"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.
Ebisawa I, Takayanagi M, Kigawa M.Clostridium tetani was isolated from human and animal stools at the following rates [95% confidence interval (CI)]: Human, 0% (1.5-0); horse, 1% (5-0); cow in cowshed, 4% (10-1); cow in pasture, 8.3% (17-1), calf in pasture, 0% (7-0); dog, 2% (11-0) and sheep in pasture, 25% (44-14). Quantification of C. tetani in 16 animal stools positive for the bacillus was impossible in most cases, as the number of tetanus bacilli present was not large enough for this purpose. Contaminating anaerobic and facultative anaerobic bacteria in human and animal stools, i.e., C. perfringens and Streptococcus sp., ...
Nickels FA.This article discusses the complications of castration and ovariectomy and their treatment and prevention. These two procedures were chosen because castration is the most common surgical procedure performed by the equine practitioner and ovariectomy is associated with a high number of complications.
Trotter GW.Surgical exploration of the horse that has presumably had a normal castration or a previously successful cryptorchid surgery remains a distinct challenge. No hard and fast rules dictate a proper course of action for each case. If a horse was anesthetized for routine castration, discovered to have only one scrotal testis, had a brief exploratory on the nondescended side and was recovered, trauma to the inguinal region would probably be sufficiently minimal that an inguinal approach could be used at subsequent exploratory surgery. If the inguinal canal was extensively manipulated and the tail of...
Kayar SR, Hoppeler H, Mermod L, Weibel ER.Individual mitochondria were reconstructed from ultrathin serial sections of selected muscle fibers in the M. semitendinosus of a horse, over a length of nearly two sarcomeres. Mitochondria were found to be highly variable, with size and complexity of single mitochondria increasing with the fractional part of a fiber occupied by mitochondria. In fibers with a mitochondrial volume density of less than 4%, corresponding to the mitochondrial content of fast-twitch glycolytic fibers, mitochondria were generally rather simple cylindrical shapes, oriented parallel to the myofibrils. In fibers with a...
Owen RA, Jagger DW, Quan-Taylor R.The prevalence of Anoplocephala perfoliata in 103 horses and ponies from Clwyd, Powys and the adjacent English marches, slaughtered during January 1987, was 69 per cent.
Clark ES, Morris DD, Allen D, Tyler DE.A yearling Hanoverian filly had intermittent colic for 6 weeks, chylous peritoneal effusion, and a firm mass palpable per rectum. Exploratory laparotomy revealed mesenteric lymphadenopathy, adhesion of the mesenteric root to the duodenum and jejunum, distention of the mesenteric veins and lymphatic vessels, and increased jejunal venous pressure. Lesions in the duodenum, jejunum, and colon included infiltration of lymphocytes and plasma cells in the lamina propria.
Harrison IW, Raker CW.Review of medical records of 78 horses admitted to the George D. Widener Hospital for Large Animals with dorsal displacement of the soft palate revealed 94% of these horses to have evidence of an intermittent abnormal "gurgling" respiratory noise at the time of exercise. Sternothyrohyoideus myectomy was used as a primary treatment for 17 of these horses, with a success rate of 58%. Anatomic dissection of 30 horses indicated that the midcervical region is the optimal site for sternothyrohyoideus myectomy to alleviate dorsal displacement of the soft palate.
Vaala WE, Clark ES, Orsini JA.Gram-negative neonatal septicemia was diagnosed in a premature Standardbred colt. Clinical signs included lethargy, weakness, loss of suckle reflex, tachypnea, and injected mucous membranes. Sequelae included pneumonia, omphalophlebitis, septic arthritis, and osteomyelitis. Prepartum maternal uterine infection, premature delivery, abnormal parturition with premature fetal membrane separation, and failure of passive transfer of colostral immunoglobulins increased the foal's risk for developing sepsis. Treatment included administration of moxalactam disodium and cefadroxil. The clinical efficacy...
Honnas CM, Ragle CA, Meagher DM.The medical records of 16 horses with necrosis of the collateral cartilage of the distal phalanx were reviewed. Typical history included a laceration or puncture wound over the affected cartilage, resulting in persistent drainage proximal to the coronary band. All horses had signs of lameness. The duration of drainage prior to admission to the hospital ranged from 5 days to 5 months. The involved cartilages were left front lateral (n = 4), right front lateral (n = 5), left rear lateral (n = 1), right rear lateral (n = 4), left front medial (n = 1), and left rear medial (n = 1). The affected ca...
Boosman R, Németh F.Impairment of the microcirculation in the distal part of the foot is an important factor in the aetiology of equine laminitis. To prevent the development of chronic laminitis and the resulting complications, two new therapeutical principles were tested in the treatment of acute laminitis. Thrombosis which frequently occurs in the corium of the foot, could be controlled by administration of anticoagulants such as heparin. Alpha-receptor blocking agents such as phenoxybenzamine were used, to improve the peripheral blood flow. The use of these drugs and that of anti-inflammatory agents during the...
Mutsaers CW, van der Velden MA.Within a one-year period two ponies were operated on because of colon impaction. The two ponies had each been treated with Amitraz (Taktik) quite recently. In view of findings reported in the literature, the colon impaction in these two ponies was very likely to have been due to treatment with Taktik.
Kiper ML, MacAllister C, Qualls C.A cranial mesenteric arterial aneurysm with fistulous tracts to the cecum and ileum was discovered in a Missouri Fox Trotter stallion. The principal clinical sign was hematochezia, observed at 7- and 10-day intervals. The lesion may have been attributable to arteritis caused by fourth-stage larvae of Strongylus vulgaris.
Waelchli RO, Ehrensperger F.Hydrops allantois was diagnosed in two Haflinger mares with severe abdominal distension. Both mares were seven months pregnant. Abortion was induced with two injections of prostaglandin six hours apart followed by further manual dilation of the cervix and administration of oxytocin the next day. There were 90 and 95 litres of fluid, respectively, in the allantoic cavities which resembled extracellular fluid with regard to concentrations of urea, creatinine, sodium, potassium, calcium, magnesium, phosphate and chloride, but not total protein. Both fetuses had severe brain abnormalities which we...
Alvinerie M, Houin G, Toutain PL.The binding of prednisolone to total plasma proteins of dogs, horses, cows, and sheep was characterized using equilibrium dialysis. Prednisolone was bound to a first protein with high affinity but low capacity (transcortin) and to a second protein according to a nonsaturable mechanism (albumin). Interspecies differences were observed, with cows and dogs exhibiting the lowest, and sheep and horses the highest specific binding capacities. The results are in good agreement with known pharmacokinetic properties of prednisolone in domestic species.
Lyons ET, Tolliver SC, Drudge JH, Swerczek TW.Oxfendazole paste formulation was administered intraorally at a dosage of 10 mg/kg of body weight, twice (48 hours between treatments) in 5 controlled tests (experiments A, B, C, D, and E) to 18 equids (14 horses and 4 ponies) that were 5 to 24 months old in 1986 and 1987. Activity was evaluated against naturally acquired infections of various internal parasites, with emphasis on migratory stages of Strongylus vulgaris and S edentatus. The number of treated and nontreated equids in each experiment (horses in experiments A to D and ponies in experiment E) was: A, 1 and 1; B, 3 and 3; C, 3 and 1...
Brown CC, McClure JJ, Triche P, Crowder C.Excisional biopsy specimens were received from 8 horses with lesions suspected of being caused by Pythium sp. Pythium sp was isolated from all specimens. An indirect peroxidase technique was applied to formalin-fixed tissues from the biopsy material and there was distinct staining of hyphal cell walls in all specimens. Sections containing hyphae, other than those of Pythium sp, failed to stain. The indirect peroxidase technique could be used for confirmation of suspected cases of pythiosis.
Gottlieb M, Essén-Gustavsson B, Lindholm A, Persson SG.Circulatory and muscle metabolic responses were studied in 10 horses which all performed incremental draught work at a low trotting speed on a treadmill (D-test) and also exercise with gradually increasing velocities (S-test). Exercise was continued until the horses could no longer maintain the weights above the floor or maintain speed trotting without changing gait to a gallop. Muscle biopsies were taken from the gluteus and the semitendinosus muscles before, and immediately after, exercise. The heart rate (HR) increased linearly with both increasing draught resistance and velocity and reache...
Blackburn NK, Swanepoel R.Tests for neutralising (NT) antibodies to the nine serotypes of African horse sickness (AHS) virus on the sera of three groups of horses confirmed that an increasing number of immunisations with vaccine containing attenuated strains of serotypes 1 to 6 of the virus, leads to broader response to the various serotypes and to higher individual titres. Nevertheless some horses failed to respond to one or more serotypes despite receiving numerous immunisations and it was clear that vaccine containing only serotypes 1 to 6 could not be relied upon to induce adequate cross-immunity to serotypes 7 to ...
Hall RF, Pursell AR, Cole JR, Youmans BC.An epizootic of equine infectious anemia (EIA) involved 35 horses on a farm in south Georgia. During a 126-day period, 21 of these horses became seropositive for EIA. After the initial diagnosis in July, the horses were tested every 7 to 10 days. At least one additional horse was found to be seropositive on each testing day. As soon as they were determined to be seropositive, the horses were removed from the herd and sent to slaughter. The removal of the seropositive horses, however, did not stop the epizootic. We believe the initial infection was from a 7-year-old stallion that recently had b...
Sullins KE, McIlwraith CW, Yovich JV, MacHarg MA, Fessler J.Unilateral ureteral ectopia was diagnosed in three-year-old and 10-month-old fillies exhibiting urinary incontinence since birth. In one case reimplantation of the ureter onto the bladder was planned but considered to be impractical intra-operatively. Unilateral nephrectomy was performed successfully in both cases which alleviated the urinary incontinence. Both horses had normal urinary function postoperatively and became healthy, serviceable animals.
Soma LR, Behrend E, Rudy J, Sweeney RW.The disposition of flunixin meglumine administered IV at a dosage of 1.1 mg/kg was described by a 2-compartment model; the alpha and beta half-lives (t1/2) were 0.61 and 1.5 hours, respectively. When administered IV at a rate of 2.2 mg/kg, the disposition was best described by a 3-compartment model, and the alpha, beta, and lambda t1/2 were 0.16, 1.52, and 6.00 hours, respectively. The zero-time plasma concentrations after flunixin meglumine was administered at 1.1 and 2.2 mg/kg were 9.3 +/- 0.76 and 21.5 +/- 7.4 mg/L, respectively. The bioavailability after oral administration of 1.1 mg/kg wa...
Rott R, Herzog S, Richt J, Stitz L.Borna disease is an endemic progressive encephalomyelitis of horses and sheep prevalent in central Europe. A wide variety of animal species, ranging from chickens to primates can be infected experimentally with the causative virus, which is only poorly characterized. Furthermore, BD virus-specific antibodies have been detected in sera and cerebrospinal fluids of psychiatric patients. Our studies on the pathogenesis of BD have shown that-at least in rats-the disease is not caused by the infecting virus itself, but by a virus-induced immunopathological reaction. Thus, after intracerebral infecti...
Watson ED, Stokes CR.Immunoglobulins A, G and M were localised by immunoperoxidase staining of endometrial sections from ovariectomised mares. Treatment with progesterone or oestradiol-17 beta did not significantly affect numbers of cells secreting any of the isotypes. Mares with persistent endometritis did not have significantly greater numbers of endometrial plasma cells than genitally-normal mares.
Kelly CM, Hoyer PB, Wise ME.Dispersed horse luteal cells were used to evaluate the ability of horse LH, hCG and PMSG to stimulate progesterone secretion in vitro. Morphological characterization of these cells before gonadotrophin stimulation indicated the presence of two populations of cells based on cell diameters. In luteal cells incubated as suspended cells, horse LH and hCG stimulated (P less than or equal to 0.05) progesterone production at all levels of treatment. Stimulation of progesterone secretion by hCG was greater (P less than or equal to 0.05) than by horse LH over the range of concentrations utilized. When ...
Dyke TM, Hubbell JA, Grosenbaugh DA, Beard W, Mitten L, Sams RA, Hinchcliff KW.The pharmacokinetics of furosemide were investigated in anaesthetized horses with bilateral ureteral ligation (BUL) with (n = 5) or without (n = 5) premedication with phenylbutazone. Horses were administered an intravenous (i.v.) bolus dose of furosemide (1 mg/kg) approximately 60-90 min after BUL. Plasma samples collected up to 3 h after drug administration were analysed by a validated high performance liquid chromatography method. Median plasma clearance (CLp) of furosemide in anaesthetized horses with BUL was 1.4 mL/min/kg. Apparent steady state volume of distribution (Vd(ss)) ranged from 1...
Watson ED, McDonnell AM, Cí·¯ord D.The characteristics of the cyclicity of 12 maiden thoroughbred mares kept in two groups were studied over a total of 58 cycles. On average, oestrus lasted 5.3 days and in 60 per cent of the cycles ovulation occurred in the last two days of oestrus. Oestrus and ovulation tended to be synchronised in each group of mares. The mean diameter of single-ovulating preovulatory follicles on the day before ovulation was 41.5 mm and during the seven days before ovulation they grew 2.5 mm/day. More than one follicle ovulated in 19 (33 per cent) of the cycles (seven double ovulations and 12 dioestrous ovul...
Karlström K, Essén-Gustavsson B.An assumed link between red cell hypervolaemia, an excessive amount of training and impaired performance of hypervolaemic horses has led to a theory that the muscle fibres could be affected. Myosin heavy chain (MHC)-based fibre type composition in gluteus medius muscle of red blood cell normo- (NV) and hypervolaemic (HV) Standardbred trotters was evaluated using immunohistochemistry. Muscle biopsies were obtained from 13 NV and 16 HV horses. Serial transverse sections were cut and reacted with antibodies against different isoforms of the myosin heavy chains MHCI, MHCIIA and MHCIIX. Sections we...
Eagle MT, Koch DB, Whalen JP, Hintz HF, Krook L.The left thoracic limb was immobilized in a plaster cast in 6 grade weanling ponies for 6 weeks. Two ponies were injected intramuscularly each day with 2.4 micrograms of 25-hydroxycholecalciferol [25(OH)D3] per kg bodyweight, two with 1.2 micrograms and two received no injections. Immobilization of 25(OH)D3 treatment had no significant effect on mineral metabolism. Immobilization resulted in significantly decreased weight and specific gravity of metacarpus III (MCIII). Histologic examination and triple fluorochrome incorporation showed that the osteopenia was caused by atrophy of osteoblasts w...
Dusek J, Munk Z.The study was based on the documentation of the Napajedla Stud Farm of the English Thoroughbred horse for 1888-1972. Evaluating the effect of the age of stallions on their fertility (leaving aside the variability of the age of their mothers), such an effect was found to be significant only in four out of the 26 studs evaluated. In 65% of the selected stallions, the correlation coefficients were found to be negative, but without statistical significance. However, the objective of the study was to evaluate stallions and mares parallelly as to their age variability and fertility. The relationship...
Rose PL, Auer JA, Hulse D, Hightower D, Schenk RK.beta-Tricalcium phosphate (TCP) was evaluated as a synthetic bone grafting material in horses. Sixteen horses were randomly assigned to 4 groups of 4 horses. In each horse, an 11-mm by 10-mm circular defect with a smooth margin was created surgically in the weight-bearing surface of both third metacarpal bones (McIII) and the left third metatarsal bone. The defect in the left McIII was filled with TCP, the defect in the right McIII was filled with a mixture of 50% autogenous cancellous bone (ACB) and 50% TCP, and the defect in the left third metatarsal bone was not filled to serve as a control...
Mariani LPR, Sampaio F, Silveira AB, Bastos LF, Weber SH, Michelotto PV.Diseases of the stifle joint remain a challenge for veterinarians. The objective of this study was to achieve a valuable acupuncture suggestive diagnosis to be considered for stifle joint diseases in horses. Thirty-nine nonlame horses involved in different activities were assessed. Acupuncture was independently performed by two evaluators. Reactions of the animal when pressurizing the point suggestive of stifle disease (PSSD), Bladder-20 and/or Bladder-21, were considered as the inclusion criteria for inclusion in the stifle group (SG, n = 31), and the animals with no reactions were assigne...
Hoff TK, Hood DM, Wagner IP.To evaluate the clinical efficacy of topically administered glyceryl trinitrate (GTN) for inducing digital submural vasodilation in clinically normal horses. Methods: 7 adult horses without foot abnormalities. Methods: A concurrent-control crossover design was used to determine whether topical application of GTN ointment for prevention or treatment of laminitis would result in a detectable increase in digital perfusion. Heat-acclimated horses instumented for detection of wall surface temperature (HWST), mean systemic pressure, and heart rate were used. Horses were exposed to cold to induce dig...
Cornick JL, Carter GK, Bridges CH.Chronic hepatic disease was diagnosed in 6 horses with history of anorexia and weight loss. These horses consistently had abnormally high serum gamma-glutamyltransferase activities, total and direct bilirubin and blood ammonia values, and sulfobromophthalein clearance times, whereas serum iditol dehydrogenase, aspartate transaminase, and alkaline phosphatase activities were variable. In the 6 horses, histologic examination of the liver revealed lesions of chronic hepatitis with varying degrees of fibrosis. All 6 horses had ingested kleingrass (Panicum coloratum) for variable periods. Three hea...
Apukhovska LI, Vendt VP, Ivashkevych SP.Sterols of the whole erythrocytes, hemoglobin, membranes and their protein fractions were studied. Erythrocytes and their components were established to contain, besides cholesterol, other substances of the sterol nature. Cholesterol, 7-dehydrocholesterol and other substances of the cholesterol series are practically completely linked with the lipoproteid fractions of the erythrocyte membrane whereas all sterols found in the native erythrocytes in negligible amounts are bound with hemoglobin.
Tremelling AM, Marley RA, Marley MB, Woofter CM, Docherty C, Salvator AE, Muakkassa FF.Many Americans sustain large animal-related injuries (LARIs) from blunt trauma. We compare the injuries and management of LARI in our region of the United States with those of motor vehicle crashes (MVCs). Methods: A 15-year retrospective study of trauma patients with LARI matched to MVC controls by Injury Severity Score (ISS), age, and sex was conducted. Values were statistically compared, and differences were considered statistically significant at P < .05. Results: There were 156 LARI cases, of which 87% were related to horses, 8% to bulls, and the remainder to deer, mules, bison, cows, ...
Van Camp SD, Mahler J, Roberts MC, Tate LP, Whitacre MD.An ovarian adenocarcinoma with teratomatous elements was removed from a 9-year-old mare. Although no other lesions were detected at ovariectomy, multifocal metastatic masses led to cachexia and euthanasia 2 months later. This case reaffirms the need to exercise caution when removing ovarian masses to prevent seeding of the abdomen. This report includes discussion of the WHO system of classification of ovarian tumors.
Hrudka F, Betsch JM, Kenney RM.Anomalies of centriolar derivatives were identified in ejaculates and testicular and tracheal biopsies of a sterile stallion, using light, scanning, and transmission electron microscopy. LM revealed that over half the sperm population had only a vestigial or no tail, while the rest had tails of variable length and shape. The vestigial tail was represented by its anlage, which was implanted on the nucleus and differentiated up to capitulum and collum stage. The stunted tail had an axoneme and its derivatives, but was short in all tail segments. Regardless of the tail length or shape, virtually ...
Honoré ML, Pihl TH, Busk-Anderson TM, Flintrup LL, Nielsen LN.D-dimer has value as a marker of thrombosis in critically ill horses and can provide additional information about prognosis. However, there are currently no equine species-specific d-dimer assays available, nor has there been any formal investigation of the applicability of human d-dimer assays in horses, so it is unknown, which assay performs best in this species. The aim of this study was therefore to evaluate and compare two human d-dimer assays for their applicability in horses. The study included four groups of horses: clinically healthy horses, horses with gastrointestinal (GI) disease a...
Martín-Cuervo M, Aguirre CN, Gracia LA, Barrera R, Ezquerra LJ, Martinez-Subiela S, Cerón JJ.Point-of-care (POC) systems for the joint measurement of Troponin and D-dimers have not been studied in horses. The aim of this study was to perform the validation of a POC system (AQT90 FLEX) for the measurement of cardiac troponin I (cTnI) and D-dimers in the serum of horses with gastrointestinal diseases. The main objective was to evaluate whether or not this system can distinguish healthy animals from diseased animals. A sample of 33 horses was included in the study: control group (n = 10) and horses with gastrointestinal disorders (n = 21), which were classified according to their outco...
Beech J, Fletcher JE, Tripolitis L, Lindborg S, Dawso T.The contractile activity, the threshold for calcium-induced calcium release in fractions of sarcoplasmic reticulum and the potassium concentration were determined in preparations of semimembranosus muscle from normal quarter horses and quarter horses with hyperkalaemic periodic paralysis before and after they were treated with phenytoin. Before the treatment there was no difference in caffeine contracture or electrically elicited twitch response between the two groups. For one week after the treatment, the time to peak tension of caffeine contractures was significantly (P < 0.005) reduced i...
Lothrop CD, Henton JE, Cole BB, Nolan HL.Serum prolactin concentration was determined before and after TRH administration to normal mares at 10 months of gestation, 2 and 4 months post partum and during a -7- to +14-day peri-parturient period. The serum prolactin concentration increased significantly (P less than 0.05) at 15, 30 and 60 min after TRH administration in the normal mares regardless of the season of the year, pregnancy or lactation status. However, during the periparturient period, the basal prolactin concentration was increased 4-fold and there was only a marginal increase after TRH administration. Of 9 agalactic mares, ...
Gunther JD, Foley CW, Gaverick HA, Plotka ED.Progesterone concentrations were measured in milk and blood plasma for 15 mares throughout a normal estrous cycle and early pregnancy to determine the feasibility of utilizing progesterone in milk as an indicator of pregnancy. Samples were obtained daily from foaling until diagnosis of pregnancy by rectal examination at 30 to 35 days of gestation. Progesterone in milk and blood plasma was quantified by radioimmunoassay. Mean progesterone concentrations (+/- SE) in plasma from foaling to foal heat and during estrus, luteal phase and pregnancy were .51 +/- .09 ng/ml, .53 +/- .08 ng/ml, 3.88 +/- ...
Baker E, Geick A, Hines M, Gerhold R, Cordero-Aponte C.A 17-year-old female grade pony presented to University of Tennessee Veterinary Medical Center in May of 2021 for evaluation of multifocal, firm, sessile, circular lesions of various diameters on the ventrum and flank. The lesions had been present for two weeks at presentation. An excisional biopsy found numerous adult and larval rhabditid nematodes most consistent with Halicephalobus gingivalis. PCR targeting a portion of the large ribosomal subunit confirmed this diagnosis. The patient was treated with a high dose course of ivermectin followed by fenbendazole. The patient began showing neuro...