"Horses" is a broad topic that encompasses various aspects of equine biology, behavior, and management. This category includes studies on the anatomy, physiology, and genetics of horses, as well as their behavior, nutrition, and care. Research in this area may also cover the historical and cultural significance of horses, their roles in agriculture, sport, and therapy, and the challenges associated with their conservation and welfare. The page aggregates peer-reviewed research articles and scholarly studies that explore the multifaceted relationships between humans and horses, examining both scientific and socio-economic perspectives.
Patterson SD, Bell K.Three cases of abnormal expression of the equine protease inhibitory alleles, Pi F, L, and S1, were observed following the examination of 30,000 plasma samples by one-dimensional acid (pH 4.6) polyacrylamide gel electrophoresis. Characterization of the abnormal proteins in terms of isoelectric point, molecular mass, inhibitory spectra, and sialic acid content was performed using one- and two-dimensional electrophoretic techniques. The Pi F and S1 abnormalities were postulated to be the result of amino acid substitutions causing alterations in the processing of the carbohydrate side chains. No ...
Klei TR.This article briefly reviews new information on trichostrongylid stomach worms, spirurid stomach worms, tapeworms, threadworms, pinworms, intestinal protozoa, lungworms, eye worms, and numerous other aberrant parasites as it relates to prevalence, pathogenesis of diseases, and treatments.
Kowalczyk DF, Gunson DE, Shoop CR, Ramberg CF.To study the effects of environmental exposure to zinc and cadmium in immature foals, five pregnant ponies were raised within 2.9 km of the New Jersey Zinc Smelter in Palmerton, Pennsylvania. The mares and their foals were kept outdoors on timothy hay and orchard grass. The foals were examined daily for signs of illness and blood samples were taken monthly for estimation of serum zinc, copper, and ceruloplasmin levels. The foals were sacrificed at 2.5, 4.5, 8.5, 13.5, and 18.5 months of age. Necropsy revealed generalized osteochondrosis in joints of the limbs and cervical vertebrae, lymphoid h...
Turner TA.Navicular disease was diagnosed in 36 horses. Each horse was treated, using shoeing as the only major means of treatment. Phenylbutazone was used initially for 10 days after shoeing. Shoeing was designed to correct preexisting problems, enhance physiologic function of the foot, and ease breakover of the foot. The horses were evaluated over a period ranging from 12 to 54 months. The lameness improved in all horses. Thirty-one of the 36 horses treated were not lame when last evaluated. Shoeing was most effective when performed within 8 months of the first signs of lameness. Also, horses used for...
Clayton HM.P. equorum is a common and ubiquitous parasite that persists for many years in stables and on pasture in spite of good hygiene and anthelmintic control programs. Foals are usually infected early in life. During the migratory phase of the infection, clinical signs include coughing and a nasal discharge followed by depression and unthriftiness as the worms mature in the gut. Some foals die as a result of intestinal impaction or rupture. Patency is established around 3 months of age, and fecal egg counts may rise to very high levels. From 6 months of age onwards, the ascarid burden diminishes as ...
Lessard P, Wilson WD, Olander HJ, Rogers QR, Mendel VE.Twenty horses of various ages had inadvertently ingested alfalfa hay contaminated with Senecio vulgaris. Among them, 4 died of liver disease. Blood was collected from affected horses at monthly intervals for 7 months and at the 9th and 14th months. The following serum enzymes and chemical items were assayed: aspartate aminotransferase, lactate dehydrogenase, alkaline phosphatase, gamma-glutamyl transferase, sorbitol dehydrogenase, total bilirubin, BUN, glucose, cholesterol, inorganic phosphate, calcium, total protein, and albumin. Amino acid profiles, conjugated bile acids, sulfobromophthalein...
Klei TR.This article will focus on current information available on the equine immune response to helminth parasites as it relates to acquired resistance, hypersensitivity reactions, and vaccine development.
Krueger AS, Kinden DA, Garner HE, Sprouse RF.The morphologic and pathologic changes which occurred within the cecal mucosa of 4 horses during the onset of laminitis were determined from cecal biopsy materials obtained via a cecal fistula; the laminitis was induced with carbohydrate overload. The cecal epithelial mucosa specimens were obtained at 0 (base line), 24, 32, 48, and 72 hours after horses were given carbohydrate overload, and these were fixed and subsequently photographed. Changes in the cecal epithelium were examined by transmission electron and scanning electron microscopies. These histopathologic changes indicated that the mu...
Craig TM, Courtney CH.The kind of parasites a horse acquires depends upon its environment. Because patterns of transmission vary greatly with climate and management, no one worming program has universal applications. This article discusses epidemiology and control of equine parasites in the southern United States, where climates vary from warm temperate to subtropical and from humid in the southeast to arid in the southwest.
McDonnell SM, Garcia MC, Blanchard TL, Kenney RM.Ten pony mares that had developed stallion-like sexual behavior as the result of anabolic steroid treatment (boldenone undecylenate, 0.55 mg/kg intramuscularly (i.m.), once weekly for 12 injections) were evaluated for ability to aid in detecting estrus in cycling mares. In across-the-fence estrus detection trials, androgenized mares failed to elicit signs of estrus or diestrus. In 10-min pasture trials, in which each androgenized mare was placed in a group of 10 cycling mares (six of which were estrous), seven of the 10 androgenized mares elicited estrous behavior from one or two mares. Observ...
Andrews FM, Spurgeon TL.The histologic and histochemical staining characteristics of the triceps brachii (long head), extensor carpi radialis, gluteus medius, vastus lateralis, biceps femoris, semimembranosus, semitendinosus, and extensor digitorum longus muscles of 8 Thoroughbreds, 2 Quarter Horses, 1 Arabian, 1 Paso Fino, and 1 Shetland Pony are described. Muscle fiber morphology, staining distribution and intensity, amount of IM connective tissue, number of IM blood vessels and IM nerves, calcium-activated adenosine triphosphatase activity (CaATPase), percentage of fibertype population, percentage of relative fibe...
Roby KA, Reef VB, Shaw DP, Sweeney CR.A 15-year-old, Standardbred broodmare with an aortic sinus aneurysm developed rupture of the aneurysm with subsequent rupture of a tricuspid valve chorda tendinae, tricuspid regurgitation, acute right-sided congestive heart failure, and pulmonary thromboembolism. Shunting of blood from the aorta through the ruptured aneurysm into the right ventricle resulted in decreased renal perfusion and acute renal failure. Initially, treatment of the mare with analgesics, fluids, and digoxin resulted in clinical improvement, but the mare's condition deteriorated after 8 days and the mare was euthanatized ...
van Berlo MF, Rottier PJ, Horzinek MC, van der Zeijst BA.Equine arteritis virus (EAV) is a nonarthropod-borne togavirus. Six virus-specific RNA species have been found in EAV-infected cells having the following molecular weights: 4.3 X 10(6) (RNA1), 1.3 X 10(6) (RNA2), 0.9 X 10(6) (RNA3), 0.7 X 10(6) (RNA4), 0.3 X 10(6) (RNA5), and 0.2 X 10(6) (RNA6). RNA1 comigrates with the viral genome (M. F. Van Berlo, M. C. Horzinek, and B. A. M. Van der Zeijst, 1982, Virology 118, 345-352). All RNAs hybridized with a radio-labeled cDNA probe representing RNA6, indicating that they contain common sequences. To study this homology in more detail, RNase T1 oligon...
Kinney RM, Johnson BJ, Brown VL, Trent DW.A cDNA clone containing all of the 26 S mRNA coding region of the RNA genome of Venezuelan equine encephalitis (VEE) virus, virulent strain Trinidad donkey (TRD), has been constructed and sequenced. The nucleotide and deduced amino acid sequences of the 26 S RNA of VEE virus conform to the general organization of the alphavirus subgenomic mRNA. Excluding the poly(A) tail, the VEE 26 S RNA is 3913 nucleotides long with a protein coding region of 3762 nucleotides. Codon usage in the translated region is nonrandom and correlates well with that reported for Sindbis (SIN), Semliki Forest (SF), and ...
Palmer JE, Whitlock RH, Benson CE.Equine ehrlichial colitis (Potomac horse fever), a newly identified colitis of the horse, was first recognized in Maryland. In this report, we document occurrence of the disease in Pennsylvania, New Jersey, New York, Ohio, Idaho, and Connecticut. Enzootic areas were recognized by a characteristic pattern. Frequently there was a seasonal pattern and high prevalence of sporadic colitis in unstressed horses. The attack rate per farm generally was low. Horses on pasture, as well as those stabled, were affected. Clinical signs varied from fever and depression to severe diarrhea and laminitis. Occas...
Andrews FM, Rosol TJ, Kohn CW, Reed SM, DiBartola SP.Three horses less than or equal to 3 years old were evaluated because of stunted growth, weight loss, anorexia, depression, and lethargy of at least 1 month's duration. A neonatal foal was examined after its death. In each case, gross and microscopic renal lesions were compatible with bilateral renal hypoplasia (ie, cortical hypoplasia with severe medullary hypoplasia). In young horses with renal failure, bilateral renal hypoplasia should be considered in the differential diagnosis, and may represent a congenital lesion.
Koterba A, Torchia J, Silverthorne C, Ramphal R, Merritt AM, Manucy J.A base-line study of bacteria isolated from horses admitted to the Veterinary Medical Teaching Hospital during a 6-month period was performed to determine the extent of multiresistant nosocomial infections caused by gram-negative aerobic bacteria other than Salmonella spp. Results of this study indicated that 21.9% of the 105 horses from which cultures and sensitivities were available had developed nosocomial gram-negative aerobic infections, with high rates of resistance to gentamicin, kanamycin, and trimethoprim sulfadiazine, three of the most often prescribed antibiotics in this hospital. I...
Hacker DV, Moore PF, Buyukmihci NC.In 4 horses with ocular angiosarcomas, the common characteristics were that all horses were aged, and the neoplasms developed initially on conjunctival surfaces, grew slowly, and metastasized despite excision and radiation treatment. Histopathologically, the neoplasms were of 2 types: a capillary pattern of scant stroma and endothelial-lined vascular channels, and a solid pattern composed of sheets of pleomorphic cells with hyperchromatic nuclei and poorly defined cytoplasmic borders. Definitive diagnosis was made by use of factor VIII:RAg, which stained the tissues intensely.
Jones RS, Seymour CJ.The inhalational anaesthetic agent isoflurane was administered to 22 dogs and 21 horses undergoing a variety of surgical procedures. Satisfactory anaesthesia was produced in all the animals. The cardiopulmonary changes were similar to those observed with halothane. Rapid changes in the depth of anaesthesia were achieved and recovery from anaesthesia was rapid in both dogs and horses, which was a reflection of the relative insolubility of isoflurane. Recovery from anaesthesia in the horses was particularly smooth and rapid with the animals spending a greater part of their recumbency in the ster...
Masri MD, Merritt AM, Gronwall R, Burrows CF.Developmental changes of the gastrointestinal tract were probably responsible for the changes in faecal composition during the first week of the foals' life, which resembled small intestinal ingesta of adult horses, suggesting a minimal colonic modification. Faecal composition at the time of foal heat diarrhoea was suggestive of a secretory-type diarrhoea, in that the electrolyte concentration accounted for most of faecal osmolality and the faecal pH was alkaline. After foal heat diarrhoea faecal composition slowly approached that of adult horses. These data suggest that foal heat diarrhoea is...
Bowman KF, Dix LP, Riond JL, Riviere JE.Pharmacokinetics of ampicillin sodium (11 mg/kg), gentamicin sulfate (2.2 mg/kg), and combination ampicillin sodium-gentamicin sulfate were determined for serum and synovia of healthy horses given single-dose IV injection and were not found to be different from those from other reports; however, a prolonged terminal gamma-phase for gentamicin (8,498 +/- 1,842 minutes) in serum of horses was found to exist. Pharmacokinetic interaction between combination ampicillin sodium-gentamicin sulfate was not observed int he serum or synovia. Prediction of ampicillin sodium or gentamicin sulfate concentra...
Johnstone IB, Crane S.The incidence and nature of coagulation abnormalities in horses presented with colic and the possible prognostic value of these abnormalities was investigated. A coagulogram was performed on each of 24 adult Thoroughbred or Standardbred horses. A coagulogram consisted of measurements of eight parameters; platelet count, plasma fibrinogen, plasma antithrombin III (AT), partial thromboplastin time (PTT), prothrombin time (PT), thrombin clotting time (TCT), soluble fibrin monomer (SFM) and fibrin-fibrinogen degradation products (FDP). Retrospective determination of the cause of the colic and outc...
LeBlanc MM, McLaurin BI, Boswell R.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...
Johnson AL, Malinowski K.Studies were conducted in anestrous mares to characterize daily rhythms of cortisol in non-interrupted [ambient and 16 h light (L): 8 h dark (D)] and skeleton (10L:4D:2L:8D, 10L:6D:2L:6D and 10L:8D:2L:4D) photoperiods, and to determine if there exists a photosensitive phase for the secretion of prolactin. Neither peak or nadir concentrations of cortisol, nor the time of peak or nadir concentrations differed among photoperiod treatments. Highest concentrations (66 +/- 4.4 ng/ml, mean +/- SE) occurred between 0700 and 0900, whereas lowest concentrations (31 +/- 3.6 ng/ml) were found from 1900 to...
Ristic M, Holland CJ, Dawson JE, Sessions J, Palmer J.The recent establishment of a system for the continuous in vitro propagation of Ehrlichia risticii, the causative agent of equine monocytic ehrlichiosis (EME; synonym, Potomac horse fever), has facilitated the development of an indirect fluorescent antibody test for the diagnosis of this disease under laboratory and field conditions. The field diagnostic application of the test has aided in the recognition of the disease in 16 states of the United States and in 1 province of Canada. A limited epidemiologic study conducted between January and September 1985, in an area where the disease is know...
Clerbaux T, Serteyn D, Willems E, Brasseur L.The equine blood oxyhemoglobin dissociation curve has been traced in its entirety in standard conditions and the effects of temperature, pH and 2,3-diphosphoglycerate on this curve have been measured. When compared to that of human blood, the curve showed a higher oxygen affinity of hemoglobin (23.8 +/- 0.8 versus 26.6 mm Hg). The effect of the pH, expressed by d log P50/dpH, was found to be identical in man and horse (-0.47). The effect of temperature, however, expressed by d log P50/dT, proved to be lower in the horse (0.016 versus 0.024). The P50 showed an increase of 1 mm Hg each time 2,3-...
Aramaki S, Suzuki E, Ishidaka O, Momose A, Umemura K.The pharmacokinetics of caffeine (CAF) and its metabolites, dimethylxanthines, were examined in horses administered 2.5 mg/kg of CAF intravenously (i.v.), intramusculary (i.m.), or orally (p.o.). The plasma samples were extracted by Extrelut and the concentrations of CAF and metabolites were determined by high performance liquid chromatography (HPLC) with a short column. The pharmacokinetics of CAF after bolus i.v. injection were described by the assumption of a two-compartment model, and those of CAF after i.m. or p.o. administration were done by the assumption of a one-compartment model. The...
Calzone S, Wilkins C, Deckers I, Nankervis K.The EquiAmi Training Aid (ETA) is a popular training and rehabilitation tool, however knowledge about its effect on the equine gait is lacking. Understanding of its effects on equine kinematics, and the clinical relevance of these effects is vital to promote optimal use of training aids within training and rehabilitation programmes. Therefore, this study aimed to determine how the ETA influences horses' gait kinematics at walk and trot. Eight horses walked and trotted in-hand with and without the ETA. Optical motion capture was used to measure forelimb and hindlimb pro- and retraction angles, ...
True CK, Dotzel AR.Oral endoscopy is a valuable addition to the equine dental examination process. It enables veterinarians to visualize subtle oral disorders and is a useful client education tool. There are several commercially available oral endoscopic systems on the market. Practitioners can also assemble their own systems. An oral endoscope is used to perform a thorough and systematic oral examination and to visualize normal oral structures as well as oral disorders. It is also used to guide instrument placement during oral surgeries and other dental procedures.
Wiemer P, Bergman HJ, van der Veen H, Pruissen L.In the period from January 1995 until December 2000, 272 horses underwent a laparotomy for gastrointestinal disorders. The results of these surgeries were evaluated. From these 272 patients 176 (= 65%) were discharged in good health from the hospital. When the patients that were euthanized immediately after the start of the surgery, because of a fatal deterioration, were not taken into account, the short time survival rate was 77%. Strangulated small and large intestinal obstructions (48%) had a lower short time survival rate than non-strangulated obstructions (87%). Fatal postoperative compli...
Goulden BE, Anderson LJ, Davies AS, Barnes GR.A horse with rostral displacement of the palatopharyngeal arch was found to have a bilaterally symmetrical deformity of the laryngeal area. Both left and right cricopharyngeal muscles were absent. The shape of the thyroid cartilage was grossly abnormal and vestiges of the cricothyroid muscles were attached only to the cricoid cartilage. It was suggested that such an anomaly could have resulted from aberrant development of the fourth branchial arch.
Bohn A, Papageorges M, Grant BD.Ultrasonography and radiography were used to diagnose bicipital tenosynovitis and humeral osteitis in a horse with a history of lameness of 7 weeks' duration. Surgical exploration confirmed the diagnosis.
Zavodovskaya R, Eckert M, Murphy BG, Stover SM, Kol A, Diab S.Silicate associated osteoporosis (SAO) was diagnosed in an adult horse with the shortest documented exposure to cytotoxic silicates of 2 years. The horse was evaluated for a 6-months history of progressive back tenderness and acute onset of lameness. The horse had a marked (4/5) [American Association of Equine Practitioners scale] left forelimb lameness, moderate (2/5) hindlimb ataxia and weakness, and cervical pain upon palpation. Physical examination did not reveal clinical skeletal deformities or respiratory compromise. Radiographs revealed widespread, discrete, sharply delineated, osteoly...
Dzierzęcka M, Jaworski M, Purzyc H, Barszcz K.The aim of the study was to analyse selected densitometric and geometric parameters in the third metacarpal bone along the long axis in horses. The densitometric parameters included the cortical and trabecular bone mineral density, while the geometric parameters included the cortical, trabecular, and total areas, strength strain index X, strength strain index Y, and the polar strength strain index. Methods: The parameters were analysed using eight sections from 10% to 80% of the length of the bone. Peripheral quantitative computed tomography was used in the study. Statistical analysis was carr...
Pollitt CC, Holdsworth PA, Kelly WR, Meacham CS, Sheahan B.A single oral dose of ivermectin paste was administered to 12 horses with dermatitis and clinical signs typical of onchocerciasis. Two of the horses also had lesions of Queensland itch. Microfilarias of Onchocerca cervicalis were identified in fresh, macerated, skin biopsies from the neck, brisket or umbilical regions of all horses and microfilarias of O. gutturosa from the neck of 2. Eight of the horses developed skin reactions 4 to 24 h after the administration of the ivermectin, notably weals over the neck, shoulders and flanks and pitting oedema of the ventral midline and intermandibular s...
Marais J, Masty J.Scanning-electron-microscopic examination of corrosion casts was used to investigate the microcirculation of the coronary border of the equine hoof. Numerous peg-shaped capillary plexuses derived from arterioles extended distally from the dorsal branches of the digital arteries parallel to the hoof wall. The plexuses varied in length and consisted of a fine network of interconnected capillaries that converged to join a centrally situated venule. These centrally situated venules within the papillary plexuses gave rise to a vast venous plexus deep to the coronary band.
Perryman LE, Liu IK.Nine foals with combined immunodeficiency were given hepatic and thymus cells from 68- to 110-day-old (gestational age) fetuses or peripheral blood lymphocytes from nonrelated horses. Clinical signs and lesions consistent with graft vs host reaction were observed in eight of the foals. Diarrhea was observed in these 8 foals, and ulcerative dermatitis, stomatitis, or glossitis was detected in 6 of the 8 foals. Histopathologic changes consisting of necrosis and lymphocyte infiltration were observed in liver, skin, alimentary tract, and less frequently in lymphoid tissues. Changes in complete blo...
Grier-Lowe CK, Anthony J.Equine odontoclastic tooth resorption and hypercementosis is a rarely reported condition in the incisor and canine teeth of older horses. Histologically, there is internal and external resorption of the tooth with formation of excessive cementum. Once lesions become infected or supragingival this condition is very painful. The clinical manifestation, diagnosis and treatment of hypercementosis in an Arabian mare are described. La résorption dentaire odontoclasique et l’hypercémentose représentent une affection rarement signalée des dents incisives et canines chez les chevaux âgés. Sur ...
Nishita T, Anezaki R, Matsunaga K, Orito K, Kasuya T, Sakanoue H, Matsunaga A, Arishima K.Although endoscopy is the definitive diagnostic method for the detection of colonic ulcers, the equipment required for performing the test is costly and difficult to use. Therefore, a simple cost-effective and reliable screening test for intestinal tract bleeding is needed. To this end, we measured carbonic anhydrase isozymes (CA-I and CA-II) originating from erythrocytes by ELISA in order to determine if they could be used as markers of occult blood in feces. For fecal extract preparation, 2 g of feces were mixed with 4 ml of 0.01 M Tris-HCl (pH 8.0) containing 0.01% thimerosal. The concentra...
Cox JE, Jawad NM.The authors describe the short and long term effects of synthetic adrenocorticotrophin and of cortisol on peripheral plasma testosterone concentrations in 2 stallions. A single injection of either hormone temporarily raised plasma testosterone concentrations but repeated injection (twice daily for 5 days) depressed plasma testosterone concentrations. Cessation of treatment was followed by a rise in plasma testosterone to concentrations higher than those in the pretreatment period. These findings are briefly discussed.
Rastegaev IuM.Alongside with a high intensity of infection of horses with botfly larvae there was observed mass aberrant parasitism of horse botflies in farms of Astrakhan, Guryev and Uralsk Provinces, and in the Kalmyk ASSR in 1980-1981 and 1987. As a result of extremely high aggregation of horse botfly larvae in their usual localization places, Gasterophilus pecorum larvae remained, due to interspecific competition, in nonspecific places (oral cavity, pharynx), adapted to new habitats and normally developed. Their number varied from 260 to 750 specimens. Localization of G. pecorum larvae in the mentioned ...