"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.
Paradis MR, Breeze RG, Laegreid WW, Bayly WM, Counts DF.Eight ponies were allotted to 2 groups of 4. Group-1 ponies (1-4) were given 0.2 g of indole/kg of body weight orally and group-2 ponies (5 to 8) were given 0.1 g of indole/kg. Various physical, hematologic, and physiologic measurements were obtained after administration of indole. Intravascular hemolysis and hemoglobinuria were detected in both groups within 24 hours of dosing. Hemolysis was reflected by decreases in PCV, hemoglobin concentration, and RBC count, and an increase in indirect bilirubin. Erythrocyte fragility appeared to increase in both groups at 8 hours after dosing and peaked ...
Whitwell KE.An autopsy study of one dead and two sick hares from an East Anglian estate on which two mares had died of grass sickness revealed that two of the hares were suffering from a polyganglionopathy and alimentary tract changes, remarkably similar to those seen in grass sickness in horses. No such abnormalities were found in two healthy hares from the same locality.
Buckingham SH, Jeffcott LB.Methods for the non-invasive assessment of bone quality were used to monitor the osteopenia induced by immobilising a forelimb in a cast. These techniques included the measurement of ultrasound velocity, single photon absorptiometry and radiographic photodensitometry. Serial measurements were made before, during and after an eight week period of immobilisation of the left forelimb of four adult standardbreds in a light fibreglass cast which included the foot and extended above the carpus. The measurements continued for 12 weeks after the removal of the cast. The results indicated a trend to de...
Baird AN, Cohen ND, Taylor TS, Watkins JP, Schumacher J.During a 5-year period, renosplenic entrapment of the large colon was diagnosed in 57 horses referred to the Texas Veterinary Medical Center. The signalment of and clinical signs of disease in these horses were compared with such variables in 200 horses referred for other types of colic. Findings did not support a male gender predilection for this disease, as was previously reported. The case survival rate was 93% for this group of horses. Fourteen of the horses were treated nonsurgically by rolling them clockwise while they were under general anesthesia. Data supported the safety and efficacy...
de Vries PJ, Zandee AR.As part of the veterinary surveillance of horse breeding management, the veterinarian is increasingly often requested to predict ovulation and to give a breeding or insemination advice accordingly. The result of a teasing procedure is indispensable for this advice. A suggestion is made for the quantification of oestrus signs. Oestrus symptoms are classified into four categories. In addition, various factors are mentioned, which affect the result of a teasing procedure.
Edwards JF, Ruoff WW.Cecal rupture has been reported as a complication of tape-worm infestation or parturition in horses. Often it occurs with no apparent predisposing factors. Spontaneous rupture on the medial surface of the cecum occurred in 2 of 19 foals, 12 to 24 hours after gastric endoscopy. The sites of rupture were identical in both foals. Rupture occurred despite prior deworming, withholding of food and water before anesthesia, and care in induction of anesthesia and recovery. Surgeons should be aware of the potential of cecal rupture in horses anesthetized for elective surgery.
Moll HD, Juzwiak JS, Santschi EM, Slone DE.Volvulus of the small intestine was diagnosed as a complication of acquired inguinal herniation in 2 horses. One of the horses continued to have signs of pain after reduction of the hernia. The volvulus was diagnosed at a second surgery, but the intestine was devitalized, and the horse was euthanatized. Ventral midline exploratory surgery was performed on the second horse, in conjunction with an inguinal approach. The small-intestinal volvulus was diagnosed and corrected at this time. It is suggested that ventral midline abdominal exploration be performed when acquired inguinal herniation caus...
Houpt KA.The value of behavioral techniques in assessing animal welfare, and in particular assessing the psychological well being of animals, is reviewed. Using cats and horses as examples, 3 behavioral methods are presented: (1) comparison of behavior patterns and time budgets; (2) choice tests; and (3) operant conditioning. The behaviors of intact and declawed cats were compared in order to determine if declawing led to behavioral problems or to a change in personality. Apparently it did not. The behavior of free ranging horses was compared with that of stabled horses. Using two-choice preference tes...
Thompson DL, Garza F, St George RL, Rabb MH, Barry BE, French DD.Thirty-five ovariectomized pony mares were used to study the relationships among luteinizing hormone (LH), follicle stimulating hormone (FSH) and prolactin (PRL) concentrations in blood (secretion), in pituitary (storage) and in blood after secretagogue administration, as well as the content of gonadotropin releasing hormone (GnRH) in hypothalamic areas, under various conditions of steroidal and nonsteroidal treatment. Five mares each were treated daily for 21 d with vegetable shortening (controls), testosterone (T; 150 micrograms/kg of body weight, BW), dihydrotestosterone (DHT; 150 microgram...
Freeman DE, Donawick WJ.Mucosa obtained from the cecum of healthy horses and incubated in vitro with 0.1 mM cycloleucine could accumulate this amino acid against an apparent concentration gradient after 60 and 120 minutes. Accumulation by the serosal (antiluminal) surface of the tissue was 3 times greater than accumulation by the mucosal (luminal) surface after 120 minutes (P less than 0.001). Cycloleucine accumulation was significantly reduced by Na deprivation after 60 minutes (P less than 0.05) and 120 minutes (P less than 0.01) and by anoxic conditions after 120 minutes (P less than 0.05). Transmucosal flux from ...
Byars TD, Becht JL.The historical, clinical, diagnostic, and therapeutic aspects of pleuropneumonia are reviewed with emphasis placed on aggressive treatment and ultrasound diagnosis. The common sequelae are described, and appropriate treatment recommendations are included. A favorable prognosis may be expected for horses receiving long-term treatment.
Tscheuschner R, Richter W, Dietz O, Petersen R.Metacarpal or metatarsal exostoses were diagnosed in 112 horses used for sport purposes between January 1976 to December 1987. Fourteen of these patients were treated surgically by subperiosteal removal of the exostosis. All animals which could be followed up had returned to their original use. The average time of use after discharge from the clinic was 38.4 months. Surgery was successful in completely removing the exostoses in 58.3% of these horses. The indications for anaesthesia and resection of the ulnar nerve are discussed.
Schmotzer WB, Riebold TW, Rowe KE, Scott EA.The steady-state response characteristics of a pulse oximeter were evaluated on intestinal segments of seven clinically normal halothane-anesthetized horses. Arterial oxygen tension greater than 200 mm of Hg, end tidal carbon dioxide from 30 to 35 mm of Hg, and systemic mean arterial pressure greater than 70 mm of Hg were maintained throughout the recording periods. Values for percentage of pulse oximeter oxygen saturation, pulsatile blood flow, and percentage of signal strength were recorded from jejunum, ileum, cecum, left ventral colon, left dorsal colon, and descending colon. Probe placeme...
Hoffman AM, Staempfli HR, Prescott JF, Viel L.A double-blind randomized clinical trial was undertaken to determine the value of parenterally administered Streptococcus equi M-protein vaccine in foals during an epizootic of strangles. Weaned mixed-breed foals (n = 664) housed on 2 adjacent feed-lots (A and B) arrived over a 5-day period, 2 weeks before primary vaccination. Foals in lot B (n = 114) were randomly administered vaccine (n = 59) or saline solution (placebo; n = 55) on 3 occasions at biweekly intervals. Foals in lot A (n = 450) were given 1 dose of vaccine (n = 225) or placebo. The following clinical observations were scored bli...
Dean PW.Abnormalities of the nasal cavity, pharynx, larynx, and trachea result in respiratory noise and exercise intolerance. Clinical features of common upper respiratory conditions of performance horses are reviewed with emphasis on diagnosis, treatment, and risk factors that affect the outcome of surgical treatment.
Schuberth HJ, Hadam M, Leibold W.The determination of differentiation and transplantation antigens will be of growing importance in immune diagnosis for individual animals as well as for breeding purposes in populations. Differentiation antigens characterize subsets of cell populations and indicate their functional capacity while transplantation antigens represent markers of individuals of a species. Occurrence and significance of these antigenic systems are briefly reviewed.
Stewart F, Tuffnell PP.A 514 bp cDNA transcript coding for 78% of horse (Equus caballus.) GH has been cloned and sequenced. The deduced amino acid sequence corresponded precisely to that previously obtained by protein sequencing and, in addition, provided new sequence information for the signal peptide. The missing 3' fragment of the cDNA was reconstructed using synthetic oligonucleotides and site-specific directed mutagenesis. The complete cDNA sequence was then inserted into an expression vector (PIN-III-lppp-5) which utilizes a bacterial signal peptide to secrete the expressed product into the periplasmic space o...
Takeda A, Suzuki E, Kamei K, Nakata H.Several kinds of loline-type alkaloids, norloline, loline, N-acetylnorloline, N-acetylloline, N-formylnorloline, N-formylloline and N-methylloline were detected in the urine of race-horses. Furthermore, a new compound of the alkaloids, N-senecioylnorloline, was also found and identified. These compounds were mainly identified by means of gas chromatography-mass spectrometry (GC-MS) and gas chromatography-fourier transform-infrared spectrometry (GC-FT-IR). A certain plant of Gramineae containing four kinds of loline-type alkaloids was found in a bale of hay used for the horse forage. The taxono...
Bocklisch H, Ludwig C, Lange S.Between 1982 and 1989 59 equine fetuses were investigated for chlamydiae using animal experiments and embryonated eggs. Chlamydiae were isolated from 16 fetuses (27.1%) originating from 8 studs. The macroscopical lesions of the fetal organs were characterized by extensive haemorrhages. The histological picture shows severe lesions of the blood vessels of different organs. In 6 studs in which chlamydiae had been isolated, blood sera of clinically healthy and pregnant mares were investigated for antibodies during 1989 and 1990. Antibody titres between 1:10++ and 1:40 were detected by using compl...
Embertson RM.Upper respiratory tract conditions of the older horse that are not necessarily associated with athletic exercise intolerance are discussed. Some of the diseases described include ethmoid hematoma, sinus disease, guttural pouch empyema and mycosis, retropharyngeal abscess, nasopharyngeal cicatrix, arytenoid chondropathy, and neoplasia.
Nikles SA, Heath TJ.The intestine of horses differs from that of most other domestic animals in having a huge ascending colon and cecum, which together act as a large fermentation vat. The lymph drainage from this intestine occurs through a complex network of lymph vessels and lymph nodes, of which there are several thousand. The pathways taken by lymph through these vessels and nodes were studied by tracing injections of dye, by examining Microfil casts, and with light and transmission electron microscopy. Lymph vessels transporting lymph from the intestinal wall generally terminate on a single node within a gro...
Morris DD, Henry MM, Moore JN, Fischer JK.A study was conducted to determine whether dietary supplements with alpha-linolenic acid altered the ability of equine peritoneal macrophages to produce tumor necrosis factor (TNF) in response to endotoxin. Peritoneal macrophages were harvested from 6 healthy adult horses before and after the horses were fed a nutritionally balanced ration that contained 8% linseed oil as a source of alpha-linolenic acid. The macrophages were cultured in media containing no additives (control), endotoxin (0.5 to 50 ng/ml), or the calcium ionophore, A23187. Macrophage supernatants were collected after 6 and 24 ...
Reed SM, Robertson JT.This article reviews recent diagnostic procedures that have arisen over the last 10 years. Videoendoscopy of horses on a high-speed treadmill allows observation of some of the changes that take place in a horse's airway during exercise. Measurements of upper airway airflows and transupper airway pressure, the use of an esophageal balloon and a Ventigraph to measure changes in pleural pressure, and pulmonary function testing are new techniques that aid the researcher in understanding the mechanics and pathologic characteristics of airway diseases and help the practitioner in assessing the sever...
Lopez MJ, Robinson SO, Cooley AJ, Prichard MA, McGinnis MR.An 18-year-old mare was evaluated for an oral mass that developed after extraction of a broken incisor. Results: An ulcerated, firm, darkly pigmented, approximately 5-cm-diameter spherical mass involved the gingiva lateral and dorsal to the right first to third maxillary incisors. Osteolysis of the roots of the first and second right maxillary incisors and periosteal proliferation of the adjacent premaxilla margins were apparent on radiographs. Histologic examination of the mass revealed multiple coalescing and ramifying foci of abscess formation, each containing a well-defined, discrete, blac...
Court MH, Engelking LR, Dodman NH, Anwer MS, Seeler DC, Clark M.The pharmacokinetics of dantrolene sodium were investigated in horses following both intravenous (2 mg/kg) and intragastric (4 mg/kg) administration. Two ponies also received dantrolene sodium intravenously (2 mg/kg) in a pilot study to obtain preliminary kinetic data and to determine urinary and biliary excretion of the intact drug. Distribution and elimination of dantrolene was rapid, resulting in an elimination half-life of 129 +/- 8 (SEM) min and a whole body clearance of 4.16 +/- 0.52 ml/min/kg. Following intragastric administration, dantrolene rapidly acheived peak concentrations within ...
Stokes SM, Burns TA, Watts MR, Bertin FR, Stefanovski D, Medina-Torres CE, Belknap JK, van Eps AW.Continuous digital hypothermia (CDH) prevents lamellar failure in the euglycemic hyperinsulinemic clamp (EHC) model of laminitis, but the protective mechanisms are unclear. Objective: To determine if CDH inhibits lamellar inflammatory signaling in the EHC model of laminitis. Methods: Eight Standardbred horses. Methods: Prospective experimental study. Horses underwent an EHC, with 1 forelimb treated with CDH and the other kept at ambient temperature (AMB). Horses were euthanized 48 hours after initiation of the EHC and lamellar tissue was analyzed via polymerase chain reaction (pro-inflammato...
Campbell DL, Douglas LW, Ramge JC.Siliconized rubber tubes were used to cannulate one oviduct in 7 mares, and secretions were collected in a polycarbonate container located externally, in the region of the left paralumbar fossa. Secretion rates were recorded daily during the estrous cycle. Concentrations of calcium, magnesium, sodium, potassium, inorganic phosphorus and glucose were determined in the oviduct fluids secreted throughout the estrous cycle. Secretion rates were greatest during estrus (days 1-9), with a significant decrease (P<.01) noted during nonestrus (days 10-21). Concentrations of all constitutents measured...
Hoopes KH, Gradil CM, Vanderwall DK, Mason HM, Sarnecky BA, Davies CJ.There is an urgent need for practical methods of population control (i.e., contraception and/or sterilization) for free-roaming (i.e., "wild" or "feral") horses and burros on Western Public Lands in the United States. The objective of this study was to evaluate the contraceptive efficacy of a novel self-assembling three-part polymer-coated magnetic intrauterine device termed as an intrauterine POD (self-assembling; iUPOD) when there are natural breeding conditions when iUPOD use was managed by veterinary professionals with no prior experience with the device. Six mares were administered an iUP...
Ross MW.To correlate scintigraphic and clinical findings of the metatarsophalangeal joint (MTPJ) in Standardbreds, radiographic findings in horses with confirmed MTPJ lameness, and determine if stress reaction and more advanced bone remodelling occurred in the MTPJ, medical records of 114 Standardbreds admitted between September 1993 and April 1995 in which bone scintigraphy included standing lateral and plantar views of the metatarsophalangeal joint (MTPJ) were reviewed. Images obtained using a large field of view gamma camera were evaluated visually for location, definition and intensity of increase...
Bauer BS.Although not comprehensive of all ocular conditions in the equine species, this article concentrates on various ophthalmic conditions observed in the horse where laboratory diagnostics are recommended. The importance of laboratory diagnostic testing cannot be underestimated with equine ophthalmic disease. In many cases, laboratory diagnostics can aid in obtaining an early diagnosis and determining appropriate therapy, which in turn, can provide a better prognosis. In unfortunate cases where ocular disease results in a blind, painful eye necessitating enucleation, light microscopic evaluation i...
Teeter MG, Arroyo LG, Bakker JD, Hayes MA, Viel L, Runciman RJ.Arterial calcification is found frequently in the pulmonary artery of racehorses, but the aetiology is unknown. Calcification might be associated with increased wall stress due to arterial geometry (shape) and exercise-induced hypertension. Objective: High wall stress levels are found in the regions associated with calcified lesion formation, exacerbated as transluminal pressure increases to levels associated with exercise. Methods: The pulmonary arteries of 5 horses, unaffected by calcification, were dissected and pressurised to resting and exercising physiological transluminal pressures and ...
Coles GC, Borgsteede FH, Geerts S.As a result of a recent European Union meeting on anthelmintic resistant nematodes of farm animals, a list was made of nine proposals for research and five to control anthelmintic resistance. The most important were the need to have standardised and new tests to monitor the development and spread of resistant nematodes in sheep, goats, horses, cattle and pigs, and for education of veterinary surgeons and farmers in the optimal control strategies to be used to delay the development of anthelmintic resistance in nematodes.
Götzen N, Cross AR, Ifju PG, Rapoff AJ.We investigated the microstructural basis of a reduced stress concentration around the primary nutrient foramen of the equine third metacarpus. We quantified the spatial variations of compositional parameters (mineral content, volume fraction, histological architecture, and osteonal trajectories) from microradiographs and polarizing microscopic images of thin sections. These variations in composition and organization in turn cause variations in mechanical properties of cortical bone. We modeled the spatially inhomogeneous anisotropic elastic properties based on the measured compositional param...
Smith IM, Girard A, Corner AH, Mitchell D.Using two known positive equine viral rhinopneumonitis (EVR) sera, conjugates were prepared with fluorescein isothiocyanate and tested for specificity using EVR infected tissue culture cells. The conjugate was then applied to selected tissues from 32 aborted fetuses and foals submitted during a natural outbreak of EVR. Antigen was detected in various tissues by immunofluorescence in 20 cases (62.5%). In 24 cases bovine fetal kidney cell monolayers were inoculated with a pool of lung and liver and EVR virus was isolated from 15 (62.5%). Histological examination of various tissues from 29 cases ...
Davis MS, Murray MJ, Donaldson LL.There are limited methods of assessing pulmonary function in horses at rest. We developed clinical techniques to measure gas exchange efficiency in horses and evaluated 3 groups of horses that were 1) asymptomatic based on auscultation with rebreathing, transtracheal aspirate cytology, and thoracic radiographs (n = 6), 2) asymptomatic at rest but symptomatic with rebreathing (n = 11) and 3) symptomatic at rest (n = 9). Blood samples were obtained from the transverse facial artery and jugular vein. Maximal end-tidal CO2 tension (PETCO2) was measured by an infrared capnograph through a facemask....
Satou K, Nishiura H.To evaluate the partial effects of vaccination against equine Japanese encephalitis (JE) and characterize other prognostic factors based on previous outbreak records in Japan from 1953 to 1960. Methods: Individual case records, which included demographic information, vaccination history, and clinical information (dates of onset, recovery and death, and symptoms), were investigated. The relations between two outcomes, JE death and symptomatic period, and other variables were examined. Results: Of a total reported 803 cases during the observation period, 453 (56.5%) were diagnosed with either se...
Mair TS, Osborn RS.X-ray diffraction crystallography was used to determine the crystalline composition of 18 equine urinary calculi, including stones originating in the kidney, bladder and urethra. Calcium carbonate in the form of calcite was found to be the major component in all calculi examined. Other components commonly found included weddellite and substituted vaterite. Urine deposits from a number of normal horses were also examined. The significance of these findings, as well as those from a number of previous reports, are discussed in relation to the possible aetiology of urolithiasis in the horse.
Medda R, Cara N, Floris G.Ceruloplasmin is a blue copper-containing serum glycoprotein with oxidase activity. It as been proposed that the physiological function of ceruloplasmin involves the oxidation of ferrous iron and its incorporation into apotransferrin. There are several reports demonstrating that ceruloplasmin is made up of multiple chains. Ryden has questioned the multichain structure of ceruloplasmin from human, pig, horse and rabbit sera, arguing that the dissociation observed by previous workers could be attributed to cleavage of labile bands in the protein by enzymatic contaminants present in commercial pr...
Fey K, Jonigkeit E, Moritz A.Equine and canine Cushing's syndrome, both of which are the result of elevated cortisol levels, show some different pathogenetical and clinical features and require different therapeutical approaches. In older horses the equine Cushing's syndrome (ECS) is not uncommon. Nearly all cases result from excessive hormone production in cells of the pars intermedia of the pituitary. Besides elevated levels of adrenocorticotrope hormone (ACTH), high peripheral levels of pro-opiomelanocortin, beta-endorphines and alpha-melanocyte-stimulating hormone can be measured. In middle-aged and geriatric dogs, Cu...
McCluskey BJ, Mumford EL, Salman MD, Traub-Dargatz JJ.Approximately 20 sentinel premises in Colorado were visited quarterly during a 3-year prospective study to investigate the persistence of VS viruses in horses. A survey to assess management practices, health events, animal movements and environmental data was completed at each visit. Collection of serum samples and oral swabs along with a clinical examination of sentinel horses were performed at each visit. Serum samples were tested by 2 or more of 4 available serological tests. The data collected for two years (August 1998 to August 2000) are reported here. During this period there was seroco...
Sykes BW, Furr M, Giguère S.Twelve healthy horses were assigned to treatment or control groups. Treated horses received PGG-Glucan[ED-1] (1 mg/kg, IV) 24 hours prior to peripheral blood mononuclear cell (PBMC) isolation. PBMCs were isolated and incubated in the presence of lipopolysachharide (LPS). At 0, 6, 12, 24 and 48 hours messenger RNA (mRNA) was extracted. Reverse transcription polymerase chain reaction (PCR) was performed and cytokine mRNA expression for tumor necrosis factor alpha (TNFalpha), interleukin 1beta (IL-1beta), interleukin 10 (IL-10) and interferon gamma (IFN-gamma) determined using real time PCR. A si...