American Miniature Research Articles

Immortalization of American miniature horse-derived fibroblast by cell cycle regulator with normal karyotype.

Immortalized cells serve as a crucial research tool that capitalizes on their robust proliferative properties for functional investigations of an organism. Establishing an immortalized American miniature horse cell line could yield valuable insights into these animals' genetic and physiological characteristics and susceptibility to health issues. To date, immortalized small horse cells with normal karyotypes have not been established. In this study, we successfully established primary and immortalized fibroblast cell lines through the combined expression of human-derived mutant cyclin-dependent kinase 4 (CDK4R24C), cyclin D1, and Telomerase Reverse Transcriptase (TERT), although CDK4R24C and cyclin D1, SV40T and TERT did not result in successful immortalization. Our comparison of the properties of these immortalized cells demonstrated that K4DT immortalized cells maintain a normal karyotype. Ultimately, our findings could pave the way for the development of targeted interventions to enhance the health and well-being of American miniature horses.

Computer-assisted surgery for placing toggle constructs across the coxofemoral joints of small equids using a minimally invasive approach-A proof-of-concept cadaveric study.

To develop a minimally invasive technique for placing a toggle construct across the coxofemoral joint of small equids using computer-assisted surgery. Experimental cadaveric study. Three pilot specimens: One donkey, one Shetland pony and one Warmblood foal. Six main study specimens: Three Shetland ponies, one American Miniature Horse, one Warmblood foal and one donkey. Experimental surgeries were performed on both coxofemoral joints of each cadaver. Using a minimally invasive surgical approach, 5.5 mm bone canals were drilled through the femur and acetabulum, traversing the coxofemoral joint. Intraoperative guidance was provided by a cone-beam computed tomography (CBCT)-coupled surgical navigation system. A toggle construct was introduced through the bone canals. Surgical accuracy aberrations (SAA) were measured at the femoral entry and exit points and at the acetabular entry point on merged pre- and postoperative CBCT scans. The coxofemoral joint was assessed for articular cartilage damage by gross dissection. A toggle construct was placed across all 18 coxofemoral joints. The overall median SAA in the main study was 2.8 mm (range: 0.4-8.0 mm). No cartilage damage was found in the cadaveric specimens of the main study. The described technique allowed for the placement of a toggle construct across the coxofemoral joint of small equid cadaveric specimens without prior coxofemoral luxation. This technique may serve as an option for surgical stabilization of coxofemoral joints in small equids. Further biomechanical investigations are required to assess optimal implant positioning and toggle constructs.

Exterior features of American miniature horses of the pony farm "Idalgo"

The main task of preserving populations of small breeds of horses imported from abroad with their unique characteristic features of the exterior and type of constitution is the organization of the reproduction of the livestock and the preservation of the exterior parameters of the breed in descendants. In modern conditions of a small number of populations of such breeds, the influence of the inbreeding depression factor increases, as well as the manifestation of recessive mutations and hereditary pathologies in the offspring.[8] On the one hand, this can form changes that are not typical for the breed: phenotype, measurements, body type of the animal's format; on the other hand, such features of breeding horses in the absence of a selection press and selection will lead to the formation of a population of horses of the breed type. Such breed types should be fixed by breed leaders and have a territorial localization; if this does not happen, then the livestock that does not meet the requirements of the breed may lose the status of purebred. [2][6] The study consisted in monitoring the indicators of measurements by generation to identify the dynamics of changes in the format of the horse population and their compliance with the breed standard of American miniature pony horses. The article presents the indicators of the main measurements of American miniature pony horses for a number of generations and carried out their comparative analysis, with the standard requirements of the corresponding measurements of the breed. The analysis showed the following dynamics: in height at the withers, the increase is 46.5%, in the oblique length of the body, the increase is 97.8%, in the distance from the withers to the tail, the increase was 103.5%, which characterizes a more intensive growth of the peripheral skeleton in the postembryonic period and the formation of an elongated format with age . While the angle of the shoulder, wrist and tarsus is less variable in the age aspect and depends on individual hereditary factors, and not on age. A number of recommendations have been developed for specialists of the club "IDALGO" on the selection of parental pairs for correction for compliance with the standard requirements for measuring indicators in offspring.

Post‐partum paralysis following dystocia in a miniature horse

SummaryAn approximately 5‐year‐old American Miniature Horse mare presented for dystocia of several hours’ duration. Upon arrival she was in sternal recumbency and unable to stand, with both pelvic limbs splayed perpendicular to her body. The mare was induced under general anaesthesia and a controlled vaginal delivery with partial fetotomy was performed. After resolution of the dystocia, the mare could not stand without support but was able to bear weight and ambulate with her hind legs hobbled. The mare was diagnosed with bilateral obturator neuropathy following radiographs to rule out orthopaedic injury. She was hobbled, confined for 24 h, and treated with corticosteroids, anti‐inflammatories and antibiotics. After 24 h, the mare could comfortably bear weight, and after 96 h she could walk without hobbles. She was discharged 6 days after admission with only mild lateral hindlimb instability.

Imaging of equine septic discospondylitis using MRI, CT and post‐mortem radiographs

SummaryThis report describes a case of septic discospondylitis in an 11‐year‐old American Miniature stallion. Key imaging features are described here and include Fast Spin Echo T2/STIR hyperintensity on MRI of the intervertebral disc space and surrounding soft tissues as well as vertebral endplate destruction. Spinal cord deformation was seen concurrently and is considered likely secondary to either associated inflammatory granulation tissue or disc herniation. These findings most likely explain the apparent cervical pain and spinal ataxia grade 2/5 due to cervical spinal cord disease in this case.

Identification of W13 in the American Miniature Horse and Shetland Pony Populations.

Coat color is a trait of economic significance in horses. Variants in seven genes have been documented to cause white patterning in horses. Of the 34 variants that have been identified in KIT proto-oncogene, receptor tyrosine kinase (KIT), 27 have only been reported in a single individual or family and thus not all are routinely offered for genetic testing. Therefore, to enable proper use of marker-assisted selection, determining breed specificity for these alleles is warranted. Screening 19 unregistered all-white Shetland ponies for 16 white patterning markers identified 14 individuals whose phenotype could not be explained by testing results. In evaluating other known dominant white variants, 14 horses were heterozygous for W13. W13 was previously only reported in two quarter horses and a family of Australian miniature horses. Genotyping known white spotting variants in 30 owner-reported white animals (25 Miniature Horses and five Shetland ponies) identified two additional W13/N American Miniature Horses. The estimated allele frequency of W13 in the American Miniature Horse was 0.0063 (79 N/N, 1 W13/N) and the allele was not detected in a random sample (n = 59) of Shetland ponies. No homozygous W13 individuals were identified and W13/N ponies had a similar all-white coat with pink skin phenotype, regardless of the other white spotting variants present, demonstrating that W13 results in a Mendelian inherited dominant white phenotype and homozygosity is likely lethal. These findings document the presence of W13 in the American Miniature Horse and Shetland pony populations at a low frequency and illustrate the importance of testing for this variant in additional breeds.

A retrospective multicenter study on the use of locking compression plates for scapulohumeral arthrodesis in small equids.

To report on technical aspects and outcomes after scapulohumeral arthrodesis (SHA) with a locking compression plate (LCP) in small equids. Retrospective multicenter case series. Client-owned Shetland Ponies, Miniature Shetlands, and American Miniature Horses (n=15). Inclusion criteria were completed SHA with an LCP to treat scapulohumeral osteoarthritis/subluxation and availability of postoperative radiographs. Contributing surgeons completed a questionnaire to collect data. All radiographs were reviewed for this study. Follow-up information was obtained via re-admission to the hospital or telephone interview of the referring veterinarian or owner. Outcome was subjectively scored as excellent, good, moderate, or poor based on lameness and function. Sixteen SHAs were performed in 15 equids (body weight 65-145 kg) by nine different surgeons. A narrow 4.5/5.0 mm LCP (7-16 holes) was used in 14 of the 16 SHAs. Follow-up was collected 2.5 years after surgery (median; range: 9 weeks to 10 years). Major complications related to the SHAs were noted in 4 of the 13 horses alive long term, consisting of implant failure (n=1), surgical site infection (n=2), and scapular fracture (n=1). The outcome was graded as excellent in 4, good in 5, and moderate in 4 horses. Two ponies were euthanized because scapulohumeral osteoarthritis and subluxation developed in the contralateral limb. Although major complications occurred in about one-third of ponies, SHA with LCP led to long-term survival with good function in most ponies. SHA with an LCP offers a high chance for good long-term outcome in small equids although contralateral disease may affect outcome.

Electrocardiographic Aspects of Singleton Pregnancy and Neonatal Period in American Miniature Horse Breed

Background: During pregnancy, cardiovascular adaptations occur in order to meet maternal demands and adequate support for fetal development, but they are still unclear in the equine species, especially in the American Miniature horse breed. The main hemodynamic changes that occur during pregnancy are increased heart rate, cardiac output, and blood volume. It is necessary to use the reference values for the miniature breeds, in addition to the age range and reproductive condition, so the objective of this study was to evaluate the effect of pregnancy on electrocardiographic (ECG) parameters in mares and also of age in newborns foals of American Miniature horse breed. Materials, Methods & Results: Ten American Miniature Horse mares, between 7 and 19 years old (12.14 ± 4.05 years), 116.85 ± 24.09 kg of body weight were used in the experiment. All these mares were pluriparous, with 5.9 ± 3.5 of births, minimum of 2, and maximum of 12 foaling times. They were maintained in common social group in an indoor house stable with straw bed, with access to an outdoor paddock for several h per day. Twice a day they were fed with hay. Mineral supplements and water were available ad libitum. The ECG were obtained in 10 pregnant mares and in 10 neonates. All females were examined at a representative time of each trimester of pregnancy, at 30, 210, 300 days before and 21 days after delivery. Neonates were examined on different times: first 24 h after delivery, weekly on the 7th, 14th, 21st, 28th and 35th days of age. The ECG parameters considered were the heart rate and rhythm, duration and intervals (P, PR, QRS, QT, T) and amplitude (P, R, S, T) of ECG waves. The mean of pregnancy duration was 319.4 ± 4.97 days. Heart Rate (HR) varied between 51 to 59 bpm during pregnancy and 56 bpm on the 21st day after delivery. Comparing the clinical parameters of pregnant mares, non-pregnant mares and foal a difference was found for HR, Respiration Rate (RR) and Temperature (P = 0.001). All ECG parameters of pregnant, non-pregnant and foal mares showed a significant difference (P = 0.0001), except for the amplitude of the P1, P2 and R waves, which was similar for the 3 groups. The mean values of HR and amplitude of the positive T wave were higher in foals when compared to pregnant and non-pregnant mares, which in turn did not differ from each other. The mean duration of the P wave, PR segment, QRS complex, QT segment and T wave were the same among mares and greater than in foals. Comparing pregnant and non-pregnant mares, there was a difference in only 3 parameters: duration of the QTc segment, amplitude of the S wave and negative T wave. The non-pregnant mares had a longer duration of the QTc segment and a greater amplitude of the negative T wave, while the foals had a greater amplitude of the S wave.Discussion: Although this study did not measure HR at delivery time, it is worth to consider the action of the parasympathetic autonomic nervous system close to delivery, which reduces the HR of mares. This is because at delivery, sympathetic-adrenal activation should be avoided since the increase in sympathetic tone can cause uterine atony via B2 receptors. For this reason, it has been shown that, during physiological birth, horses are under parasympathetic control, and stress response mechanisms are not activated. It was conclude that the morphometry of the waves, intervals and ECG complexes, during the evolution of the reproductive state, the electrocardiographic aspects were generally associated with heart rate (PR and QT intervals). As for neonates, there was a discrepancy among the most of ECG parameters when compared to the adult female, regardless of reproductive status, clarifying the importance of ECG patterns not only for the breed, but also for the age group.

Sequence analysis of the coding regions of the apolipoprotein C2 (APOC2) gene in Miniature Schnauzers with idiopathic hypertriglyceridemia

It has been hypothesized that idiopathic hypertriglyceridemia in Miniature Schnauzers is hereditary, but the gene responsible has yet to be identified. The objective of this study was to determine if there were coding variants in the apolipoprotein C2 (APOC2) gene in Miniature Schnauzers with idiopathic hypertriglyceridemia. Blood samples from 12 Miniature Schnauzers with idiopathic hypertriglyceridemia were analyzed. Genomic DNA was extracted from whole blood, and the three coding exons of APOC2 were amplified by PCR. The PCR amplicons were sequenced and analyzed for variants relative to the canine reference genome (CanFam3.1 assembly). A second objective was to determine the extent of variation in coding exons of APOC2 in a large and diverse canine population using the Dog Biomedical Variant Database Consortium variant catalog, comprised of whole genome sequencing variant calls from 582 dogs of 126 breeds and eight wolves. There were no variants detected in the coding exons of APOC2 for any of the 12 Miniature Schnauzers with idiopathic hypertriglyceridemia. Variants in the coding exons of APOC2 were also rare in the Dog Biomedical Variant Database Consortium variant catalog; a single synonymous variant was identified in a heterozygous state in a Tibetan Mastiff. Thus, we concluded that coding variants in APOC2 are unlikely to be a major cause of idiopathic hypertriglyceridemia in North American Miniature Schnauzers and furthermore, that such coding variants are rare in the canine population.

Whole genome detection of sequence and structural polymorphism in six diverse horses.

The domesticated horse has played a unique role in human history, serving not just as a source of animal protein, but also as a catalyst for long-distance migration and military conquest. As a result, the horse developed unique physiological adaptations to meet the demands of both their climatic environment and their relationship with man. Completed in 2009, the first domesticated horse reference genome assembly (EquCab 2.0) produced most of the publicly available genetic variations annotations in this species. Yet, there are around 400 geographically and physiologically diverse breeds of horse. To enrich the current collection of genetic variants in the horse, we sequenced whole genomes from six horses of six different breeds: an American Miniature, a Percheron, an Arabian, a Mangalarga Marchador, a Native Mongolian Chakouyi, and a Tennessee Walking Horse, and mapped them to EquCab3.0 genome. Aside from extreme contrasts in body size, these breeds originate from diverse global locations and each possess unique adaptive physiology. A total of 1.3 billion reads were generated for the six horses with coverage between 15x to 24x per horse. After applying rigorous filtration, we identified and functionally annotated 17,514,723 Single Nucleotide Polymorphisms (SNPs), and 1,923,693 Insertions/Deletions (INDELs), as well as an average of 1,540 Copy Number Variations (CNVs) and 3,321 Structural Variations (SVs) per horse. Our results revealed putative functional variants including genes associated with size variation like LCORL gene (found in all horses), ZFAT in the Arabian, American Miniature and Percheron horses and ANKRD1 in the Native Mongolian Chakouyi horse. We detected a copy number variation in the Latherin gene that may be the result of evolutionary selection impacting thermoregulation by sweating, an important component of athleticism and heat tolerance. The newly discovered variants were formatted into user-friendly browser tracks and will provide a foundational database for future studies of the genetic underpinnings of diverse phenotypes within the horse.

Radiographic tracheal lumen to vertebral ratios in the normal American Miniature Horse.

Tracheal collapse in horses is reportedly uncommon; however, American Miniature Horses are more commonly affected.There is no description of the tracheal luminal diameter of American Miniature Horses, making early detection of tracheal luminal narrowing difficult. To 1) describe radiographic tracheal luminal diameter in clinically normal American Miniature Horses, 2) report the prevalence of subclinical tracheal collapse in a population of American Miniature Horses, and 3) use tracheal videofluoroscopy to quantify variation in tracheal luminal diameter throughout the respiratory cycle in horses with no clinical respiratory disease. Descriptive observational reference interval study. Thirty-four American Miniature Horses with no reported history of respiratory illness were recruited. Lateral cervical and thoracic radiographs were obtained in unsedated standing horses. Dynamic fluoroscopic images were obtained of the cervical and thoracic trachea throughout the respiratory cycle. Horses were then sedated as needed and tracheoscopy was performed. Twenty-nine horses were categorised as normal, and five horses were categorised as subclinically affected based on 25% or greater tracheal narrowing using tracheoscopy for visual assessment. Radiographic tracheal lumen to vertebral body measurements were obtained throughout the cervical and thoracic trachea. Maximum and minimum fluoroscopic tracheal diameter at each site throughout the respiratory cycle was recorded. A mean, median, 95% confidence interval and bootstrapped 95% reference interval of radiographic tracheal diameter to vertebral body ratios were generated in normal horses. The prevalence of subclinical tracheal collapse inthis population of American MiniatureHorses is 14.7%. Bootstrapped reference range was generated from 29 horses. Radiographic tracheal measurements and ratios of the tracheal diameter to vertebral body in the normal American Miniature Horse are describedherein andcan be used as a guideline when screening for tracheal disease in American Miniature Horses. The prevalence of subclinical tracheal collapse in American Miniature Horses may be higher than previously reported.

Effects of Dietary Arginine Supplementation in Pregnant Mares on Maternal Metabolism and Foal Birthweight

Withers height is an important economic trait for the American Miniature Horses (AMHs) as the breeders' primary objective is to produce small and proportionate animals. Identification of Quantitative Trait Loci (QTLs) affecting height in this breed will result in a better understanding of the genetic architecture and biological pathways contributing to skeletal development. In earlier work, we genotyped 48 horses from 16 different breeds that represent extremes in body size, using the Equine SNP50 bead chip (Illumina Inc). In this study, we applied a dominant model Genome-wide association study (GWAS), a genome-wide fixation index (FST) estimation, as well as a cross-population composite likelihood ratio (XP-CLR) test between the eight large and eight small breeds from this data set. Our GWAS implicated the marker at ECA1:37,676,322 bp, positioned within an intron of the ANKRD1 gene, was significantly associated with height variation. An XP-CLR scan further supported a role in height for the ECA1:37,676,322 bp locus and the FST analysis supported correlations to IGF2BP2 at ECA19:23,815,750. To confirm our findings, we genotyped the candidate loci in an independent set of 89 AMHs. This set verified that the locus at ANKRD1 gene indeed correlates to height under a dominant mode of inheritance, but not the locus at the IGF2BP2 gene. ANKRD1, a transcription factor involved in myocyte growth and differentiation, may contribute to height by influencing the overall growth of the horses. This marker will be a valuable tool for the selection of breeding stock in breeds with height restrictions for registration.

Novel findings from a beta coronavirus outbreak on an American Miniature Horse breeding farm in upstate New York.

SummaryThis case report describes an outbreak and novel findings associated with a beta coronavirus (BCoV) infection that occurred on an American Miniature Horse (AMH) breeding farm in upstate New York, in January and February of 2013. Twenty‐nine AMH and one donkey were present on the farm when the outbreak occurred. One 10‐year‐old Quarter Horse mare, stabled at a separate location and owned by an employee of the farm, also tested positive. A polymerase chain reaction (PCR) assay for the detection of BCoV was performed at the Animal Health Diagnostic Center (AHDC) at Cornell on all faecal samples. The PCR assay used detects multiple beta coronaviruses, including, but not limited to, equine enteric coronavirus (ECoV). Novel findings regarding this BCoV infection in horses were recognised in this outbreak study. To the authors’ knowledge, this is the largest outbreak of BCoV described thus far in a closed herd on a single premise. The case fatality rate was 0% unlike that described in a previous outbreak of ECoV involving miniature horses and a miniature donkey (Fielding et al. 2015). The morbidity rate was lower in this outbreak than in previously described studies (Oue et al. 2013; Pusterla et al. 2013). This outbreak also demonstrated the potential for BCoV transmission via farm personnel. The duration of shedding of virus in the faeces among some asymptomatic horses in this outbreak was longer than previously described clinical cases of ECoV (Pusterla et al. 2013; Nemoto et al. 2014). This study suggests that asymptomatic animals may play a role in the maintenance of BCoV during an outbreak; therefore, the need for diagnostic testing of both clinically affected and apparently clinically normal horses on a premises followed by appropriate biosecurity and control measures.

Prevalence of the AMHR2 mutation in Miniature Schnauzers and genetic investigation of a Belgian Malinois with persistent Müllerian duct syndrome.

Persistent Müllerian duct syndrome (PMDS) is a sex-limited disorder in which males develop portions of the female reproductive tract. Important consequences of PMDS are cryptorchidism and its sequelae of infertility and increased risk of testicular cancer. Anti-Müllerian hormone (AMH) and its receptor (AMHR2) induce the regression of the Müllerian ducts in male embryos. In Miniature Schnauzer dogs, the genetic basis has been identified as an autosomal recessive nonsense mutation in AMHR2, but the allele frequency of the mutation is unknown. Thus, the primary objective of this study was to estimate the prevalence of the AMHR2 mutation in North American Miniature Schnauzers, in order to ascertain the value of genetic testing in this breed. An additional objective was to determine whether mutations in AMH or AMHR2 were responsible for PMDS in a Belgian Malinois; this would aid development of a genetic test for the Belgian Malinois breed. Genomic DNA from 216 Miniature Schnauzers (including one known PMDS case) was genotyped for the AMHR2 mutation, and DNA from a single PMDS-affected Belgian Malinois was sequenced for all coding exons of AMH and AMHR2. The Miniature Schnauzer cohort had an AMHR2 mutation allele frequency of 0.16 and a carrier genotypic frequency of 0.27. The genetic basis for PMDS in the Belgian Malinois was not determined, as no coding or splicing mutations were identified in either AMH or AMHR2. These findings support a benefit to AMHR2 mutation testing Miniature Schnauzers used for breeding or with cryptorchidism.

Genome-Wide Scans Reveal a Quantitative Trait Locus for Withers Height in Horses Near the ANKRD1 Gene

Withers height is an important economic trait for the American Miniature Horses (AMHs) as the breeders' primary objective is to produce small and proportionate animals. Identification of Quantitative Trait Loci (QTLs) affecting height in this breed will result in a better understanding of the genetic architecture and biological pathways contributing to skeletal development. In earlier work, we genotyped 48 horses from 16 different breeds that represent extremes in body size, using the Equine SNP50 bead chip (Illumina Inc). In this study, we applied a dominant model Genome-wide association study (GWAS), a genome-wide fixation index (FST) estimation, as well as a cross-population composite likelihood ratio (XP-CLR) test between the eight large and eight small breeds from this data set. Our GWAS implicated the marker at ECA1:37,676,322 bp, positioned within an intron of the ANKRD1 gene, was significantly associated with height variation. An XP-CLR scan further supported a role in height for the ECA1:37,676,322 bp locus and the FST analysis supported correlations to IGF2BP2 at ECA19:23,815,750. To confirm our findings, we genotyped the candidate loci in an independent set of 89 AMHs. This set verified that the locus at ANKRD1 gene indeed correlates to height under a dominant mode of inheritance, but not the locus at the IGF2BP2 gene. ANKRD1, a transcription factor involved in myocyte growth and differentiation, may contribute to height by influencing the overall growth of the horses. This marker will be a valuable tool for the selection of breeding stock in breeds with height restrictions for registration.

Effect of pregnancy and correlation of weight and heart rate with electrocardiographic parameters in the American Miniature Horse

ABSTRACT There are studies on electrocardiogram (ECG) in several breeds of horses, which highlights the growing importance of cardiology in this species. But few authors have addressed the influence of pregnancy on the cardiac physiology of the mare, and specifically, there are no studies on the Mini-horse breed, as well as no correlation of body weight (BW) and heart rate (HR) with electrocardiographic parameters in this breed. The aims of this study were to determine the effects of pregnancy on ECG parameters and to examine the relationships between these variables and body weight (BW) and heart rate (HR). A total of 203 animals were used, including 143 females (66 pregnant) and 60 males. Electrocardiographic examinations were performed by computerized electrocardiogram (TEB), and the parameters were evaluated in six leads in the frontal plane (Lead I, II, III, aVR, aVL and aVF) and base-apex (BA). BW was inversely proportional to HR, which in turn showed an inverse relationship with the duration of the P-wave and the PR and QT intervals. The P-wave amplitude (lead II) was higher in pregnant animals than in non-pregnant animals. The effect of reproductive status should be monitored by ECG throughout the entire gestational period. The 66 pregnant mares in this study were examined during the first third of their pregnancies, thus, few differences were observed between pregnant and non-pregnant animals.

Electrocardiographic parameters of the American Miniature Horse: influence of age and sex

Abstract: The veterinary cardiology has growing importance in equine medicine. There are studies of standardization of electrocardiographic parameters of many races, according to their stature and ability. However, no studies are in the literature with the American Miniature Horse. To evaluate the electrocardiogram (ECG) tracing configuration of this breed at rest and to verify the influence of age and sex on ECG parameters, 203 horses including 143 females and 60 males were divided into four age groups (foals, yearlings, adults and elderly). Electrocardiographic parameters were performed by computerized electrocardiogram (TEB), and the parameters were evaluated in six leads of frontal plane (Lead I, II, III, aVR, aVL and aVF) and base-apex (BA). Heart rates (HR) decreased with increasing age were higher in males than in females. Sinus tachycardia followed by sinus arrhythmia was dominant in both sexes. The cardiac axis was higher in males and ranged between 120° and 150° for foals, 30° and 60° for yearlings and adults, and 60° and 90° for the elderly. The P wave was bifid in several animals. The P-wave amplitude and T-wave duration from lead II and BA were larger in males than in females. The majority of the animals exhibited ST segment depression and a negative T-wave. The most common QRS complex morphology was Qr. Differences were observed between the electrocardiographic tracings of males and females, and age influenced the ECG parameters. Therefore, this study established the ECG patterns for the American Miniature Horse breed and could be used to determine the influence of age and sex on several of the studied variables.

Surgical management of an extrahepatic portosystemic shunt in a foal: A multidisciplinary problem

SummaryA 5‐week‐old American Miniature filly was referred due to intermittent neurological signs of 4 weeks' duration. Clinicopathological findings showed increased ammonia and bile acids in venous blood samples. Abdominal ultrasonography detailed a portosystemic shunt (PSS). The foal underwent laparotomy and operative mesenteric portovenography, which further defined the PSS as extrahepatic portocaval in configuration. The PSS was occluded and intraoperative portovenography confirmed successful shunt occlusion. The foal made a good recovery from surgery and had a successful showing career until she succumbed to colic just over 3 years after surgery.

Reference values for amino acids and acylcarnitines in peripheral blood in Quarter horses and American Miniature horses.

BackgroundFree amino acids and acylcarnitines circulating in the blood can be used for diagnosis for metabolic illness and imbalances. To date, the normal reference ranges of amino acids and acylcarnitines in horse peripheral blood have not been established. In this study, the concentrations of 12 amino acids and 26 acylcarnitines were determined by tandem mass spectrometry in complete blood from 100 healthy horses (50 Quarter horses (QH) [23 males and 27 females] and 50 American Miniature horses (AMH) [15 males and 35 females]) with no signs of metabolic disease. The means and standard deviations were determined and data statistically analyzed.FindingsConcentrations of short, medium, and long chain acylcarnitines were significantly higher in male AMH than in male QH. The concentrations of the amino acids alanine, arginine, glycine, proline (glycogenic), and leucine (ketogenic) were higher in the QH than in the AMH. Female AMH had higher concentrations of propionylcarnitine, leucine, proline, arginine, and ornithine than female QH.ConclusionsNormal reference ranges of amino acids and acylcarnitines were established for AMH and QH. Significant differences were found in concentration of these compounds between breeds and gender.Electronic supplementary materialThe online version of this article (doi:10.1186/s13028-015-0144-9) contains supplementary material, which is available to authorized users.

Métodos eletrocardiográficos em equinos American Miniature Horse

O objetivo deste estudo foi analisar e comparar os registros eletrocardiográficos de 50 equinos American Miniature Horse, clinicamente saudáveis, obtidos pelos métodos convencional e computadorizado, para a padronização do método informatizado. As medidas de duração e amplitude das ondas e intervalos e frequência cardíaca foram analisadas nas derivações do plano frontal e na derivação base-ápice. Diferenças quanto à duração da onda P, foram encontradas nas derivações I e aVL, e do complexo QRS, em todas as derivações do plano frontal. Quanto à derivação base-ápice, houve diferença na duração do intervalo QT e da onda T, assim como na amplitude da onda S. Concluiu-se, portanto, que ocorre superestimação da duração do complexo QRS no método computadorizado e que, devido às diferenças inerentes de cada método, torna-se importante a utilização de valores de referência para o método computadorizado também na espécie equina