Topic:Breed Differences
Breed differences in horses encompass variations in physical characteristics, behavior, and physiological traits among different horse breeds. These differences arise from selective breeding practices aimed at enhancing specific attributes such as speed, endurance, strength, or temperament. Physical attributes can include variations in size, coat color, and conformation, while behavioral traits may involve differences in temperament and trainability. Physiological differences can affect metabolism, disease susceptibility, and performance capabilities. This topic includes peer-reviewed research studies and scholarly articles that explore the genetic, environmental, and historical factors contributing to breed differences, as well as their implications for equine management, health, and performance.
Prevalence and intensity of non-strongyle intestinal parasites of horses in northern Queensland. A quantitative post-mortem study of 57 horses from northern Queensland was done to determine the prevalence and intensity of non-strongyle intestinal parasites. The following species (% prevalence) were found: Draschia megastoma (39%); Habronema muscae (43%); Gasterophilus intestinalis (34%), G. nasalis (30%); Parascaris equorum (15%); Strongyloides westeri (6%); Probstmayria vivipara (2%); Oxyuris equi (26%); Anoplocephala magna (2%); A. perfoliata (32%). Mean parasite numbers of individual species ranged from 10 to 1310. Prevalence and intensity data were compared to recent studies in Wester...
Y chromosome length variation and its significance in the horse. The results of Y chromosome measurements in 31 horses are presented. The Y chromosome was identified using G-, R-, and C-banding techniques. From G-banded metaphase spreads, total X and Y chromosome and separate proximal (P) and distal (D) Y-band measurements were made. Within this group, the Y/X ratio (%) for each animal varied from 18.93 to 43.95, with an overall mean of 34.85 and a coefficient of variation (CV) of 16.12. The overall mean P/X ratio (%) was 23.57 with a CV of 20.57, compared with an overall mean D/X ratio (%) of 11.26 with a CV of 15.18. The group studied included 27 Thorough...
Serum profiles of vitamins A, E and D in mares and foals during different seasons. Twenty mares and 15 foals of the Finnhorse breed were used to determine serum levels of vitamins A, E and D during different seasons. Monthly serum samples were analyzed from mares for 22 mo and from foals for 13 mo after birth. The horses were kept on pasture from early June until early October and in stables during the winter months. Seasonal differences (P less than .001) were found in serum retinol, retinol to protein ratio, alpha-tocopherol and alpha-tocopherol to cholesterol ratio. Values were lowest from February through May and highest from June through August. Serum levels of retinol ...
Body condition scoring and weight estimation of horses. Three hundred and seventy two horses of varying breeds, height and fatness were weighed and measured for height at the withers. They were assessed for condition score by adaptation of a previously published method. The heart girth and length of 281 of the horses were also measured. Weight of horses was highly correlated (P less than 0.001) with height (r2 = 0.62), condition score (r2 = 0.22) and girth2 x length (r2 = 0.90). Nomograms were constructed to predict weight from height and condition score, and girth and length measurements. Weight can also be accurately estimated from the formula: (...
Evaluation of breed as a risk factor for sarcoid and uveitis in horses. The relationship between breed and the risk of developing sarcoid tumours or uveitis of unknown etiology was evaluated in a retrospective study of 16242 equine cases admitted between 1975 and 1987 to the New York State College of Veterinary Medicine Large Animal Hospital, and 3198 equine tissue samples sent to the New York State Veterinary Diagnostic Laboratory between 1977 and 1987. Of 120 sarcoid cases from the Large Animal Hospital, sarcoids were twice as likely to develop in Quarter Horses (odds ratio, OR = 1.8, P less than 0.05) relative to Thoroughbreds and less than half as likely to de...
Joint Report of the Fifth International Workshop on Lymphocyte Alloantigens of the Horse, Baton Rouge, Louisiana, 31 October-1 November 1987. Six laboratories participated in the Fifth International Workshop on Lymphocyte Alloantigens of the Horse, testing 132 alloantisera against lymphocytes of 880 horses chosen to represent different families and breeds. Most of the alloantisera were produced by lymphocyte immunization between horses matched at the ELA-A locus. All horses were also tested with antisera contributed to the workshop by participating laboratories which identified ELA specificities A1-A10 and W12-W21. Previously identified workshop specificities ELA-W14, W15 and W19 were accepted as products of the ELA-A locus based on...
[Iron and iron-binding capacity in the serum of clinically healthy horses]. Serum iron concentration and iron-binding capacity were determined in 34 respectively 35 clinically healthy horses of different sex, with the age of 3 to 21 years. In the Warm blooded horse, the Half bred, the Haflinger horse, the Heavy horse and the Arabian Haflinger the mean serum iron concentration amounted to 253 +/- 66 micrograms/dl, 202 +/- 87 micrograms/dl, 166 +/- 67 micrograms/dl, 183 micrograms/dl and 366 micrograms/dl, while the iron-binding capacity in the Warm blooded horse, the Half bred, the Haflinger horse, the Thoroughbred, the Heavy horse and the Arabian Haflinger ran up to 4...
Plasma antithrombin-III values in healthy horses: effect of sex and/or breed. Plasma antithrombin-III (AT-III) values were determined in 74 healthy horses by an automated spectrophotometric assay. The mean plasma AT-III value was 218% +/- 18% of normal human plasma. Plasma AT-III values did not differ significantly (P less than 0.05) among Thoroughbred, Standardbred, Quarter Horse, and other breeds or among mares, geldings, or stallions.
Enteroliths in horses. Many cases of enteroliths were reported in the nineteenth century but the number greatly decreased in the early twentieth century. However, in recent years the number of cases in certain parts of the United States such as California has greatly increased. The reasons for the increase are obscure. The intake of nitrogen, magnesium and phosphorus (the primary components of enteroliths) from water and food is likely to be a factor. Arabians may be more likely to develop enteroliths than horses of other breeds. A nidus such as a small stone is needed because a nidus has been found in every enterol...
[Endometrial cysts in the mare. 2. Clinical studies: occurrence and significance]. Endometrial cysts were found in 11 (13.4%) of 82 mares of various breeds by clinical examinations. Endometrial cysts were diagnosed by hysteroscopy and ultrasonic echography. Typical images are described. The importance of endometrial cysts is discussed with regard to differential diagnosis of early pregnancy and uterine pathology. There was no evidence of cysts in mares under 10 years of age. Mares with endometrial cysts had a 10% higher history of disturbed fertility than mares without endometrial cysts. Seven of nine mares with cystic structures in the uterus became pregnant. Endometrial cy...
Epidemiological features of 5009 cases of equine cryptorchism. Data from 16 North American veterinary university teaching facilities, 5009 cryptorchid horses, were analysed using relative risk methodology. In five breeds (Thoroughbred, Standardbred, Morgan, Tennessee Walking horse and Arabian), cryptorchism was diagnosed significantly (P less than 0.05) less frequently than expected by their representation in the hospital population. Three breeds, (Percheron, American Saddle horse and American Quarterhorse), plus ponies (as a group) and crossbred horses were significantly over-represented within the series. The over-representation of Quarter-horses was ev...
Relationships among serum immunoglobulin concentration in foals, colostral specific gravity, and colostral immunoglobulin concentration. Postpartum, presuckle, colostrum samples were collected from 100 mares. Colostral specific gravities significantly correlated (r = 0.9) with colostral immunoglobulin (Ig)G concentrations. Foal serum IgG concentrations highly correlated (r = 0.82) with specific gravities of the colostrum each foal ingested. Eight of 48 foals (17%) had serum IgG concentrations less than 400 mg/dl. The dams of these 8 foals had colostral sp gr less than 1.06 and colostral IgG concentrations less than 3,000 mg/dl. Foals had serum IgG concentrations greater than 520 mg/dl 24 hours after parturition, when the colost...
Prevalence of carpal fractures in thoroughbred and standardbred racehorses. The prevalence of carpal fractures was determined for 211 thoroughbred and 75 standardbred racehorses. Statistically significant differences were found in the location of fractures between the 2 breeds. In the thoroughbred and standardbred groups, total fractures (460) were distributed nearly equally between the left (224) and right (236) carpi. The most common site of fracture in the thoroughbred group was the distal aspect of the radiocarpal bone (112), whereas the most common site of fracture in standardbred horses was the proximal surface of the third carpal bone (61). Slab fractures were ...
Familial congenital occipitoatlantoaxial malformation (OAAM) in the Arabian horse. Familial occipitalization of the atlas with atlantalization of the axis was defined as a single congenital disease in Arabian horses following a clinical, radiologic, and morphologic study of 16 horses with congenital malformations of the occiput, atlas, and axis, and from a study of three reported cases. The constant morphologic features were interpreted as congenital atlantooccipital fusion, hypoplasia of the atlas and dens, malformation of the axis, and modification of the atlantoaxial joint. Atlantoaxial subluxation was also a frequent finding. The clinical syndromes shown by these horses ...
Electrophoretic markers of Andalusian horses: comparison of Spanish and Lusitanian lineages. Genetic variants at eight blood loci were analysed, disclosing in Andalusian breed six rare markers: variants J of transferrin, H of esterase, D and S of Xk, M and W of prealbumin. Two of these, TfJ and PrM appear as characteristic markers of Andalusian breed. Allelic frequencies showed minor differences between Spanish (300 horses) and Lusitanian (100 horses) populations. Comparison was established with historically related breeds, Thoroughbreds or Connemara, and with Arab horses because of a presumed relationship. No visible similarities in genetic profiles were found with two former breeds,...
Influence of age and breed of equid on plasma copper and zinc concentrations. Plasma ceruloplasmin activities and plasma Cu and Zn concentrations were determined in 215 clinically normal equids of various ages and breeds. Newborn foals, regardless of breed, were hypocupremic, compared with adolescent and mature horses. The mean plasma Cu concentration of newborn Standardbred-Thoroughbred (STD-TB) foals was 2.9 mumol/L, which was about one-sixth of plasma Cu concentrations of mature horses. Newborn draft-cross foals had higher (4.6 mumol/L) plasma Cu concentrations than did newborn STD-TB foals, but plasma Cu content was only one-fifth of the dams' concentrations. Draft-...
Breed and species comparison of amino acid transport variation in equine erythrocytes. The amino acid permeability of red blood cells from Equus caballus (thoroughbred, Arab, shire and pony), E przewalskii (Przewalski's horse), E asinus (donkey and mule) and E burchelli (common or plains zebra) was measured. Individual animals exhibited stable but widely differing rates of L-[U-14C]alanine uptake in the range 5 to 1554 mumol (litre cells)-1 h-1 (0.2 mM extracellular L-alanine, 37 degrees C). Of the thoroughbreds tested, 30 per cent had red blood cells which were essentially impermeable to L-alanine (5 to 10 mumol (litre cells)-1 h-1, giving transport rates similar to those found...
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...
Usefulness of lymphocyte typing to exclude incorrectly assigned paternity in horses. Lymphocyte typing can be used to detect incorrectly identified parentage of horses. Efficacies of lymphocyte typing to solve paternity questions were calculated using gene frequency estimates of equine lymphocyte antigen (ELA) markers for Thoroughbreds and Standardbreds. Probabilities that ELA typing will detect an incorrectly assigned sire were 68.7% in Thoroughbreds, 67.9% in pacing Standardbreds, and 62.0% in trotting Standardbreds. These calculations demonstrate that ELA typing is among the most efficacious genetic systems for solving paternity questions in horses. Likewise, it could also ...
Quantitative analysis of long-bone growth in the horse. Long-bone growth at the distal ends of the radial bones, the distal ends of the 3rd metacarpal bones, the distal ends of the 3rd metatarsal bones, and the proximal ends of the proximal phalangeal bones (of thoracic and pelvic limbs) was quantitatively analyzed in 9 Thoroughbred-Quarter Horse foals from birth to 2 years of age. Metal growth markers were surgically implanted in the bones of the animals at 2 to 4 days of age. Radiographs of the bones were made on the day of surgical manipulation, the next day, and then once a week for 8 months, and once a month thereafter for an additional 18 mon...
Ivermectin and an ivermectin-penicillin combination: a comparison of anthelmintic efficacy in horses. Ivermectin given IM at 200 micrograms/kg, alone or in combination with procaine penicillin G at 600 IU/kg, to 20 randomly selected young horses of various breeds reduced fecal strongyle egg counts from 400-4100 epg (avg greater than 1000) pretreatment to zero 7 days posttreatment. There were no systemic or injection-site reactions, either immediate or delayed, in any of the horses.
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...
Times of appearance and disappearance of colostral IgG in the mare. Pre- and postpartum colostral samples collected from 14 Arabian and 22 Thoroughbred mares were examined for color, consistency, and immunoglobulin (Ig)G concentration. Initial samples, obtained 3 to 28 days before mares had foaled, contained greater than 1,000 mg of IgG/dl. Mean concentration of IgG in colostrum of the Arabian mares at the time of parturition (T0) was 9,691 mg/dl and was significantly (P less than 0.05) higher than the average, 4,608 mg/dl, for the Thoroughbreds. Average times lapsed from T0 until the colostral IgG decreased to 1,000 mg/dl (T1,000) was 19.1 hours for the Arabi...
Pheochromocytoma in the horse and measurement of norepinephrine levels in horses. Ten cases of pheochromocytoma in horses were obtained from the literature and a computer search of medical records. The clinical, laboratory and pathological features of pheochromocytoma in horses were reviewed. Pheochromocytoma is a catecholamine secreting tumor which tends to occur in older horses without breed or sex predisposition. It is usually unilateral adrenal medullary in location and benign. Malignancy was present in one horse. The most common clinical signs were sweating, tachycardia, tachypnea, muscle tremor and anxiety; however the tumor may be asymptomatic. Clinical signs were no...
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...
Two-dimensional electrophoresis of horse serum proteins: genetic polymorphism of ceruloplasmin and two other serum proteins. Two-dimensional agarose gel (pH 8.6)-horizontal polyacrylamide gel (pH 9.0) electrophoresis of horse serum proteins revealed genetic polymorphism of ceruloplasmin (Cp) and two unidentified serum proteins tentatively designated serum protein 1 (SP1) and serum protein 2 (SP2). Family data were consistent with the hypothesis that the observed Cp and SP1 phenotypes were each controlled by two codominant, autosomal alleles. The three common SP2 phenotypes were shown to be controlled by two codominant, autosomal alleles. Population data and limited family data indicated the occurrence of two additio...
Mortality rates and associated factors in equine colic operations – a retrospective study of 341 operations. A retrospective survey of 300 surgical treatments for colic involving 341 interventions was carried out to determine mortality rates and associated factors. These horses had been referred to the Ontario Veterinary College over the period September 1974 to February 1980. Data from the case records was collected and stored on a computer and statistical analysis was carried out using X(2) tests.Fifty percent (150/300) of the horses survived to be discharged from the hospital. Fifty-two horses were euthanized during the operation and another ten horses should have been; if these cases are excluded...
Population studies on the ELA system in American standardbred and thoroughbred mares. 336 Standardbred mares and 334 Thoroughbred mares in the vicinity of Lexington, Kentucky, were lymphocyte typed for 11 allelic antigenic specificities of the equine lymphocyte antigen (ELA) system. The Standardbred mares were divided into a population of pacers and a population of trotters. Substantial differences in ELA gene frequencies were found between the 3 groups. When the distribution of antigens within populations were compared to Hardy-Weinberg equilibrium expectations, relatively good agreement was found.
Reproducibility and the influence of age on interspecimen determinations of blood pressure in the horse. 1. The reproducibility of blood pressure determinations on 103 male horses gave an average coefficient of variation of 5.0%. 2. Different parameters affecting the methodology of blood pressure measurements were separately analysed; i.e. size of specimen, size of cuff in relationship to tail circumference and temperature of the environment. 3. A strong positive linear correlation between age and blood pressure in the horse was established for two breeds with widely varying genetic background--Swedish Warmbloods and Arabians.
Equine lymphocyte antigens in a Welsh pony family. Lymphocytes from an extended family of Welsh ponies were tested in a microcytotoxicity test against Thoroughbred and Arabian horse-derived antisera, which defined 4 and 6 equine lymphocyte antigen (ELA) specificities, respectively. Mixed leukocyte culture (MLC) tests were also performed. Welsh pony lymphocytes reacted to the Thoroughbred antisera. Most of the ponies' lymphocytes showed reactivity to 2 of the Thoroughbred ELA specificities, the offspring inheriting 1 antigen from each parent. Antigenic determinants were only partially demonstrated with Arabian antisera, although results indicat...