"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.
Dean PW, Robertson JT, Jacobs RM.In 7 horses, 4 anastomoses were done in the small intestine in each, using the combinations of synthetic absorbable monofilament and multifilament suture materials with continuous- and interrupted-suture patterns in the serosubmucosal layer of a 2-layer inverting-suture technique. Horses were evaluated 30 days after the operation for adhesion formation, lumen diameter, evidence of chronic obstruction, and suture tract inflammation at the anastomosis. Postoperative obstruction occurred in 5 of the 7 horses, and 6 horses survived. One horse was euthanatized on postoperative day 6 after 48 hours ...
Tithof PK, Rebhun WC, Dietze AE.A linear array 5 mHz ultrasonic scanner was used to diagnose aorto-iliac thrombosis in a 3 year old Standardbred gelding. There are no reports in the literature of utilization of ultrasonography for visualization of an aortic thrombus. The technique is fairly non-invasive, requiring only a rectal examination with a linear array probe. Arteriography is the only other method described for actual visualization of a thrombus. This procedure is technically difficult and highly invasive.
Malinowski K, Johnson AL, Scanes CG.The ability of interrupted photoperiods to induce early estrus and ovulation was examined. Horse mares were exposed to long (16 h light) or short (10 h light), noninterrupted photoperiods, ambient light, or various interrupted photoperiod treatments from December 1 to April 15 (135 d). Follicular development was assessed by rectal palpation and estrous behavior was determined by teasing with a stallion. Serum concentrations of progesterone were used as an indicator of corpus luteum function. Differences among the light treatment groups were compared for the following behavioral and ovarian cha...
Rebhun WC, Shin SJ, King JM, Baum KH, Patten V.Malignant edema (clostridial myositis) was diagnosed in 9 horses with signs of illness that included fever, depression, painful muscular swellings, and toxemia. The infection followed intramuscular injections in 8 horses and developed in a puncture wound in 1 horse. Treatment consisted of surgical fenestration of the involved muscle, high doses of penicillin, nonsteroidal anti-inflammatory agents and analgesics, and supportive fluid therapy. Five horses recovered and 4 died. Those that died had advanced signs of the disease at admission.
Vernon SD, Webb PA.We developed an enzyme-linked immunosorbent assay (ELISA) that was capable of detecting immunoglobulin M (IgM) antibody to vesicular stomatitis virus (VSV) in the sera of experimentally and naturally infected cattle and horses. The detection of IgM in the sera of these animals permitted an estimate of the recency of infection by VSV serotype New Jersey. A VSV serotype New Jersey epizootic strain isolated from a horse and passed once in an Aedes albopictus cell line was used to infect a horse and a calf. Sera from these animals were used to standardize the ELISA. This assay was used to test ser...
McKibbin LS, Paraschak DM.Bone spavin, splint, and fractured splint bone injuries have been treated with varying methodologies at Wheatley Hall Farm Equine Clinic. Cryosurgery is the most successful. With cryosurgery the small, pain-producing afferent C fibers are destroyed, and painful neuromas do not return. Injured sites were cryosurgically treated with liquid nitrogen for a double freeze-thaw period of 45 sec. 5 sec, 45 sec. Before and after treatment comparisons were conducted on study standardbreds. In all three injury groups, results showed that the standardbreds tended to race as well or with improved times and...
Kaneps AJ, Shires GM, Watrous BJ.The use of real-time ultrasound for examination of the bladder was a useful diagnostic aid in 2 cases of cystic calculi. The ultrasound procedure revealed that a firm mass palpated per rectum in the bladder of one horse was a calculus. In the other horse, ultrasound revealed additional small uroliths. To remove the uroliths in both horses, laparocystidotomy via a ventral paramedian approach was chosen because it provided the best access to the bladder lumen. The calculi were analyzed by qualitative chemical analysis and quantitative crystallography. Results differed between analysis methods. C...
Hayes KE, Pierson RA, Scraba ST, Ginther OJ.The morphological changes in ultrasound images of the uterus at various times of the year were characterized in nonbred mares, using a linear-array scanner. The uterus was recorded as having an ultrasonic morphology characteristic of diestrus (uterine score 1, endometrial folds not visible), estrus (score 3, distinct endometrial folds), or an intermediate stage (score 2). In Experiment I, uterine scores for the first ovulatory period of the year were compared to scores for the second period in 23 pony mares. More mares (P<0.05) showed endometrial folding prior to the second ovulation of the...
Halliwell RE, Brim TA, Hines MT, Wolf D, White FH.An enzyme linked immunosorbent assay was developed for the detection of immunoglobulin class specific antibodies to Leptospira interrogans serovar pomona in the serum and aqueous humor of horses. Serum antibody was also assayed by microscopic agglutination tests. Although higher levels of antibody were found in sera from horses with signs of uveitis, the association was not statistically significant. Antibodies to pomona were detected in the aqueous of 12 eyes from the 101 horses sampled at a slaughterhouse, and in most instances, a comparison of the aqueous/serum antibody level with that of t...
Gerken DF, Sams RA.The effects of i.v. chloramphenicol sodium succinate on the pharmacokinetics of i.v. phenylbutazone in six healthy adult horses were investigated. Administration of chloramphenicol sodium succinate to mares reduced mean (+/- SD) phenylbutazone clearance from 0.600 +/- 0.222 to 0.339 +/- 0.123 ml/min per kg and increased mean (+/- SD) half life from 244 +/- 59.8 to 371 +/- 80.8 min and mean residence time from 333 +/- 86.2 to 533 +/- 124 min. The mean steady-state volume of distribution of phenylbutazone was unchanged, with mean (+/- SD) values of 187 +/- 28.9 ml/kg in control animals and 170 +...
Laut JE, Houpt KA, Hintz HF, Houpt TR.In order to determine if horses will increase their intake in response to caloric dilution, four pony geldings were fed ad lib a mixed grain diet either undiluted (3.4 Mcal/kg of digestible energy) or diluted (wt/wt) with 25% sawdust (2.6 Mcal/kg) or with 50% sawdust (1.7 Mcal/kg). The mean daily caloric intake was 17,457 kcal (3.4 Mcal diet), 17,546 kcal (2.6 Mcal diet) and 12,844 kcal (1.7 Mcal). The mean time spent eating was 246 (3.4 Mcal), 351 (2.6 Mcal), and 408 (1.7 Mcal) minutes/day. Meal size increased and meal frequency decreased with increasing dilution. The median long survivorship...
Seal US, Siniff DB, Tester JR, Williams TD.Combinations of etorphine hydrochloride and xylazine hydrochloride in different dosages were tested for their efficacy as immobilizing agents on 16 recently captured feral mares in corrals. The results of these trials led to the utilization of a standard combination of 5.5 mg of etorphine hydrochloride, 150 mg of xylazine hydrochloride, and 3 mg of atropine sulfate in a 7-ml dart syringe for field capture. This combination was used, administered by dart gun from helicopters, to capture 87 free-ranging feral horses from about 80 bands. Five mares died at the time of capture and the remains of t...
Juzwiak JS, Milton JL.A 4-day-old foal underwent repair of a proximal metaphyseal fracture of the tibia. After closed reduction, fixation was achieved by use of blind cross-pinning. Thirty-five days after surgery, radiography demonstrated complete healing. The foal was mildly lame 4 months after repair of the fracture. Blind cross-pinning may be considered as a method of repair for certain long bone fractures in small foals.
Schumacher J, Bratton GR, Williams JW.The pudendal and caudal rectal nerves in four male and five female adult crossbred horses were anesthetized with a local solution. The injection site was located at the foramen for the caudal gluteal artery and vein in the sacrosciatic ligament. Twenty milliliters of local anesthetic solution were injected via a 15-cm, 18-gauge needle. Quantitative data on anesthesia were determined from these injections. Dye was injected with the anesthetic in four additional horses so that accurate placement of the solution could be determined at postmortem examination. Satisfactory anesthesia of the anus, p...
Watkins JP, Auer JA, Morgan SJ, Gay S.The effect of pulsing electromagnetic field (PEMF) therapy on the healing of surgically created defects in equine superficial digital flexor tendons was evaluated. Defects were created in both front superficial digital flexor tendons of 20 horses. The defect in 1 limb was exposed to a PEMF for 2 hours daily. The other limb served as a control. Histologic and immunofluorescent evaluations were done in horse killed at postsurgical weeks 2, 4, 8, 12, and 24. Therapy with the PEMF significantly (P less than 0.05) delayed the maturation of the tissue formed within the defect at postsurgical weeks 8...
Martens RJ, Malone PS, Brust DM.Oral lactose tolerance tests were evaluated in 25 healthy foals (principals) assigned to 4 groups of approximately 1 week, 4 weeks, 8 weeks, and 12 weeks of age. Lactose monohydrate (1 g/kg of body weight [in a 20% water solution]) was administered via nasogastric tube after a 4-hour fast. Plasma glucose concentrations were monitored before dosing (0 minutes) and sequentially for 300 minutes. Six control foals were given a volume of water equivalent to the volume of lactose monohydrate administered to principal foals. After oral lactose loading, mean plasma glucose concentrations of all princi...
Watkins JP, Auer JA, Gay S, Morgan SJ.Full-thickness defects were surgically created in the superficial digital flexor tendons of the front limbs of 20 horses. Tissues formed within the defect were evaluated histologically, and the collagen composition of the tissue was determined by immunofluorescence. Transformation occurred from loose fibrillar areas of types I and III collagen and pericellular types IV and V collagen to dense bundles of type I collagen fibers. Loose fibrillar areas of types I and III collagen were present after 24 weeks. Histologically, in horses killed after 2 weeks, the tissue within the defect was a randoml...
Takai S, Kawazu S, Tsubaki S.An enzyme-linked immunosorbent assay (ELISA) was used to diagnose Corynebacterium (Rhodococcus) equi infection in foals. In tests done with different antigen-extraction procedures (sodium dodecyl sulfate, sodium deoxycholate, polyoxy-ethylene [9] p-tert-octylphenol, polyoxy-ethylene [9-10] p-tert-octylphenol, sonification, homogenization, and heat treatment at 121 C), Tween 20 was a satisfactory reactive antigen. Using hyperimmune rabbit sera or infected foal sera, we investigated the specificity and the sensitivity of the ELISA with the Tween 20 antigen of the different serotypes or of the is...
Bertone JJ, Dill SG.An ingested metallic foreign body migrated from the stomach and induced restrictive pericarditis in a horse. Necropsy revealed chronic abdominal and acute thoracic lesions. Although rare, ingested foreign body migration should be considered in the differential diagnosis of body cavity disease in horses.
Ruoff WW, Sams RA.The pharmacokinetics and bioavailability of cephalothin given to 6 horse mares at a dosage level of 11 mg/kg of body weight IV or IM were investigated. The disposition of cephalothin given IV was characterized by a rapid disposition phase with a mean half-life of 2.89 minutes and a subsequent slower elimination phase with a mean half-life of only 14.7 minutes. The mean residence time of cephalothin was 10.6 +/- 2.11 minutes. The total plasma clearance of cephalothin averaged 13.6 ml/min/kg and was caused by metabolism and renal elimination. Renal clearance of cephalothin averaged 1.32 ml/min/k...
Rousselle JC, Gillet G, Fillion G.The solubilization of the serotonergic 5HT1 and 5HT3 sites was performed with digitonin and sodium cholate at 1% (final concentration). Two binding sites for [3H]5HT were observed on rat or horse brain synaptosomal membranes solubilized with these detergents. The corresponding dissociation constants (KD) were 1-3 nM and 13-30 nM respectively. These values were closely similar to those corresponding to 5HT1 and 5HT3 sites located in intact membranes. The solubilized sites specifically bound 5HT. The effect of GTP decreasing the binding to 5HT1 sites was lost on solubilized 5HT1 sites; it was re...
Zink MC, Yager JA, Prescott JF, Wilkie BN.Bronchoalveolar lavage was performed 5 times, sequentially, on 3 healthy foals while each foal was 6 to 63 days of age. Phagocytosis and bactericidal assays were performed on recovered alveolar macrophages. Corynebacterium equi and alveolar macrophages at a ratio of 10:1 were incubated for 1 hour in medium containing 1% heat-inactivated rabbit anti-C equi serum. After incubation, greater than 90% of the alveolar macrophages contained at least 1 ingested bacterium and each alveolar macrophage contained 9.4 +/- 1.0 bacteria (mean +/- SE). After alveolar macrophages and C equi were incubated for ...
Prescott JF, Sweeney CR.Combined antimicrobial drug treatment was recommended for foals with Corynebacterium equi pneumonia. The preferred combination is orally administered erythromycin estolate (25 mg/kg of body weight, QID) plus rifampin (10 mg/kg, BID). Erythromycin estolate also can be combined for synergistic effect with sodium benzyl penicillin given IV (100,000 IU/kg, QID) or with ampicillin given IV (11 to 15 mg/kg, QID). A third choice is sodium benzyl penicillin IV with gentamicin IM (2.2 mg/kg, TID) or with kanamycin IM (10 mg/kg, QID). Gentamicin should be combined with penicillin G or ampicillin and not...
van der Velden MA, Schuitemaker EA.The aetiology, clinical symptoms and treatment of equine periodic ophthalmia are discussed. Particular attention is paid to the possible role in aetiology of Onchocerca cervicalis microfilariae. Corticosteroids and atropine are the most important therapeutic drugs.
Blanchard TL, Elmore RG, Kinden DA, Berg JN, Mollett TA, Garcia MC.Fifteen pony mares were assigned to 1 of 3 treatment groups after foaling: Group 1, 35 ml of sterile saline solution was infused into the uterine lumen within 24 hours after parturition (6 mares); group 2, 300 mg of Escherichia coli endotoxin was infused into the uterine lumen within 24 hours after parturition (6 mares); and group 3, 300 mg of E coli endotoxin was infused into the uterine lumen between 72 and 96 hours after parturition (3 mares). Rectal temperatures were taken at -1, -0.5, 0, 0.5, 1, 1.5, 2, 3, 4, and 5 hours after treatment. Venous blood samples were also taken at these times...
Rhodes JB, Schweitzer D, Ogg JE.Non-O1 Vibrio cholerae was isolated from a horse (Equus caballus), a lamb (genus Ovis), and two American buffalo (Bison bison) suffering from enteric disease in the western part of Colorado. In 1981, a foal died of apparent respiratory failure. Necropsy findings included heart failure and gastroenteritis. V. cholerae serovar 347 (Smith) was isolated from the colon of this animal. V. cholerae serovar 27 (Smith) was isolated in 1983 from the intestine of a feedlot lamb suffering from pneumonia and severe watery diarrhea. In 1984, an enteric disease occurred in a herd of American bison. The sick ...
Sweeney CR, Divers TJ, Benson CE.Anaerobic bacteria are important and overlooked bacterial pathogens of the lower respiratory tract in horses. Twenty-one of 46 horses with pleuropneumonia had anaerobic bacteria isolated from pleural fluid or from tracheobronchial aspirate. Bacteroides oralis and B melaninogenicus were the anaerobes most frequently isolated. Survival was significantly less for horses from which anaerobes were isolated than for horses from which anaerobes were not isolated. Putrid odor was associated with the pleural fluid and/or breath in 62% of the horses from which anaerobes were isolated. In these horses, t...
Srivastava SK, Barnum DA.The ability of either formalin-treated or heat-inactivated whole Streptococcus equi cell vaccines or partially purified M-protein of S. equi to give rise to protective antibody levels was studied in Standardbred foals by serological means. Two commercial preparations, i.e. a beta-propiolactone killed whole S. equi cell bacterin and a cell-free extract of S. equi cells were included in the study. The mean passive hemagglutination antibody titers (10 X log2) in sera of foals given either four doses of formalin-treated whole cell vaccine or an initial dose of formalin-treated followed by three do...
Ensink JM, Barneveld A, Klein WR, van Miert AS, Vulto AG.The plasma disposition of ampicillin after intravenous administration at a dose rate of 15 mg/kg was studied in six healthy, 1-month-old foals. The oral bioavailability of pivampicillin was determined in the same foals at four ages, ranging from 11 days to 4 months. Pivampicillin was administered orally at a dose rate of 19.9 mg/kg, which is equivalent on a molecular basis to 15 mg/kg ampicillin. Ampicillin concentrations in plasma were determined up to 12 hours after administration. After intravenous administration, the mean distribution and elimination half-lives of ampicillin were 0.121 and...
Dupont S, De Spiegeleer A, Liu DJ, Lefère L, van Doorn DA, Hesta M.Commercial immunoglobulin E (IgE)-based tests are available for diagnosis of food allergies and are commonly used in equine practice. However, these tests have been proven unreliable as a screening method in man and other species, but not critically evaluated in equids. Therefore, a commercially available IgE-based test for horses was evaluated. Objective: To evaluate the consistency of the results obtained with a commercially available IgE-based test for food allergy diagnosis in ponies (Phase I) and to subject ponies to a provocation trial with the presumed allergens (Phase II). Methods: All...
Loch W, Worthy K, Ireland F.Sixteen non-pregnant pony mares were divided into four groups of similar age and bodyweight (bwt). Groups were randomly assigned to one of four treatments consisting of oral administration of perphenazine (0.5 and 1.0 mg/kg bwt, phenothiazine (10 mg/kg bwt) and a control group. Blood samples were taken by jugular venepuncture and plasma prolactin concentrations measured using an homologous assay for equine prolactin. Analysis of variance was conducted on data designed as a split plot over time. Perphenazine given orally (0.5 and 1.0 mg/kg bwt) increased plasma prolactin concentrations when mea...
Golland LC, Evans DL, McGowan CM, Hodgson DR, Rose RJ.Red blood cell hypervolaemia has been used for diagnosis of overtraining in racehorses, and has been suggested as a mechanism of this cause of loss of racing performance. The effects of overload training (OLT) on the plasma, blood and red cell volumes were investigated in a prospective study in 12 Standardbred horses. Measurements of blood volumes were made after eight and 32 weeks of an exercise training study. Horses were randomly allocated to OLT and control groups (n=6) after 16 weeks of training. Training duration and intensity were increased more rapidly for the OLT group from week 16, u...
al-Afaleq AI, Abu Elzein EM, Hassanein MM.The present epidemiological status of African horse sickness in Saudi Arabia, as shown by seroconversion, virus isolation and clinical observation of sentinel horses is described. No African horse sickness virus activity was detected throughout the duration of the study (from November 1992 to March 1995). These findings support previous reports that African horse sickness is not endemic in Saudi Arabia.
Monzón CM.A direct agglutination test is described to diagnose 'Mal de Caderas' caused by Trypanosoma evansi. The antigen used was a suspension of trypsin-treated parasites stabilized with formalin. The test was evaluated in horses with both natural and experimental infections. Test sensitivity and specificity were 94 and 97%, respectively. Treatment of serum with 2-mercaptoethanol before testing permitted the differentiation of IgM and IgG antibodies, and possible differentiation of current infection from past exposure to the parasite. The antigen was stable over a 6-month evaluation period and also sh...
Bidwell LA.Equine anesthesia is complicated regardless of the procedure being performed. Anesthesia for the mare experiencing dystocia is complicated by the size of the fetus, positioning of the mare for the procedure, and concern over drug effect on the fetus through the neonatal period. Anesthesia of the neonate is complicated by multiple factors, specifically, sensitivity to the drugs administered. Ventilatory support, minimizing drugs administered, and minimizing anesthesia time are essential for a positive outcome.
Palmisano M, Bender S, Johnson AL.We describe the unique clinical presentation of a central nervous system neoplasm in a 6-month-old draft horse cross gelding. Based on the neurologic examination at admission, neurolocalization was most consistent with a mildly asymmetric cervical, multifocal, or diffuse myelopathy. Mild vestibular involvement also was considered, but no cranial nerve deficits were observed. The gelding was negative for Sarcocystis neurona or Neospora hughesi based on paired serum and cerebrospinal fluid (CSF) samples analyzed, with no evidence of cervical compression based on contrast myelography. The horse w...
Charman RE, Vasey JR.Chronic facial defects extending into the sinuses of two mares were repaired using periosteal flaps. Partial osseous bridging was established over the defects following repair. Previous attempts to close the defects with skin alone had failed. A periosteal flap is a simple surgical technique that provides the foundations for successful repair, despite the chronicity of some fistulae.
Giordano A, Castagnetti C, Panzani S, Paltrinieri S, Freccero F, Veronesi MC.In newborn babies, endothelin 1 (ET-1), a potent vasoconstrictor, increases during septicemia and severe respiratory syndromes. Because equine neonatal sepsis (ENS) and perinatal asphyxia syndrome (PAS) are major causes of morbidity and mortality in newborn foals and because no information on the concentration of ET-1 in healthy and sick foals has been reported yet, the aims of this study were (1) to define the serum concentration of Big ET-1 in healthy neonatal foals during the first week of age; (2) to preliminarily explore the diagnostic and prognostic role of Big ET-1 during ENS and PAS. S...