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• Horse face shape is a continuous trait; categorized into dished, straight and roman • Geometric morphometrics can quantitatively phenotype horse face profiles • Over 70 % of horse breeds exhibit straight face profile • Arabian horses possessed the highest diversity in face profile • The face profile phenotype can be the basis of future genetic association studies Horse traits under selection are largely quantitative and affected by multiple genes. Horse face shape is an example of a continuous trait, which due to the reliance on observational assessments, is classified into; "dished", "straight", and "roman-nosed". This categorization is often inadequate to convey the full spectrum of the face shape variation especially for genetic studies. The first objective of the current study was to use geometric morphometric methods to quantitatively phenotype face shapes and examine its variation across horse breeds. The second objective was to analyze the face shape variation within Arabian horses since face shape is (1) favored, valued, and genetically selected in certain lineages (e.g. Egyptian), (2) is evaluated by registries and scored in shows, and (3) in its extreme forms pose health concerns. We digitized landmarks on lateral profile photos, particularly on the dorsal curvature of the rostrum, and subjected these landmarks to Generalized Procrustes Analysis to generate independent shape and size variables which were statistically compared across breeds and within Arabians. Horse breeds varied in nasal curvature, ranging from extremely concave to extremely convex, with over 70 % of horse breeds exhibiting intermediate concavity (i.e., straight profile). Interestingly, Arabian horses possessed the highest diversity in face profile and individuals clustered into three distinct shape sub-groups (one dished and two straight profile clusters). Our quantitative phenotyping method can be the basis of future genetic studies of facial profile within Arabian lineages as a favored traits and potentially manage its extreme forms as a likely genetic disease. [ABSTRACT FROM AUTHOR]

The aim of this study was to assay changes in blood biochemical parameters that resulted from exercise-induced muscle fatigue in horses participating in the two races (1,250 and 1,400 meters). Six male Arabian horses (3 to 6 years old) were used in this study. Blood samples were collected at time intervals including 1 hour before the race, immediately after the race, 1 and 24 hours after the end of race. Catalase (CAT), superoxide dismutase, glutathione peroxidase (GPX) activities, the blood level of malondialdehyde, protein carbonyl, and total antioxidant capacity (TAC) were measured, as well as muscle damage biomarkers including aspartate aminotransferase (AST), lactate dehydrogenase (LDH), creatine kinase (CK) activities, and myoglobin were measured. The results showed that CAT activity and plasma TAC in the horse increased immediately after the race and then gradually decreased. The highest GPX activity in red blood cells was recorded 1 hour before the start of the race. Superoxide dismutase showed an incremental pattern after the race. Immediately after the race, there was a significant increase in the plasma levels of AST, which continued until 1 hour after the race. The activity of LDH and CK reached its highest value 1 hour after the race. According to our findings, it can be concluded that the horses were tired and antioxidant enzymes altered under fatigue conditions. Muscle damage biomarkers have increased, but these increases were in their natural ranges and did not indicate muscle damage in horses. • Muscle fatigue and injury were evaluated simultaneously during two distances in speed race. • The distances used in this study cannot induce muscle injury in Arabian horses. • Antioxidant status was not affected by speed race in Arabian horses. [ABSTRACT FROM AUTHOR]

The Arabian horse breed is well known for its purity and played a key role in the genetic improvement of other horses worldwide. The mitochondrial genome plays a vital role in maternal inheritance and it's helpful to evaluate its genetic diversity and conservation. It has higher mutation rates than nuclear DNA in vertebrates and therefore reveals phylogenetic relationships and haplotypes. In this study, the mitochondrial genome mutations in two Saudi horse strains, Kehilan and Hamdani demonstrated various changes in the gene and amino acid levels and included two other Saudi horses (Hadban and Seglawi) from the previous study for phylogenetic comparison. The whole mitochondrial genome sequencing resulted in intra and inter mtDNA variations between the studied horses. Interestingly, the Hamdani horse has nucleotide substitutions similar to those of the Hadban horse, which is reflected in the phylogenetic tree as a significantly close relationship. This type of study provides a better understanding of mitogenome structure and conservation of livestock species genetic data. [ABSTRACT FROM AUTHOR]

Arabian horses, the eldest equine breeds, have great economic and social significance for its long, unique, and storied history. Molecular characterization of dermatophyte species affecting Arabian horses is a crucial necessity for epidemiologic and therapeutic purposes. The objective of this study was to identify and differentiate isolates of dermatophytes isolated from naturally infected Arabian horses at species and strains levels using PCR-restriction fragment length polymorphism (RFLP) and DNA sequencing. Additionally, antifungal susceptibility testing using broth microdilution method was performed for the isolated dermatophyte species against six antifungal agents. Dermatophytes isolates (n = 20) representing four different species including Microsporum ( M ) canis , M. equinum , Trichophyton ( T ) mentagrophytes , and T. verrucosum were subjected for molecular characterization. The isolated dermatophytes were identified based on PCR of the ribosomal region spanning internal transcribed spacer (ITS1 and ITS2), the 5.8S rDNA and subsequent restriction analysis using Mva I and sequence analysis. Trichophyton mentagrophytes and T. verrucosum were differentiated by PCR-RFLP; meanwhile, the restriction profile of M. canis was identical to that of Arthroderma otae (telomorphic state) and M. equinum . Internal transcribed spacer sequencing technique affirmed the RFLP findings and differentiated the closely related taxon. Itraconazole is effective against M. canis and M. equinum, while terbinafine and griseofulvin are more effective against T. mentagrophytes and T. verrucosum . In conclusion, PCR-RFLP technique is a reliable tool for the identification of dermatophyte species from Arabian horses. Internal transcribed spacer sequencing provides a precise and useful technique for the identification and differentiation of closely related dermatophyte species. Terbinafine, griseofulvin, and itraconazole are effective antifungals in the treatment of Arabian horse ringworm. [ABSTRACT FROM AUTHOR]

• The judges used small range of available scores. The scoring showed low variability between horses. • The correlation with the total score was the strongest for the score for type, and the weakest for the score for legs. • Head and neck had strong effect on the score for type. The effects of remaining categories were negligible or insignificant. • For yearling and junior classes, we observed no relationship between the score for legs and the score for movement. In senior classes this correlation was weak. • The relationships between scores varied within sex and age classes. Arabian show horses are well known for their exceptional beauty and elegance. The breed type, body conformation and movement are assessed during horse shows by licensed judges. The 5 judging categories are type, head and neck, body and topline, legs and movement, which are scored on a 20 point scale. It can be hypothesized that the scores in different categories are related to each other, and that the score for the most subjective type category depends on the scores for conformation categories. We analyzed 762 sets of average scores obtained by 583 unique horses at the World Championships. Correlation analysis and general linear models were used to explore the relationships between the scores in each of the 5 categories. Despite the 20 point scale, only scores from 14.5 to 20 were observed. The correlations between the total score, and the scores for each category within the whole sample varied from r = 0.413 for legs to r = 0.907 for type. Regression analysis of the scores for type showed a strong, significant (P <.001) effect of the scores for the head and neck. The effect of scores for body and topline as well as for movement was negligible, while significant; the score for legs did not affect the score for type. The correlation values between score categories varied between sex and age classes. The estimated levels of correlations were different than expected, based on the known relationships between the phenotypic traits. [ABSTRACT FROM AUTHOR]

The objective of the present study was to verify the prevalence and the risk factors associated with dermatophytosis in Arabian horses. For this purpose, a total of 457 Arabian horses in 15 farms were examined. A questionnaire was constructed to include the hypothesized risk factors. Fungal isolation and identification for each horse were carried out by standard microbiological procedures. Logistic regression analysis was used to evaluate the risk factors on both animal and farm levels. Trichophyton spp. was recovered from 50 horses and Microsporum spp. from 27 cases. Trichophyton equinum was more prevalent than Trichophyton mentagrophytes (45 vs. 4) and Trichophyton tonsurans (45 vs. 1). However, Microsporum canis was more prevalent than Microsporum gypseum (21 vs. 5) and Microsporum audouinii (21 vs. 1). On horse level, final multivariate logistic regression analysis showed that there was a significant association between dermatophytosis and horse' age ( P < .05; odds ratio [OR]: 1.07; 95% confidence interval [CI]: 1.0–2.69), poor grooming practice ( P < .05; OR: 57.11; 95% CI: 2.47–13.44), moist condition ( P < .05; OR: 42.77; 95% CI: 2.0–25.18), and farm size ( P < .05; OR: 1.06; 95% CI: 1.00–7.05). However, on the farm level, farm size of >30 horses was the risk factor ( P < .05; OR: 1.0; 95% CI: 1–3.03). In conclusion, the present results indicate existance of dermatophytosis in Arabian horses. Identification of the potential risk factors associated with the disease may be helpful to construct the ideal preventive measures. [ABSTRACT FROM AUTHOR]

One hundred ninety ejaculates were collected from 16 healthy Arab stallions (5–18 years; 12 normal and four slow breeders) over 12 months, and sexual behavior parameters were recorded. Serum samples were collected from stallions for determination of testosterone, estradiol-17β, cortisol, and glucose. The results revealed that the time to first mount, latency to erection, latency to mount, and number of mounts per ejaculate were significantly ( P < .001) shorter in normal breeders (61.12 ± 5.18, 49.45 ± 3.78, 82.54 ± 6.39, and 1.32 ± 0.04, respectively; n = 12) than in slow breeder stallions (259.82 ± 42.66, 228.26 ± 50.48, 371.95 ± 36.27, and 2.63 ± 0.35, respectively; n = 4). Sexual behavior abnormalities constituted 10.42% of all trials. Season exerted a significant ( P < .05) effect on all sexual behavior parameters except latency to ejaculation, which was the shortest during spring in the normal breeders. Sexual behavior abnormalities were significantly ( P < .05; 37%) higher in all stallions during autumn. Both serum estradiol-17β and cortisol levels rose significantly ( P < .05) after semen collection in all stallions. Serum estradiol-17β level was significantly ( P < .05) increased during spring and summer in all stallions. Cortisol levels were significantly ( P < .05) higher during autumn in both normal and slow breeder stallions (2,121.15 ± 115.55 and 69.37 ± 21.84 pg/mL, respectively). In conclusion, sexual behavior parameters in normal breeders were shorter in duration than that recorded in slow breeder stallions. Season affects sexual behavior parameters and serum estradiol-17β levels, with the highest values found during spring and summer. Estradiol-17β and cortisol were the two hormones responsible for sexual behavior in stallions. The best sexual behavior was accompanied by low levels of serum testosterone. [ABSTRACT FROM AUTHOR]

One hundred eighty ejaculates were collected from 15 healthy Arabian horses (6–26 years old) for morphometric evaluation of their spermatozoal dimensions. The progressively motile sperm percentage, sperm abnormalities percentage, and sperm cell concentration (×10 6 sperm/mL) were determined. Stained slides with nigrosin–eosin solution were prepared for sperm morphometric analysis using an eye-piece micrometer. The sperm measurements were sperm head length, head maximum breadth, head base breadth, acrosome length, midpiece and breadth, tail length and breadth, sperm head area, and perimeter. Data were divided according to season, stallions' age, and fertility. Results revealed that mensuration of sperm head length, head maximum breadth, midpiece length, and tail length were 5.96 ± 0.004, 3.06 ± 0.004, 10.17 ± 0.008, and 48.88 ± 0.022 μm, respectively. The head area and perimeter were 14.33 ± 0.022 μm 2 and 14.16 ± 0.009 μm, respectively. The total number of sperm per ejaculate in spring and summer was significantly ( P < .05) higher than in autumn and winter. The lowest sperm concentration (153.61 ± 26.75 × 10 6 /mL) and the longest head length (6.00 ± 0.01 μm) were found during winter. Sperm head length, head maximum breadth, head base breadth, head area, and perimeter were the lowest in group A (<10 years). Sperm morphometry was highly significantly ( P < .001) affected by the stallion. The head maximum breadth, head base breadth, sperm head area, and perimeter were ( P < .001) smaller in stallions with high fertility (69%–79%) compared with those of low fertility (50%–59%). In conclusion, stallion sperm morphometry was affected by the season, stallions' age, and stallions. Sperm head maximum breadth, head area, and perimeter were smaller in stallions of high fertilizing capacity. [ABSTRACT FROM AUTHOR]

Abstract: The aim of this study was to estimate the genetic parameters for racing performance of purebred Arabian horses in Poland. The traits used were coefficients of success (CS) and of running intensity (CI). The data included annually summarized race records of three- and four-year old Arabian horses being performance tested at the Polish racing tracks during the years 1946–1992. Coefficients for three- (CS3, CI3) and four-year olds (CS4, CI4) were analysed separately. The racing results were available for 2590 horses descending from 172 sires and 736 dams. Variance components estimation using REML method and VCE software gave the following values for heritability: 0.07, 0.09, 0.41, 0.18 for CI3, CI4, CS3 and CS4, respectively. The highest genetic correlations were obtained between CS3 and CS4 (0.9) as well as between CI3 and CI4 (0.7). There were no genetic relationships between CS3 and CI4 (r g =−0.06). Genetic correlation between CS3 and CI3 was 0.45 and between CI3 and CS4 was 0.19. The opposite signs of genetic and phenotypic correlations (−0.42 vs 0.44, respectively) between earnings and starting frequency for four-year-olds were observed. The correlations of observed breeding values of sires and dams (expressed as averages of the adequate coefficients achieved by a horse''s progeny as three- or four-year-olds) and estimated breeding values (BLUP-EBV''s) for CI and CS varied from 0.34 to 0.82. These correlations tended to decrease with decreasing estimates of heritability. The restriction of ten or five progeny in sire and dam analysis, respectively, increases the correlations, with the exception of CI4 for sires. [Copyright &y& Elsevier]

Abstract: Arabian horses are widely believed to be one of the oldest breeds in the world. There are many legends regarding their origin, some of which date back even to the times of King Solomon. The present study attempts to determine the real origin of the breed through the analysis of mtDNA sequences from American and Polish Arabs that are deposited in GenBank. The findings show that the origin of the breed is heterogeneous and that the diversity among particular sequences grouped into ten haplogroups is significant. A set of identical and similar sequences was found by comparing Arabian sequences to those from archaeological samples and present-day horses representing different breeds. These results permit formulating the hypothesis that the Arabian horse breed was created from many different breeds and populations, and the concept of breed purity, might refer, at most, to the present population with a history that does not exceed two hundred years. [Copyright &y& Elsevier]

The genetic structure of Polish Arabian horses over 50 years of breeding was studied based on founder contribution analysis. Data from 1032 brood mares and 154 sires in national studs, between 1948 and 1997, were analysed. Postwar Arabs are descended from 213 founders. During 50 years of breeding, there were increases in both the average number of founders in one pedigree (from 67.19 to 158.87) and in the proportion of the founders appearing in every pedigree (from 0% to 38.4%). The increase in mean kinship and inbreeding coefficient were also found. These results may be recognised as evidence of a reduction in genetic diversity of Polish Arabian horses. [Copyright &y& Elsevier]

• Differences in level of LD were found between breeds representing different horse types. • Breeds representing the same horse type showed similar trends of historical N e. • Longer haplotype block structure was found in Arabian breed than in native horse breeds. • Population history and breeding schemes may influence patterns of LD. This study was conducted to investigate linkage disequilibrium (LD), historical effective population size (N e) and haplotype block structures in genomes of highly selected Polish Arabian (AR; n=124) horses and conserved horse breeds derived from Polish native breeds, in particular, Malopolski (MLP; n=56), Sokolski (SOK; n=107), Sztumski (SZTUM; n=69), Hucul (HC; n=116) and Polish Konik (KN; n=99) horses, based on single nucleotide polymorphisms (SNPs) from the Neogen Equine Community BeadChip assay (Illumina, San Diego, CA). LD analysis was performed based on the pairwise r2 statistic of SNPs at a distance up to 5Mb. At a short distance, up to 100kb, the lower average r2 was observed in SOK (0.09) and SZTUM (0.10) breeds, representing draft horse type, and the highest average r2 was observed in AR (0.19) and MLP (0.17) breeds, representing light horse type. At a distance of 4-5Mb, the average values of r2 were 0.03 for HC and KN, 0.02 for AR and MLP and 0.01 for SOK and SZTUM. About 100 generations ago, effective population size (N e) ranged from 518 (SOK) to 310 (AR) and five generations ago from 85 (SOK) to 40 (HC). A total of 6,162 (AR), 5,792 (MLP), 5,744 (HC), 5,429 (KN), 5,542 (SOK) and 4,848 (SZTUM) haplotype block structures, spanning 656.2Mb (AR), 439.4Mb (MLP), 381.2Mb (HC), 344.3 (KN), 206.7 (SOK) and 171.0Mb (SZTUM) of the genome were detected. Mean block lengths were estimated as 106.5±138kb, 75.9±120kb, 66.4±109kb, 63.4±109kb, 37.3±80kb and 35.3±81kb for AR, MLP, HC, KN, SOK and SZTUM, respectively. A visible similarity in the decay of LD across the genome, as well as in trends of historical N e, were found for breeds representing the same horse type. Differences in the span of haplotype block structures were found between AR and Polish native horse breeds, which may reflect different demographic population histories and differences in intensity of selection. [ABSTRACT FROM AUTHOR]

A total of 127 normal placentas from Arabian mares resident in the United Arab Emirates were examined. The mean linear dimensions of the placenta were, on average, 84% of those previously recorded for the placentas of the Thoroughbred. Significant differences in the size of the allantochorion between primigravid and multiparous mares were seen only in the linear dimensions of the body portion. The pregnant horn was more commonly on the right than left side of the uterus (P =.01; 74/127; 58%). Cord attachment was primarily at the base of the two placental horns (112/127; 88%), with the remainder showing anomalies from this position. The mean (±SEM) total length of the umbilical cords was 62.2 ± 1.2 cm, being composed of the allantoic portion (29.7 ± 0.9 cm) and amniotic portion (32.5 ± 0.6 cm), which averaged 53 ± 0.01% of the total length. The amniotic portion was usually, but not always, longer than the allantoic portion (79/127; 62%). Longer cords were associated with a greater proportion of allantoic length. An enlarged yolk sac remnant (YSR) was present in 16/127 (13%) placentas. Cords with YSRs displayed a significantly longer allantoic portion than those without (P =.02). The total cord length was not correlated with the weight or area of the allantochorion or amnion, any linear measurement of the allantochorion, gestation length, the month of foaling, parity of the dam, or birthweight or sex of the foal. The purpose for which the mare was bred (i.e., racing or showing) influenced the cord length, those of show mares being significantly longer. • Body width and length of the allantochorion increase with parity. • The pregnant horn more commonly occupies the right side of the uterus. • In 12% of placentas, the cord attachment site was not located at the bifurcation. • The mean (±SEM) total umbilical cord length was 62.2 ± 1.2 cm. • Longer cords were proportionately composed more of the allantoic portion. [ABSTRACT FROM AUTHOR]