Swiss warmblood horse with symptoms of hereditary equine regional dermal asthenia without mutation in the cyclophylin B gene (PPIB)

Hereditary equine dermal asthenia (HERDA) is an autosomal recessive skin disease that affects predominantly Quarter Horses and related breeds. Typical symptoms are easy bruising and hyperextensible skin on the back. The prognosis is guarded, as affected horses cannot be ridden normally and are often euthanised. In the Quarter Horse, HERDA is associated with a mutation in cyclophilin B (PPIB), an enzyme involved in triple helix formation of collagen. Here we describe the case of a Swiss Warmblood filly with symptoms of HERDA without PPIB-mutation and in which we also could exclude Ehlers-Danlos syndrome Type IV, VI, VIIA, VIIB and VIIC (dermatosparaxis type) as etiological diseases.

Genome-wide analysis reveals selection for important traits in domestic horse breeds.

Intense selective pressures applied over short evolutionary time have resulted in homogeneity within, but substantial variation among, horse breeds. Utilizing this population structure, 744 individuals from 33 breeds, and a 54,000 SNP genotyping array, breed-specific targets of selection were identified using an F(ST)-based statistic calculated in 500-kb windows across the genome. A 5.5-Mb region of ECA18, in which the myostatin (MSTN) gene was centered, contained the highest signature of selection in both the Paint and Quarter Horse. Gene sequencing and histological analysis of gluteal muscle biopsies showed a promoter variant and intronic SNP of MSTN were each significantly associated with higher Type 2B and lower Type 1 muscle fiber proportions in the Quarter Horse, demonstrating a functional consequence of selection at this locus. Signatures of selection on ECA23 in all gaited breeds in the sample led to the identification of a shared, 186-kb haplotype including two doublesex related mab transcription factor genes (DMRT2 and 3). The recent identification of a DMRT3 mutation within this haplotype, which appears necessary for the ability to perform alternative gaits, provides further evidence for selection at this locus. Finally, putative loci for the determination of size were identified in the draft breeds and the Miniature horse on ECA11, as well as when signatures of selection surrounding candidate genes at other loci were examined. This work provides further evidence of the importance of MSTN in racing breeds, provides strong evidence for selection upon gait and size, and illustrates the potential for population-based techniques to find genomic regions driving important phenotypes in the modern horse.

Seven novel KIT mutations in horses with white coat colour phenotypes

White coat colour in horses is inherited as a monogenic autosomal dominant trait showing a variable expression of coat depigmentation. Mutations in the KIT gene have previously been shown to cause white coat colour phenotypes in pigs, mice and humans. We recently also demonstrated that four independent mutations in the equine KIT gene are responsible for the dominant white coat colour phenotype in various horse breeds. We have now analysed additional horse families segregating for white coat colour phenotypes and report seven new KIT mutations in independent Thoroughbred, Icelandic Horse, German Holstein, Quarter Horse and South German Draft Horse families. In four of the seven families, only one single white horse, presumably representing the founder for each of the four respective mutations, was available for genotyping. The newly reported mutations comprise two frameshift mutations (c.1126_1129delGAAC; c.2193delG), two missense mutations (c.856G>A; c.1789G>A) and three splice site mutations (c.338-1G>C; c.2222-1G>A; c.2684+1G>A). White phenotypes in horses show a remarkable allelic heterogeneity. In fact, a higher number of alleles are molecularly characterized at the equine KIT gene than for any other known gene in livestock species.

Ultrastructural mitochondrial alterations in Equine myopathies of unknown origin.

Background: Very few mitochondrial myopathies have been described in horses. Objective: To examine the ultrastructure of muscle mitochondria in equine cases of myopathy of unknown origin. Materials & methods: Biopsies of vastus lateralis of the Musculus quadriceps femoris were taken predominantly immediately post mortem and processed for transmission electron microscopy. As a result, electron micrographs of 90 horses in total were available for analysis comprising 4 control horses, 16 horses suffering from myopathy and 70 otherwise diseased horses. Results: Following a thorough clinical and laboratory work-up, four out of five patients that did not fit into the usual algorithm to detect known causes of myopathy showed ultrastructural mitochondrial alterations. Small mitochondria with zones with complete disruption of cristae associated with lactic acidemia were detected in a 17-year-old pony mare, extremely long and slender mitochondria with longitudinal cristae in a 5-year-old Quarter horse stallion, a mixture of irregular extremely large mitochondria (measuring 2500 by 800 nm) next to smaller ones in an 8-year-old Hanoverian mare and round mitochondria with only few cristae in a 11-year-old pony gelding. It remains uncertain whether the subsarcolemmal mitochondrial accumulations observed in the fifth patient have any pathological significance. Conclusions: Ultrastructural alterations in mitochondria were detected in at least four horses. To conclude that these are due to mitochondrial dysfuntions, biochemical tests should be performed. Practical applications: The possibility of a mitochondrial myopathy should be included in the differential diagnosis of muscle weakness.

Evolutionary Genomics and Conservation of the Endangered Przewalski's Horse.

Przewalski's horses (PHs, Equus ferus ssp. przewalskii) were discovered in the Asian steppes in the 1870s and represent the last remaining true wild horses. PHs became extinct in the wild in the 1960s but survived in captivity, thanks to major conservation efforts. The current population is still endangered, with just 2,109 individuals, one-quarter of which are in Chinese and Mongolian reintroduction reserves [1]. These horses descend from a founding population of 12 wild-caught PHs and possibly up to four domesticated individuals [2-4]. With a stocky build, an erect mane, and stripped and short legs, they are phenotypically and behaviorally distinct from domesticated horses (DHs, Equus caballus). Here, we sequenced the complete genomes of 11 PHs, representing all founding lineages, and five historical specimens dated to 1878-1929 CE, including the Holotype. These were compared to the hitherto-most-extensive genome dataset characterized for horses, comprising 21 new genomes. We found that loci showing the most genetic differentiation with DHs were enriched in genes involved in metabolism, cardiac disorders, muscle contraction, reproduction, behavior, and signaling pathways. We also show that DH and PH populations split ∼45,000 years ago and have remained connected by gene-flow thereafter. Finally, we monitor the genomic impact of ∼110 years of captivity, revealing reduced heterozygosity, increased inbreeding, and variable introgression of domestic alleles, ranging from non-detectable to as much as 31.1%. This, together with the identification of ancestry informative markers and corrections to the International Studbook, establishes a framework for evaluating the persistence of genetic variation in future reintroduced populations.

Fatal Left Ventricular Rupture and Pericardial Tamponade Following a Horse Kick to the Chest

ABSTRACT: Horse kicks are rare incidents-especially, if they end in fatality. In this case, a 13-year-old girl collapsed 3 minutes after sustaining a kick to the chest from a pony. Resuscitation attempts were unsuccessful. Postmortem computed tomography and magnetic resonance imaging were performed before autopsy.Imaging revealed a 3-cm long laceration of the left ventricle and a large pericardial effusion. Using segmentation techniques, the amount of blood inside the pericardium was determined. These findings correlated well with the autopsy findings. Pericardial tamponade was determined at autopsy to be the cause of death.Postmortem imaging may prove useful for the diagnosis of these types of injury, but further studies are needed to document accuracy.

Pulmonary edema at recovery after colic operation with in-situ nasogastric tube in a horse

After an uneventful general anesthesia, in a horse negative pressure pulmonary edema developed due to acute upper airway obstruction during the anesthetic recovery phase after colic surgery. No pathologic alteration of respiration was observed until the horse stood up and began suffocating. The horse had recovered with the nasogastric tube in situ. This, together with the postmortem diagnosis of laryngeal hemiplegia resulted in impairment of airflow through the larynx and development of pulmonary edema. Our objective is to alert clinicians about the possible hazard of recovery with an in-situ nasogastric tube.

Epidemiological and genetic study of exertional rhabdomyolysis in a Warmblood horse family in Switzerland

REASONS FOR PERFORMING STUDY: Exertional rhabdomyolysis (ER) and its familial basis in Warmblood horses is incompletely understood. OBJECTIVES: To describe the case details, clinical signs and management of ER-affected Warmblood horses from a family with a high prevalence of ER, to determine if histopathological signs of polysaccharide storage myopathy (PSSM) and the glycogen synthase (GYS1) mutation are associated with ER in this family, and to investigate potential risk factors for development of ER. METHODS: A family consisting of a sire with ER and 71 of his descendants was investigated. History of episodes of ER, husbandry, feeding and use was assessed by interviewing horse owners using a standardised questionnaire. All horses were genotyped for GYS1. In 10 ER-affected horses, muscle histopathology was evaluated. RESULTS: Signs of ER were reported in 39% of horses and 51% of the entire family possessed the GYS1 mutation. Horses possessing the GYS1 mutation had a 7.1-times increased risk for developing ER compared to those with the normal genotype (95% confidence interval [CI] 2.37-21.23, P = 0.0005). All muscle samples from horses in the family with ER showed polysaccharide accumulation typical for PSSM, amylase-resistant in 9/10 cases. There was evidence (odds ratio 5.6, CI 1.00-31.32, P = 0.05) that fat or oil feeding improved clinical signs of ER. No other effects of environmental factors associated with clinical signs of ER were identified. CONCLUSION AND POTENTIAL RELEVANCE: PSSM associated with the GYS1 mutation is one identifiable cause of ER in Warmblood horses. Signs of ER are not always manifest in GYS1 positive horses and there are also other causes for ER in Warmblood horses. Breeding animals with the GYS1 mutation results in a high prevalence of ER due to its dominant mode of inheritance.

Genetic diversity in an indigenous horse breed: implications for mating strategies and the control of future inbreeding

The Franches-Montagnes is an indigenous Swiss horse breed, with approximately 2500 foalings per year. The stud book is closed, and no introgression from other horse breeds was conducted since 1998. Since 2006, breeding values for 43 different traits (conformation, performance and coat colour) are estimated with a best linear unbiased prediction (BLUP) multiple trait animal model. In this study, we evaluated the genetic diversity for the breeding population, considering the years from 2003 to 2008. Only horses with at least one progeny during that time span were included. Results were obtained based on pedigree information as well as from molecular markers. A series of software packages were screened to combine best the best linear unbiased prediction (BLUP) methodology with optimal genetic contribution theory. We looked for stallions with highest breeding values and lowest average relationship to the dam population. Breeding with such stallions is expected to lead to a selection gain, while lowering the future increase in inbreeding within the breed.

Comparative human-horse sequence analysis of the CYP3A subfamily gene cluster

Cytochrome P450 enzymes (CYP450s) represent a superfamily of haem-thiolate proteins. CYP450s are most abundant in the liver, a major site of drug metabolism, and play key roles in the metabolism of a variety of substrates, including drugs and environmental contaminants. Interaction of two or more different drugs with the same enzyme can account for adverse effects and failure of therapy. Human CYP3A4 metabolizes about 50% of all known drugs, but little is known about the orthologous CYP450s in horses. We report here the genomic organization of the equine CYP3A gene cluster as well as a comparative analysis with the human CYP3A gene cluster. The equine CYP450 genes of the 3A family are located on ECA 13 between 6.97-7.53 Mb, in a region syntenic to HSA 7 99.05-99.35 Mb. Seven potential, closely linked equine CYP3A genes were found, in contrast to only four genes in the human genome. RNA was isolated from an equine liver sample, and the approximately 1.5-kb coding sequence of six CYP3A genes could be amplified by RT-PCR. Sequencing of the RT-PCR products revealed numerous hitherto unknown single nucleotide polymorphisms (SNPs) in these six CYP3A genes, and one 6-bp deletion compared to the reference sequence (EquCab2.0). The presence of the variants was confirmed in a sample of genomic DNA from the same horse. In conclusion, orthologous genes for the CYP3A family exist in horses, but their number differs from those of the human CYP3A gene family. CYP450 genes of the same family show high homology within and between mammalian species, but can be highly polymorphic.

A quarter century experience in liver trauma: a plea for early computed tomography and conservative management for all hemodynamically stable patients

Advances in diagnostic imaging and the introduction of damage control strategy in trauma have influenced our approach to treating liver trauma patients. The objective of the present study was to investigate the impact of change in liver trauma management on outcome.

Seroprevalence of Babesia caballi and Theileria equi in the Swiss horse population

In Switzerland, the prevalence and incidence of equine piroplasma parasite (EPP) infections are unknown. In order to obtain a first insight into the prevalence, a representative sample of 689 sera of horses from Switzerland was serologically tested for the presence of antibodies directed against T. equi and B. caballi using the Indirect Fluorescence Antibody Test (IFAT). A total of 50 (7.3%) horses were seropositive for EPP: overall, the seroprevalence of T. equi was significantly higher than that of B. caballi (p=0.002). The seropositivities in indigenous horses (animals bred and raised in Switzerland) and in imported horses were 4.8% (11/230) and 8.5% (39/459), respectively. Unlike in indigenous horses, where no significant difference in seroprevalences could be observed between the two parasite species, the seroprevalence of T. equi was significantly higher (p<0.001) than that of B. caballi in imported horses. Horses imported from France, Spain and Portugal exhibited a significantly higher seroprevalence, and horses imported from Germany a significantly lower seroprevalence of EPP compared to indigenous horses. There were no associations between sex, age, weight loss, surgery or blood transfusions with T. equi and B. caballi seroprevalences. The overall seroprevalence of 7.3% clearly shows that infection with EPP is a threat to the health of the horses in Switzerland. With the presumed expansion of permissive tick vectors, EPP infections will potentially increase in importance in the future. Therefore, continuous monitoring is mandatory.

Proteomic and peptidomic study of proteolysis in quarter milk after infusion with lipoteichoic acid from Staphylococcus aureus

Mastitic milk is associated with increased bovine protease activity, such as that from plasmin and somatic cell enzymes, which cause proteolysis of the caseins and may reduce cheese yield and quality. The aim of this work was to characterize the peptide profile resulting from proteolysis in a model mastitis system and to identify the proteases responsible. One quarter of each of 2 cows (A and B) was infused with lipoteichoic acid from Staphylococcus aureus. The somatic cell counts of the infused quarters reached a peak 6h after infusion, whereas plasmin activity of those quarters also increased, reaching a peak after 48 and 12h for cow A and B, respectively. Urea-polyacrylamide gel electrophoretograms of milk samples of cow A and B obtained at different time points after infusion and incubated for up to 7 d showed almost full hydrolysis of beta- and alpha(S1)-casein during incubation of milk samples at peak somatic cell counts, with that of beta-casein being faster than that of alpha(S1)-casein. Two-dimensional gel electrophoretograms of milk 6h after infusion with the toxin confirmed hydrolysis of beta- and alpha(S1)-casein and the appearance of lower-molecular-weight products. Peptides were subsequently separated by reversed-phase HPLC and handmade nanoscale C(18) columns, and identified by matrix-assisted laser desorption/ionization time-of-flight tandem mass spectrometry. Twenty different peptides were identified and shown to originate from alpha(s1)- and beta-casein. Plasmin, cathepsin B and D, elastase, and amino- and carboxypeptidases were suggested as possible responsible proteases based on the peptide cleavage sites. The presumptive activity of amino- and carboxypeptidases is surprising and may indicate the activity of cathepsin H, which has not been reported in milk previously.

Cross-sectional study of Streptococcus species in quarter milk samples of dairy cows in the canton of Bern, Switzerland

A total of 2538 quarter milk samples from 638 lactating dairy cows from 47 farms in the canton of Bern, Switzerland, were investigated for streptococci. A novel, simple and inexpensive laboratory method was used for the differentiation of Streptococcus species, and a risk factor analysis was carried out. The prevalence in the quarter milk samples was 0.2 per cent for Streptococcus agalactiae, 1.3 per cent for Streptococcus uberis, 1.3 per cent for Streptococcus dysgalactiae, 0.1 per cent for Enterococcus species and 2.9 per cent for minor Streptococcus species (designated Streptococcus-Lactococcus-Enterococcus [SLE] group). Based on the somatic cell count (SCC), S uberis and S dysgalactiae were classified as 'major' pathogens and the bacteria in the SLE group as 'minor' pathogens. For S uberis, S dysgalactiae and bacteria in the SLE group, the most significant risk factor was an intramammary infection (IMI) of a neighbouring quarter by the same pathogen. Other significant risk factors for S uberis infection were a positive California Mastitis Test (CMT) result and a SCC of more than 100,000 cells/ml. Significant risk factors for IMI with S dysgalactiae were a positive CMT result, teat injury and palpable abnormalities in the udder. Infection with bacteria in the SLE group was significantly associated with a SCC of more than 100,000 cells/ml, a lactation number of more than 2, the right rear quarter (as the location of infection) and a positive CMT result.