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.
Moorthy AR, Spradbrow PB, Eisler ME.Vaginal swabs from 19 mares and penile swabs from 4 stallions were cultured for mycoplasmas. A single semen sample from one of the stallions was also examined. Twelve vaginal swabs and 2 penile swabs yielded mycoplasmas. Ten of the positive vaginal swabs were from mares with vaginitis, or with a history of failure of conception. Two were from apparently healthy mares, but one had been served by an infected stallion. One positive penile swab was from a stallion with ulcerative lesions and the other from a stallion with breeding difficulties. All 14 strains of mycoplasma utilised arginine, and t...
Castles JJ, Gershwin ME, Saito W, Ardans A, Osburn B.Previous studies of human congenital immunodeficiency states and in vitro observations of lymphocyte response to mitogens have implicated two purine salvage pathway enzymes, andenosine deaminase (ADA) and nucleoside phosphorylase (NP), as critical in the normal maturation and/or function of the immune system. Based on this information, ADA and NP activities were examined in a variety of congenital and acquired animal models of dysimmunity. The animals studied herein included: congenitally athymic (nude) mice; congenitally asplenic mice; congenitally athymic-asplenic mice; motheaten mice; New Z...
Evenberg A, Meyer H, Verheij HM, de Haas GH.Two phospholipases A2 (EC 3.1.1.4) with different isoelectric points have been isolated from horse pancreas in high yield (880 mg/kg tissue). From pancreatic juice the more acidic species was isolated as the sole phospholipase A2. Upon tryptic activation the zymogens release a hepta- and pentapeptide, respectively from the N-terminal part of the protein giving rise to the formation of one single enzyme with a specific activity higher than that of pancreatic phospholipases A2 from other mammalian species. Horse phospholipase A2 differs from the porcine and bovine enzymes with respect to amino a...
Mitchell KF, Karush F, Morgan DO.The heterogeneity of the IgM response has been studied with anti-lactose antibody purified from the sera of seven horses. The IgM antibody was induced with a bacterial vaccine and the sera were obtained during a one-year period of immunization. L and H chain preparations were derived from separate bleedings of each horse and examined by analytical isoelectric focusing. All of the L chain preparations were complex and similar and, under optimum conditions, exhibited about 45 bands. Their similarity included almost identical concentration distributions over the entire pH gradient. Isoelectric ba...
Evenberg A, Meyer H, Gaastra W, Verheij HM, De Haas GH.The complete amino acid sequence of phosphlipase A2 (EC 3.1.1.4) from horse pancreas was determined. The protein controls of a single polypeptide chain of 125 amino acids and has a molecular weight of 13,927. The chain is crosslinked by seven disulfide bridges. The sequence was determined by automated Edman degradation of the intact protein and several of the large peptide fragments. Smaller peptides were analyzed by manual Edman degradation. Fragmentation of the peptide chain was accomplished by enzymatic digestion with trypsin, chymotrypsin, and thermolysin. The final overlap was found by di...
Moore JN, Mcilwraith CW.Two cases of osteochondrosis are presented. Lesions involving the lateral trochlear ridge of the femur are demonstrated on conventional radiographs and double-contrast arthrograms. A radiographic suggestion of osteochondrosis lesions in the patella is noted. Post mortem examination of one case confirmed the presence of partially free cartilaginous flaps. Reference is made to familial tendency to osteochondrosis in man, dog, pig and horse. The significance of rapid growth rate in the pathogenesis of the condition is also discussed.
Kang CH, Ferguson-Miller S, Margoliash E.1. The steady state kinetics for the oxidation of ferrocytochrome c by yeast cytochrome c peroxidase are biphasic under most conditions. The same biphasic kinetics were observed for yeast iso-1, yeast iso-2, horse, tuna, and cicada cytochromes c. On changing ionic strength, buffer anions, and pH, the apparent Km values for the initial phase (Km1) varied relatively little while the corresponding apparent maximal velocities varied over a much larger range. 2. The highest apparent Vmax1 for horse cytochrome c is attained at relatively low pH (congruent to 6.0) and low ionic strength (congruent to...
Walasek OF, Margoliash E.Donkey cytochrome c was shown to differ from horse cytochrome c by having a serine in position 47 rather than a threonine. The rest of the amino acid sequences are identical. Mules and hinnies, both males and females, carry equal amounts of horse and donkey cytochromes c. The same ratio is found in hinnies in preparations from heart tissue and from skeletal muscle. These results demonstrate that cytochrome c is transmitted in horse-donkey crosses as a simple Mendelian character which is neither sex-linked nor shows dominance. The cytochrome c gene is therefore located in the nuclear genome, as...
Kingsbury ET, Gaunt SN.The possible existence of multiple forms in the whey proteins of mare's milk was investigated. When individual milk samples from over 300 animals of various breeds were examined, four forms of an undescribed whey protein could be observed. Based on chemical properties and electrophoretic behavior, this protein has been identified tentatively as Whey1 (Wh1). A single case of heterogeneity in mare's alpha-lactalbumin also was observed. Previously described variation in beta-lactoglobulin could not be confirmed. The results of this study provide further evidence of the widespread, perhaps univers...
Lancaster WD, Olson C, Meinke W.Four of five spontaneous benign equine connective tissue tumors of unknown etiology and a bovine papilloma virus (BPV)-induced equine tumor contained BPV-specific DNA sequences as determined by DNA-DNA hybridization of DNA from tumors with BPV DNA labeled in vitro. Analysis of the kinetics of reassociation indicated that 20-75% of the BPV genome was present in the various tumors. The number of partial BPV genome equivalents ranged from 60 to 500 copies per diploid quantity of cellular DNA. Thermal denaturation profiles of duplexes formed between labeled BPV DNA and DNA from tumor cells indicat...
Ardans AA, Trommershausen-Smith A, Osburn BI, Mayhew IG, Trees C, Park MI, Sawyer M, Stabenfeldt GH.Immunotherapy was attempted in 2 Arabian foals with combined immunodeficiency. One foal was given a transplant of bone marrow from a selected full sibling, and 1 foal was given a fetal thymus transplant. Both foals died. Genetic evidence was obtained for survival of the transplanted tissues in both cases; however, a graft versus host reaction developed in the foal given the fetal thymus transplant.
Beech J, Dubielzig R, Bester R.Periodic episodes of diffuse central nervous system disease occurred in a yearling Thoroughbred gelding that had a history of frequent respiratory tract disease and stunted growth. Hepatic encephalopathy was diagnosed on the basis of history, clinical signs, prolonged bromsulphalein clearance, and increased blood ammonia content. Because of the poor prognosis and recurrent clinical signs the horse was euthanatized. Necropsy revealed an arteriovenous anomaly and thrombosis of the portal vein. Histologically, there was diffuse primary astrocytosis of the brain.
Mayhew IG, deLahunta A, Whitlock RH, Geary JC.Five horses of mixed breeding and 1 zebra with symmetric tetraparesis and ataxia were studied. There were 2 females and 4 males. Signs of illness were first noticed from birth to 12 months of age. Clinical and pathologic studies were performed when the animals were 4 to 24 months old. Two of the horses were related. All of the subjects had diffuse degenerative myeloencephalopathy. The degeneration was most pronounced in thoracic segments of the spinal cord. Ventral and dorsolateral funiculi were most severely affected. Axonal swelling and abnormal neuronal cell bodies were seen in the gray mat...
Allen GP, O'Callaghan DJ, Randall CC.Infection of cells with equine herpesvirus type 1 (EHV-1) or type 3 (EHV-3) resulted in the induction of a DNA polymerase activity distinguishable from host cell DNA polymerases by its high salt requirement for maximal activity. By column chromatography on DEAE-cellulose, DNA-cellulose, phosphocellulose, and hydroxyapatite, the EHV-1-induced polymerase was purified 500-fold with 1–2% recovery of total activity from the nuclei of infected hamster livers. The final enzyme preparation was homogeneous as judged by electrophoresis in sodium dodecyl sulfate-polyacrylamide gels. Calculations based ...
Dawson FL.Mares rarely ovulate in winter; ovulation is induced by increase in daylight length. Ova accumulate in the oviducts of unserved mares. During pregnancy, corpora lutea accumulate; all regress together at mid pregnancy. Plasma progesterone levels rise and oestrogen levels fall towards the end of pregnancy. Methods are available for early termination of pregnancy and for induction of parturition. Pregnancy can be diagnosed efficiently by rectal examination, and by immunological assay of pregnant mare serum gonadotrophin. Service at the foal heat is associated with an increased prevalence of early...
Cotchin E.Published figures from veterinary schools indicate that tumours may account for about 1 to 3 per cent of surgical cases. In this paper an account is given of clinical and pathological aspects of the tumours that are most likely to be encountered in practice, either as visibly or palpably detectable masses of tissue, or as internal tumours responsible for clinical signs. Amongst the common and important tumours dealt with, the most prominent are "equine sarcoid", squamous-cell carcinoma (of eye region and of glans penis), granulosa-cell tumours and melanomas. Well over a hundred references prov...
Borin G, Filippi B, Cavaggion F, Marchiori F.A solution synthesis is described of the partially protected N alpha-benzyloxycarbonylheptadecapeptide Z-Lys (Tfa)-Thr-Glu-Arg-Glu-Asp-Leu-Ile-Ala-Tyr-Leu-Lys (Tfa)-Lys (Tfa)-Ala-Thr-Asn-Glu (OBu t)-OBu t corresponding to sequence 88-104 of horse heart cytochrome c. The synthesis is achieved through the preparation of two subunits H1 (sequence 88-96) and H2 (sequence 97-104) and their linkage by an azide coupling step.
Hinton M, Jones DR, Lewis IM, Thomson PE.A multiple clotting defect in a 3 month old Arab colt foal associated with a deficiency in Factors VIII, IX, and XI is described. No abnormalities in clotting factors were detected in the colt's sire, dam, half-sister and half-brother.
Matthews AG.The author reviews some aspects of vision and ophthalmic disease in the horse and considers how some recent developments in ocular immunobiology and molecular pathology in other species may give pointers toward an understanding of disease processes in the horse.
Pazdera J, Hruban V, Pichrtová J, Müller Z, Jílek F.Using a multilocus DNA probe, individual - specific hybridization patterns, the so-called DNA fingerprints (TAB) were determined in six horse families by the DNA fingerprinting method. The probe with evolutionally preserved nucleotide sequence from bacteriophage M13 determines hypervariable regions placed in genomic minisatellite DNA. The use of this probe permits an identification of an individual and execution of paternity relationships with a probability over 99.99 per cent.
Merkt H.The use and techniques of artificial insemination for horses in Germany over the last 30 years is described. Artificial insemination appears to produce pregnancy percentages equal to those from normal breeding methods and its continued availability under veterinary supervision is recommended in conditions where disease, disability or distance debar normal service.
Möstl E.In the pregnant mare two different groups of oestrogens are produced by the placenta. The precursor of "classical" oestrogens (oestrone, oestradiol-17 beta and oestradiol-17 alpha) is dehydroepiandrosterone which originates from the fetal gonads. The ring B unsaturated oestrogens (equilin and equilenin and their derivatives) derive from farnesyl pyrophosphate by a pathway not involving cholesterol.