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Topic:Horse Breeds
Horse breeds represent the diverse genetic and phenotypic variations found within the species Equus ferus caballus. These breeds are categorized based on characteristics such as size, conformation, coat color, and temperament, which have been selectively bred over centuries to fulfill specific roles and functions. Common classifications of horse breeds include light horses, draft horses, and ponies, each serving different purposes ranging from riding and racing to work and companionship. This page aggregates peer-reviewed research studies and scholarly articles that explore the genetics, history, and functional attributes of various horse breeds, as well as their impact on equine management and breeding practices.
Blood group and protein polymorphism gene frequencies for seven breeds of horses in the United States. Gene frequencies at 20 blood group and protein polymorphism loci (A, C, D, K, P, Q, U, Al, Tf, Pi, Xk, Es, Gc, PGD, CA, Cat, PGM, AP, Hb and PHI) are given for seven horse breeds in the United States (Thoroughbred, Arabian, Standardbred, Morgan, Quarter Horse, Paso Fino and Peruvian Paso). These data are used to calculate that the battery of tests is at least 96% effective for recognizing incorrect paternity in these breeds. In addition to paternity testing, these tests can be applied to studies of breed relationships.
Quantification of unscheduled DNA synthesis in mononuclear leukocytes of the horse. This study compares the relationship between N-acetoxy-2-acetylaminofluorene (NA-AAF) and u.v. induced unscheduled DNA synthesis (UDS) and their respective relationships to age and blood pressure in horse mononuclear leukocytes with earlier, similar investigations on human leukocytes. U.v. induced UDS was found to proceed more rapidly than NA-AAF induced UDS. A pronounced lag period associated with the rapid demand for 3H-dThd into DNA after u.v. damage was observed. NA-AAF induced UDS correlated significantly with NA-AAF binding, age and the blood pressure of male horses. UDS values, induced ...
Equine lymphocyte antigens in four major Belgian horse populations. Contribution to serology and antigen distribution. 158 Belgian Saddlebreds, 130 Belgian Trotters, 108 Belgian Draft horses and 92 Shetland ponies have been typed for serologically defined antigens at the ELA and ELY systems. Gene frequencies were estimated in each breed for the internationally established ELA, ELY-1 and ELY-2 alleles as well as for locally assigned additional ELA markers and for subtypes of ELA-W3, W9 and W11. The distribution of ELA alleles was in agreement with the expected Hardy-Weinberg equilibrium for the 4 horse breeds described here. Differences in gene frequencies between these main Belgian horse populations were obser...
Controlled tests of activity of ivermectin against natural infections of migratory large strongyles and other internal parasites of equids. Four controlled tests (experiments A, B, C, and D) were conducted in naturally infected yearling equids to evaluate activity of ivermectin (0.2 mg/kg IM) against migrating Strongylus vulgaris and S edentatus in mesenteric arteries and ventral abdominal wall, respectively. Data were also obtained on activity against other internal parasites of the gastrointestinal tract and eyeworms. The type and number of equids in the experiments were as follows: experiment A-3 ponies, 2 treated and 1 non-treated; experiment B-4 mixed-bred horses, 2 treated and 2 nontreated; experiment C-5 mixed-bred horses, ...
Genetic organization of the polymorphic equine alpha globin locus and sequence of the BII alpha 1 gene. The equine alpha globin gene complex comprises two functional alpha genes and an alpha-like pseudogene arranged in the order 5'-alpha 2-(5kb)-alpha 1-(3kb)-psi alpha-3'. A single (embryonic) zeta-like sequence lies within a 12 kb region 5' to the alpha 2 gene. We have determined the sequence of the alpha 1 gene of the BII haplotype, one of two most common haplotypes (the other being BI) which encode alpha globins with either Tyr (BI) or Phe (BII) at codon 24 in both linked alpha genes. In BI and BII the non-allelic alpha 2 and alpha 1 genes respectively code for Gln or Lys at codon 60, thus ac...
Techniques and applications of transabdominal ultrasonography in the pregnant mare. To establish the feasibility of utilizing high-frequency ultrasound to image equine fetal development transabdominally, in vitro and in vivo observations were made. Three fetuses retrieved from mares that died from various causes were scanned in vitro to establish fetal images from various orientations. A total of 50 mares ranging in age from 4 to 16 years and representing various breeds were scanned intermittently from 100 days of gestation to parturition. Fetal parts, amniotic fluid, placental membranes, and motion patterns could be reliably identified. Fetal heart rates decreased from 180 b...
Radiological investigations of osteochondrosis dissecans in Standardbred Trotters and Swedish Warmblood horses. A total of 106 Standardbred Trotters and 27 Swedish Warmblood horses, with a radiological diagnosis of osteochondrosis dissecans, were studied over a six year period. The majority were young horses. No statistical difference in frequency between the sexes was demonstrated. In both breeds osteochondrosis was most common in the hock joints, the site of predilection being the distal dorsal tip of the intermediate tibial ridge. On radiographs the lesions of the hock joints were graded on a scale from 0 to 5 according to size, number and localisation of defects and visible loose bodies. The sizes o...
Direct evidence for linkage of roan and extension loci in Belgian horses. A bay roan Brabant Belgian stallion (ERn/ ern) was bred to eight chestnut American Belgian mares (ern/ ern), producing 57 foals. Thirty foals were bay roan, 25 were chestnut, one was bay, and one was chestnut roan. The recombination rate was 0.035 +/- 0.024, indicating fairly close linkage between the roan (Rn) and extension (E) loci.
Kinetics of electron transfer between mitochondrial cytochrome c and iron hexacyanides. The reduction of horse and Candida krusei cytochromes c by ferrocyanide has been studied by 1H NMR spectroscopy and the reaction found to involve a precursor complex of ferrocyanide bound to ferricytochrome c (pH* 7.4, 2H2O, I = 0.12, and 25 degrees C). The electron transfer rate constants for the reduction of the two ferricytochromes by associated ferrocyanide were found to be the same at 780 +/- 80 sec-1 but the association constants for binding of ferrocyanide to ferricytochrome c were significantly different: horse, 90 +/- 20 M-1 and Candida, 285 +/- 30 M-1. The different association const...
Respiratory studies in foals from birth to seven days old. Respiratory measurements and blood-gas and acid-base values are reported in nine term induced foals. Measurements were performed at 2, 15, 30 and 60 mins, 4, 12, 24 and 48 h, and four and seven days after birth. Minute respiratory volume was significantly lower at birth than values from 12 h old. Tidal volume peaked at 60 mins old, while respiration rate decreased significantly at 15 mins after birth. Oxygen consumption was high at birth and decreased to its lowest values at 24 and 48 h. The respiratory exchange ratio and ventilatory equivalent showed few significant changes to seven days, as ...
Exercise-induced pulmonary hemorrhage in exercising Thoroughbreds: preliminary results with pre-exercise medication. Thoroughbreds with a confirmed history of exercise-induced pulmonary hemorrhage (EIPH) were treated pre-exercise with atropine sulfate, cromolyn, ipratropium or furosemide. Atropine prevented EIPH in 3 of 3 trials in 1 horse, while having no significant effect on bleeding status in the other 2 horses. Pre-exercise treatment with cromolyn had no significant effects in the 3 horses. Pre-exercise treatment of ipratropium was apparently responsible for preventing EIPH in 17 out of 18 trials in 2 horses. The pharmacologic properties of ipratropium in the horse have not been studied, but based on hu...
Intracranial haemorrhage in pre-viable, premature and full term foals. A neuropathological examination was carried out on the brains of 58 foals. Forty-two were pony foals induced at various periods of gestation from 200 days onwards. Two were pre-viable pony foals delivered by caesarean section and 14 were Thoroughbred foals (one set of twins, two stillborn, five premature, two dysmature, two convulsive and one induced). The only significant pathological change involved intracranial haemorrhage. Subarachnoid haemorrhage occurred in all of 10 pony foals induced before 301 days of gestation and in two pony foals born by caesarean section at 270 and 280 days gestat...
Mammary secretions in normal spontaneous and induced premature parturition in the mare. Total calcium, total protein, albumin and globulin content were determined in 49 samples of mammary secretions from 37 crossbred and Thoroughbred mares. The mares were divided into three categories: Group 1--post partum samples from spontaneous full term Thoroughbred deliveries (n = 20); Group 2--pre- and post partum samples from spontaneous full term Thoroughbred deliveries (n = 6); Group 3--pre- and post partum samples from induced premature deliveries in crossbred mares (n = 11). Calcium concentrations of the mammary secretions proved useful in predicting full term and also in assessment of...
Effects of centrifugation, glycerol level, cooling to 5 degrees C, freezing rate and thawing rate on the post-thaw motility of equine sperm. Five experiments evaluated the effects of processing, freezing and thawing techniques on post-thaw motility of equine sperm. Post-thaw motility was similar for sperm frozen using two cooling rates. Inclusion of 4% glycerol extender was superior to 2 or 6%. Thawing in 75 degrees C water for 7 sec was superior to thawing in 37 degrees C water for 30 sec. The best procedure for concentrating sperm, based on sperm motility, was diluting semen to 50 x 10(6) sperm/ml with a citrate-based centrifugation medium at 20 degrees C and centrifuging at 400 x g for 15 min. There was no difference in sperm mo...
Congenital nuclear cataracts in the Morgan horse. Nuclear cataracts were found in 2 groups of related Morgan horses. The cataracts were finely reticulated central spherical translucencies that sometimes extended to the region of the posterior "Y" suture. The cataracts were not associated with other ocular defects and did not impair vision. In 1 group of 8 horses, 5 were affected; in the other group, 6 of 8 were affected. Although a pattern of inheritance could not be determined, the familial distribution of the cataracts supported the conclusion that the defect was a heritable disorder.
Sequence of the high-activity equine erythrocyte carbonic anhydrase: N-terminal polymorphism (acetyl-Ser/acetyl-Thr) and homologies to similar mammalian isozymes. The amino acid sequence of the high-activity equine erythrocyte carbonic anhydrase (CA-II) has been determined. Two different N-termini are noted, the C1 form having an N-acetyl-serine and the C2 form an N-acetyl-threonine. The sequence of the equine enzyme is most homologous to the human CA-II isozyme, with 224 of the 259 residues being identical.
Diurnal changes in the metabolic indices in the blood of racing Arabian horses. In 8 stallions and 6 mares of pure Arabian breed the diurnal changes in the levels of lactic and pyruvic acid, glucose, and alkaline reserve were studied. All of them showed distinct diurnal changes but they failed to fulfil the criteria of circadian rhythm according to Halberg. It was found that all peaks occurred during the dark phase of the 24 h period except the glucose level in the stallions. Three of the indices studied showed higher mean diurnal levels in the mares than in the stallions. Only in the glucose level the mean values were reversed.
The relationship between alpha-MSH level and coat color in white Camarque horses. White horses are subject to age-dependent coat depigmentation. They are dark gray or black at birth and lose their coloring between their second and fourth year. Beginning at about age 10 their coat takes on a characteristic silver-gray coloring. The purpose of this paper was to find out to what extent the endogenic alpha-MSH level changes with the change in pigmentation. alpha-MSH plasma levels were determined by radioimmunologic analysis in 3 age groups of white Camarque horses: age group 1 consisted of dark horses with a mean age of 1.2 years and a mean alpha-MSH level of 106.4 pg/ml +/- 18...
Epidemiological survey of Corynebacterium equi infections on five Ontario horse farms. Corynebacterium equi was cultured from manure or soil on five horse-breeding farms in Ontario at monthly intervals on three occasions during the summer of 1982. The organism was widespread. Contamination by C. equi of the loafing paddock and pasture areas was significantly greater in a farm established 30 years than in two established for four and six years and there was a significant correlation between the C. equi burden in stables, paddocks and pastures and the length of use of the five farms for horses. In all farms, numbers of C. equi in pasture soil exceeded numbers in fresh manure, sugg...
Survey of resting blood pressure values in clinically normal horses. Resting coccygeal blood pressure values were measured, indirectly, on 296 horses (97 Thoroughbreds, 97 Standardbreds and 102 hacks). Blood pressure was found to vary with the class of horse examined; on average Thoroughbreds had significantly higher values than Standardbreds and hacks, whereas blood pressures of the last two groups were not significantly different. There was no demonstrable effect of sex, height or heart rate on blood pressure, but temperature and age did influence the value recorded. Mean (+/- sd) (n = 296) coccygeal uncorrected values (systolic pressure/diastolic pressure) w...
Genetic linkage in the horse. II. Distribution of male recombination estimates and the influence of age, breed and sex on recombination frequency. In the present study an extensive amount of data, comprising more than 30,000 offspring in total, was analyzed to evaluate the influence of age and sex on the recombination frequency in the K-PGD segment of the equine linkage group (LG) I and the influence of age, breed and sex on recombination in the Al-Es segment of LG II. A highly significant sex difference is reported for both segments. Male and female recombination values in the K-PGD segment were estimated at 25.8 +/- 0.8 and 33.3 +/- 2.5%, respectively. Similarly, recombination was less frequent in the male (36.6 +/- 0.7%) than in the f...
