the Toubkal, the principle summit of the National Park and therefore much visited. The second is a much more remote, under visited and less developed village. Ethnographic work, studying muleteering practice and undertaken over several years is reported here and supplemented by findings from a detailed survey of the mules of both villages. This allows the work undertaken and the lived realities of the working mule across several generations of inhabitants to be presented together with data about the primary welfare concerns identified on clinical examination. In village one, 72 mule owners and their mules were surveyed and examined. Many of these mules worked in tourism, providing a source of revenue for their families. This work was often undertaken by teenagers/young adults working their father's mules. Tethering was widely practised and evidence of tethering injuries were identified in most mules. In the more remote village, 18 owners and their equids were surveyed and examined. In this population, mules were more likely to be worked locally in agriculture, building and to collect firewood. Bitting injuries associated with the use of the traditional bit were a significant concern in both villages. The universal use of a closed shoe was also in evidence in both villages; this was associated with atrophy of the frog and hoof imbalances. The reasoning for the use of the traditional bit and closed shoe are presented and alternatives discussed.

Genetic characterisation of the Connemara pony and the Warmblood horse using a within-breed clustering approach.

BACKGROUND: The Connemara pony (CP) is an Irish breed that has experienced varied selection by breeders over the last fifty years, with objectives ranging from the traditional hardy pony to an agile athlete. We compared these ponies with well-studied Warmblood (WB) horses, which are also selectively bred for athletic performance but with a much larger census population. Using genome-wide single nucleotide polymorphism (SNP) and whole-genome sequencing data from 116 WB (94 UK WB and 22 European WB) and 36 CP (33 UK CP and 3 US CP), we studied the genomic diversity, inbreeding and population structure of these breeds. RESULTS: The k-means clustering approach divided both the CP and WB populations into four genetic groups, among which the CP genetic group 1 (C1) associated with non-registered CP, C4 with US CP, WB genetic group 1 (W1) with Holsteiners, and W3 with Anglo European and British WB. Maximum and mean linkage disequilibrium (LD) varied significantly between the two breeds (mean from 0.077 to 0.130 for CP and from 0.016 to 0.370 for WB), but the rate of LD decay was generally slower in CP than WB. The LD block size distribution peaked at 225 kb for all genetic groups, with most of the LD blocks not exceeding 1 Mb. The top 0.5% harmonic mean pairwise fixation index (FST) values identified ontology terms related to cancer risk when the four CP genetic groups were compared. The four CP genetic groups were less inbred than the WB genetic groups, but C2, C3 and C4 had a lower proportion of shorter runs of homozygosity (ROH) (74 to 76% < 4 Mb) than the four WB genetic groups (80 to 85% < 4 Mb), indicating more recent inbreeding. The CP and WB genetic groups had a similar ratio of effective number of breeders (Neb) to effective population size (Ne). CONCLUSIONS: Distinct genetic groups of individuals were revealed within each breed, and in WB these genetic groups reflected population substructure better than studbook or country of origin. Ontology terms associated with immune and inflammatory responses were identified from the signatures of selection between CP genetic groups, and while CP were less inbred than WB, the evidence pointed to a greater degree of recent inbreeding. The ratio of Neb to Ne was similar in CP and WB, indicating the influence of popular sires is similar in CP and WB.