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Topic:Genetics
Genetics in horses encompasses the study of hereditary traits and the genetic makeup that influences various characteristics and health conditions in equine populations. This field involves the analysis of genes and their functions, inheritance patterns, and the impact of genetic variations on traits such as coat color, performance ability, and susceptibility to diseases. Research in equine genetics employs techniques such as genome mapping, sequencing, and genetic testing to identify specific genes and mutations associated with these traits. This page gathers peer-reviewed research studies and scholarly articles that explore the genetic basis of equine traits, the methodologies used in genetic research, and the implications for breeding, health management, and conservation of horse breeds.
Congenital intestinal aganglionosis in white foals. A congenital and probably hereditary neurological defect has been identified in the intestinal tract of six foals produced from the breeding of overo (a type of spotting pattern) horses. The foals had white hair and pink skin with the exception of occasional pigmented foci about the muzzle, ventral abdomen, and hindquarters. The foals appeared normal at birth, but within a few hours developed symptoms of colic. At necropsy, the only significant finding was a narrow, pale segment of large intestine. This abnormality either was confined to the small colon and rectum or involved the entire colon ...
Joint report of the First International Workshop on Lymphocyte Alloantigens of the Horse held 24-29 October 1981. Six equine lymphocyte alloantigen (ELA) specificities were defined by an international antiserum comparison test and workshop held in 1981. Twelve laboratories from four countries submitted 195 antisera for analysis. The antisera were exchanged among the 12 laboratories and tested in a standard lymphocyte microcytoxicity assay against the isolated lymphocytes at 1009 horses of several breeds. The data was pooled and analysed by a single computer analysis. The calculated chi 2 values of all cells with all antisera provided comparisons between antisera. Fifteen antisera clusters were formed by t...
Transmission studies with the contagious equine metritis bacterium in albino Swiss mice. Aspects of experimental transmission of the causal bacterium of contagious equine metritis (CEM) to albino Swiss mice were investigated. Whereas infection was established in the majority of female mice, the organism was recovered from only a limited number of male mice after challenge. No clinical evidence of infection was observed in the experimental mice. There was only one instance of presumptive venereal transmission of the CEM bacterium. One third of infected females conceived and had normal litters.
Streptokinase-dependent delayed activation of horse plasminogen. Complete activation of purified horse plasminogen to plasmin was obtained with a 1:10 molar ratio of streptokinase to plasminogen after 5 min of incubation at 37 degrees C. At a 1:1 molar ratio, maximal activity did not appear until 15-30 min, while at a ratio of 6:1 complete activation was delayed for 120-180 min. Gel filtration studies of isotopically labeled streptokinase and horse plasminogen suggest that the delay was due to impaired formation of a streptokinase-plasminogen complex. The predominant streptokinase moiety within the streptokinase-plasmin complex which forms from the streptok...
Hereditary lethal arthrogryposis (“muscle contracture”) in horses. In 4 female foals of the Norwegian horse breed, "Fjord Horse", congenital arthrogryposis of the limbs are described. The disorder was mainly limited to the hind limbs and associated with polydactylia and partly with brachygnathia superior and cleft palate. The defective foals were paternal halfsisters of 4 normal foals (1 female + 3 males), sired by the stallion "Bingo" 1804, which was phenotypically quite normal. The disorder being lethal, is possibly caused by a sex-limited or a strongly sex-influenced dominant gene.
Structure and function of the major histocompatibility complex in domestic animals. The major histocompatibility complex (MHC) is a genetic region that has been intensively studied for the past 2 decades. Interest in the MHC has been high because of (i) the particular involvement of the MHC in transplantation reactions, including organ allograft rejection in human beings; and (ii) the more general role of MHC gene products in the genetic control of immune responses in all mammals. The MHC has several remarkable properties that include a distinctive genetic structure which has been well-preserved through evolution, and the extreme plasticity of form of the principal MHC genes,...
Blood groups in animals. The membrane of RBC is literally peppered with a great variety of antigenic determinants (blood factors). Some are fixed genetically, ie, they occur on the RBC of all members of the species under study. Others segregate genetically, ie, they occur on the RBC of some but not all members of the species under study. It is these segregrating determinants that form the blood groups proper, the classic example being blood factors A and B of the ABO system of human blood groups. The number of blood group determinants varies considerably between species (eg, greater than 80 in domestic cattle to only ...
Duration of maternally derived immunity to tetanus and response in newborn foals given tetanus antitoxin. Serum tetanus antitoxin (TAT) concentrations were measured in a group of 30 foals from birth to 4 months of age. Five of 30 foals (16.6%) had serum titers less than 0.01 IU of TAT/ml by 1 month of age. At 2 months of age, 17 of 28 foals (60.7%) had titers less than 0.01 IU/ml. By 3 months of age, 22 of 29 (75.5%) foals tested had titers of less than 0.01 IU/ml. At the age of 4 months, 24 of 29 foals (82.1%) had titers of less than 0.01 IU/ml. The TAT given to foals at birth resulted in an immediate increase in titer when circulating antitoxin was absent or minimal. Titers considered protective...
Microsporum equinum in North America. Microsporum equinum was isolated in Ontario, Canada, from five human and two equine cases of ringworm infection. This dermatophyte was previously recovered from North American horses on several occasions, but was considered to be M. canis. We regard M. equinum as distinct from M. canis. It can be differentiated from M. canis by the smaller size of its macroconidia, its failure to perforate hair in vitro, its poor growth and sporulation on bromocresol purple casein dextrose agar, and its incompatibility with Nannizzia otae, the telemorph of M. canis.
[Sarcocystis bertrami Doflein, 1901, a sarcosporidia of the horse. Equus caballus]. No abstract available
Equine leucocyte antigen system. III. Non-MHC linked alloantigenic system in horses. A new, non-MHC linked alloantigenic membrane antigen on the equine lymphocytes is described. This antigen was characterized with alloantisera in the two-stage microcytotoxicity test and designated as ELy-1 antigen. The frequency of ELy-1 antigen positive animals in various populations is close to 50%. ELy-1 shows an autosomal, dominant inheritance. Since an allelic antigen (s) could not be demonstrated in family studies, it is assumed that only two alleles ELy-1+ and ELy-1- exist. The ELy-1 antigen in positive animals is expressed on both T and B lymphocytes but it is not present on erythrocyt...
Glutathione peroxidase and selenium in the blood of healthy horses and foals affected by muscular dystrophy. When blood selenium concentrations and glutathione peroxidase activity was measured in 30 standardbred horses a significant correlation was found (r = 0.97). A comparison between blood GSH-px activity in clinically healthy foals, foals affected by muscular dystrophy (MD) and their respective mares was also done. There was no difference in GSH-px activity between the healthy foals and the MD foals or between the corresponding mares.
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...
Types of Pseudomonas aeruginosa isolated from horses. Pseudomonas aeruginosa isolates from equine clinical material were categorised according to their serotype and phage type. Epidemiological evidence showed that serotypes 02a, 03, 04, 06, 09 and 010 were the cause of genital and non-genital infections; somatic type 03 accounted for 50 per cent of isolates. The laboratory tests used were of no value in predicting whether or not a particular isolate was likely to be a venereal pathogen, but all the serotypes encountered had the potential to be pathogenic, given a favourable environment in which to multiply.
[Some physicochemical properties of native and polymerized glutaraldehyde-treated horse heart cytochrome c]. Glutaraldehyde treatment does not change the absorption of cytochrome c either in the visible or in UV spectra. It brings about the formation of dimers, trimers and high-polymeric forms of cytochrome c and shifts the pI of all cytochrome c isoelectric fractions to more acid pH. Polymerization also results in changes of kinetic parameters of cytochrome c benzidine reaction increasing its affinity to 3,3-diaminobenzidine with a simultaneous decrease in the effectiveness of H2O2 binding. These biochemical changes can be related to immunochemical differences of native and glutaraldehyde-treated cy...
Deficiency of interferon-gamma but not interferon-beta in Arabian foals with severe combined immunodeficiency. The results of a study on the induction of IFN-alpha, IFN-beta, and IFN-gamma in normal and SCID foals showed a deficiency of IFN-gamma but not IFN-beta in SCID foals. The ability of SCID mononuclear cells to produce IFN-alpha in response to poly I:C but not to NDV may indicate a partial deficiency of IFN-alpha in SCID foals. The deficiency of IFN-gamma and presence of IFN-beta in SCID foals supports the classification of IFN-gamma and IFN-beta as immune and nonimmune interferons, respectively. Furthermore, the deficiency of IFN-gamma in SCID foals may in part explain the high susceptibility t...
Lymphocyte alloantigens of the horse. I. Serologic and genetic studies. A genetic system controlling lymphocyte alloantigens of the horse is described. Alloantisera to paternal histocompatibility antigens induced as a result of pregnancy in mares were used in an antibody-mediated complement-dependent microcytotoxicity assay to define 15 Equine Leukocyte Antigen (ELA) specificities using cluster analysis. In this study 369 sera were screened for alloantibody using lymphocytes from 10 randomly selected, unrelated horses. A high proportion (83%) of these sera were found to be positive for antibody to lymphocyte alloantigens. After initial cluster analysis, 120 of the...
Twinning in mares: A survey of veterinarians and analyses of theriogenology records. Responses of 22 veterinarians to a questionnaire and the records of three brood-mare farms were examined to obtain information on twinning. The incidence rates of multiple ovulations on the three farms were 9%, 11%, and 22%. The multiple ovulation rate was reduced 42-67% in foaling mares compared to barren and maiden mares. Multiple ovulations were significantly more frequent in Thoroughbreds (19%) than in Quarter Horses (9%) and Appaloosas (8%). Both the questionnaire and the farm records indicated a high degree of repeatability of multiple ovulations and twin pregnancies within mares and wit...
