Search Results (10)

Background: In horses, standing arthroscopy offers a valuable alternative to general anesthesia for the reduction of anesthetic-associated risks, and provides improved visualization in joints where access is facilitated by weightbearing. These techniques are particularly advantageous for patients with increased anesthetic risk or financial limitations. To the authors’ knowledge, the removal of osteochondral fragments from the distal interphalangeal joint in a standing, sedated horse using small-diameter arthroscopic equipment has not been previously reported. Case Presentation: A 7-year-old American Quarter Horse–Thoroughbred cross presented on referral for treatment of osteochondral fragmentation in the right fore distal interphalangeal joint. A standing arthroscopic approach to the distal interphalangeal joint was performed. In a weight-bearing position, debridement of the dorsal osteochondral fragments from the second and third phalanx was successfully completed, using a 2 mm NanoNeedle scope and 3.2 mm high-flow 10- degree cannula (Arthrex^®). At one year follow-up, the horse had returned to competition and was sound at veterinary examination. Conclusion: This case demonstrates the feasibility of standing NanoNeedle arthroscopy of the equine coffin joint with improved maneuverability, surgical ergonomics, and reduced iatrogenic injury compared to a standard rigid arthroscope. The successful execution of this technique effectively expands our collection of standing arthroscopic procedures in the equine patient. Full article

This study aimed to generate information for parentage testing in horse breeds using microsatellites (STRs) and single-nucleotide polymorphisms (SNPs). Genotype data were obtained from 189 horse hair root samples, including 38 Thoroughbreds (TBs), 17 Jeju horses (JHs), 20 Quarter horses (QHs), 21 American Miniatures (AMs), and 93 Mongolian horses (MHs), using 15 STR markers and 71 SNP markers. Comparative analysis revealed that the mean expected heterozygosity ranged from 0.468 (AM) to 0.491 (JH) for SNPs and from 0.695 (TB) to 0.791 (MH) for STRs. The mean observed heterozygosity ranged from 0.415 (AM) to 0.487 (MH) for SNPs and from 0.706 (JH) to 0.776 (MH) for STRs. The mean polymorphic information content ranged from 0.349 (AM) to 0.364 (MH) for SNPs and from 0.635 (TB) to 0.761 (MH) for STRs. The inbreeding coefficient ranged from −0.009 (MH) to 0.113 (AM) for SNPs and from −0.058 (TB) to 0.043 (AM) for STRs. The cumulative exclusion probability (PE) for the 71-SNP panel exceeded 0.9999, indicating that SNP markers may be sufficient for parentage testing. In comparison, the STR markers yielded a combined PE of 0.9988 when one parent was known and 0.9999 when both parents were known. These findings highlight the potential of SNPs as alternatives to STRs for routine paternity verification in horses. Full article

Roan coat color is described as the dispersion of white hairs within an otherwise solid background-color coat. This phenotype is primarily expressed on the body of the horse, with the head and legs exhibiting few or no white hairs. Previous studies mapped the locus for roan to the KIT region and observed linked variants in a small number of breeds. Recently, we reported evidence for two independent haplotypes, RN1 and RN2, in the KIT region, which account for approximately 38% and 36% of roan horses, respectively. In the current report, using whole genome sequencing for unknown roan samples. We present a third novel haplotype, RN3, found in American Quarter Horses, that accounts for an additional 30% of American Quarter Horses negative for RN1 and RN2 that display the roan phenotype. Within this haplotype, we observe a variant chr3:79656505 (G > A), which we believe is a founder allele for the RN3 haplotype. In our sample set of horses, these three haplotypes account for more than 95% of the American Quarter Horse population studied and about 50–60% of roan horses in other breeds. Using whole genome sequencing of distantly related animals with a particular phenotype, together with a larger number of control horses, improves the odds of finding linked and/or causative variants. Full article

The roan coat color is described as the dispersion of white hairs within an otherwise solid background color coat. This phenotype is primarily expressed on the body of the horse, with the head and legs exhibiting few to no white hairs. Previous studies mapped the locus for roan to the KIT region and observed linked variants in a small number of breeds. However, utilizing those linked markers to determine the roan genotype in other breeds has seen limited success. In this communication we identify a second roan allele (RN2) which, in conjunction with a previously observed roan allele (RN1) discovered in previous studies, accounts for approximately 74%, or 188 horses, out of a sample size totaling 257 roan horses. These two alleles were present in the non-roan population (N = 3212) at less than 1%, only in horses with light coat color and dilution alleles, likely obscuring the roan phenotype. Future work is required to identify additional alleles responsible for additional roan-type horse coat color phenotypic variation. Full article

Overtraining syndrome (OTS) is the reduction in performance due to excess training and lack of proper recovery, which can lead to a chronic deprivation of energy and reduction in the repair of damage that can accumulate over time. Here, the effect of acute, intense physical exercise on the expression of innate and adaptive immune genes in 12 racing-bred American Quarter Horses, after resting for 3 days and immediately after intense exercise for 1.8 miles were compared. The expression of 84 genes related to innate and adaptive immune responses was analyzed. Significant variation among individuals and between sexes was observed. The analysis showed that five genes were differentially expressed in both females and males, three only in females, and two in males. The upregulated genes were IL13 (male only), CCR4 (female only), TLR6, TLR9 (female only), NFKBIA, CXCR3, and TLR4, while the downregulated genes were IL6 (female only), CD4 (male only), and MYD88. The three main pathways containing genes that were affected by acute, intense physical exercise were Th1 and Th2 cell differentiation, and the NF-kappa B and chemokine signaling pathways, suggesting the activation of the proinflammatory responses as a result of the stress from the acute exercise. Gene expression could be used to assess indications of OTS. Full article

The term “Western Message Petroglyphs” (WMPs) refers to a number of petroglyph sites found scattered among eight western states that are recognized by their shared image content and layout. The imagery is drawn largely from a mash-up of late historic Native American sign-gesture language and picture-writing traditions inter-mixed with pan-cultural imagery from around the world. An increasing number of sites that fit this mold have been reported over the past 85 years or so, currently numbering 39 in all. There is no question that these sites date to post-European contact based on images in some panels that depict Euro-American cultural content (e.g., western-style house, rifle, whiskey keg, horse, etc.). The post-contact era is also apparent in the method used in rendering the engraved images evidenced by the smooth angular lines and chisel strikes produced by metal tools. This paper focuses on narrowing the time frame for these sites based on two additional streams of evidence. First, patterned associations with historic landscape settings tied to the era of western expansion bind the sites together into a coherent whole and set a floor for their oldest probable dates. An example of four sites located in Utah and Arizona illustrates their connection to the last quarter of the nineteenth century and the opening years of the twentieth. Secondly, a study of their imagery supports the proposed dates by revealing a “smoking gun” for the source of many of the individual icons. An example of the methodology used to translate a Western Message Petroglyph panel is described, and a profile of the central author who appears to have acted with a small group of others is suggested in order to aid in the search for this person(s) in the historic record of the American West. Full article

Over 40 identified genetic variants contribute to white spotting in the horse. White markings and spotting are under selection for their impact on the economic value of an equine, yet many phenotypes have an unknown genetic basis. Previous studies also demonstrate an interaction between MC1R and ASIP pigmentation loci and white spotting associated with KIT and MITF. We investigated two stallions presenting with a white spotting phenotype of unknown cause. Exon sequencing of the KIT and MITF candidate genes identified a missense variant in KIT (rs1140732842, NC_009146.3:g.79566881T>C, p.T391A) predicted by SIFT and PROVEAN as not tolerated/deleterious. Three independent observers generated an Average Grade of White (AGW) phenotype score for 147 individuals based on photographs. The KIT variant demonstrates a significant QTL association to AGW (p = 3.3 × 10⁻¹²). Association with the MC1R Extension locus demonstrated that, although not in LD, MC1R e/e (chestnut) individuals had higher AGW scores than MC1R E/- individuals (p = 3.09 × 10⁻¹⁷). We also report complete linkage of the previously reported KIT W19 allele to this missense variant. We propose to term this variant W34, following the standardized nomenclature for white spotting variants within the equine KIT gene, and report its epistatic interaction with MC1R. Full article

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. Full article

To investigate differences in American Quarter Horses conformation suggesting specialization and subpopulations within the breed, a total of 45 horses were studied. These horses were classified according to their specific sport discipline: Western Pleasure (WPL, n = 15), Hunter under Saddle (HUS, n = 15), and Reining (RN, n = 15). Fifteen linear traits (comprising lengths, angles, and circumferences) were measured analogically and photometrically. Afterwards, 9 ratios and differences were calculated, so that a total of 24 traits were examined. The results showed significant differences between horses depending on their sport discipline. HUS horses were significant taller and were characterized by higher values in (nearly) all length traits; they were followed by WPL and RN horses. RN horses displayed the lowest values in length traits but the largest difference between height at withers and height at croup. Nine parameters were analyzed through correlations to the height at withers; all differences were significant, with high to moderate correlation coefficients. The detected differences between the groups support recent studies on the conformation and genotype of subpopulations within a breed and reveal new findings in relation to the selected disciplines. Image analysis worked well and provided reliable data; therefore, this method can be used to examine horses in a time-efficient manner, reducing the stress caused to the animal. Further studies are required to gain more information and to associate the features of AQH anatomic structures with successful performance. Full article

It is dangerous for both riders and horses when a horse suddenly startles. Sometimes horses do this in familiar environments because familiar objects may look different when rotated. The purpose of this study was to determine whether horses that had been habituated to a complex object (children’s playset) would react to the object as novel when rotated 90 degrees. Twenty young horses were led past the playset 15 times by a handler. Next, the rotated group was led past the rotated playset 15 times. Each time the horse was led by the object was a pass. The behavioral responses observed and analyzed were ears focused on the object, nostril flares, neck raising, snort, avoid by stopping, avoid by moving feet sideways, and avoid by flight. An increasing reactivity scale was used to quantify behavioral responses. A two-sample t-test was performed on the reactivity scores comparing the first pass by the novel object to the first pass by the rotated object. The horses in the rotated group reacted to the rotated orientation similarly to the first exposure (p = 0.001, α < 0.05). Being aware of potential reactions to changes in previously familiar environments can help keep the handler safer. Full article