Equine health encompasses the study and management of diseases, disorders, and overall well-being of horses. It involves understanding various physiological systems, preventive care, and treatment strategies to maintain optimal health in equine populations. Common areas of focus include nutrition, infectious diseases, orthopedic conditions, and reproductive health. Research in equine health aims to advance knowledge on diagnostic methods, therapeutic interventions, and management practices that improve horse welfare and performance. This page collects peer-reviewed research studies and scholarly articles that explore the diverse aspects of equine health, offering insights into current findings and advancements in the field.
Hamilton MJ, Hughes IM, Hegreberg GA.Serum testosterone levels were measured in normal young male horses (29 to 34 weeks old). No differences were found between gelded and intact males. The values for all the horses were low. On the basis of their testosterone levels, all the horses were prepubertal.
Coignoul FL, Bertram TA, Cheville NF.Neutrophils isolated from venous blood of adult and foal ponies inoculated with equine herpesvirus-1 were evaluated by in vitro function tests and by electron microscopy. Foals had fever and severe neutropenia 24 hours after inoculation; increased neutrophil random migration under agarose and decreased antibody-dependent cell-mediated cytotoxicity were significant at 24 hours, but values had returned to preinoculation levels by 72 hours. Mares had fever and leukopenia of less severity, increases in neutrophil migration, and longer persistence of primary granule release than were seen in foals....
Slocombe JO, McCraw BM.The efficacy of ivermectin against later fourth-stage Strongylus vulgaris larvae was studied in pony foals at 14 and 35 days after treatment. These foals had been reared parasite-free, inoculated with 500 infective larvae and 56 days later given either ivermectin at 200 micrograms/kg or a placebo intramuscularly. At necropsy, foals were examined for lesions and larvae grossly and histologically. Ivermectin was found to be highly effective (98.6%) against later fourth-stage larvae in five foals which were examined at 35 days after treatment, but not in five others examined at 14 days (72.5%). I...
Blythe LL, Watrous BJ, Schmitz JA, Kaneps AJ.Acute onset of vestibulocochlear and facial nerve dysfunction due to a stress fracture of the petrous part of the temporal bone was diagnosed in 3 horses. The fracture was secondary to chronic inflammatory changes in the petrous part of the temporal bone and the proximal stylohyoid bone, with fusion of the temporohyoid joint. Bacterial meningoencephalitis was a complicating factor. Treatment resulted in reduction of severity of clinical signs in 2 of the 3 cases, but residual compensated vestibular deficits persisted.
Blue MG, Hannwacker MA.Persistent purulent endometritis in a mare was attributed to an unclassified species of Corynebacterium. Following intrauterine infusions of 20% betadine for 5 days the purulent vulval discharge ceased and the mare appeared clinically normal. Based on histological examination of endometrial biopsy samples, the severe acute inflammatory reaction had largely resolved 2 days after therapy. Three maiden mares considered resistant to bacterial endometritis received single intrauterine inoculations of 1.8 X 10(9) colony-forming units of the Corynebacterium species. The uterine response was followed ...
Bristol DG, Fubini SL.Lipomas involving the musculoskeletal system were seen in 3 horses. The lipomas were on the thorax of 2 horses and the stifle of the third horse. The thoracic lipomas were surgically removed. No recurrence has been noted by 8 months in either case. The lipoma on the stifle had invaded the surrounding tissue and the horse was euthanatized. Unlike mesenteric lipomas, which occur in older horses, these lipomas all occurred in horses less than 2 years of age.
Sweeney RW, Sweeney CR.Horner's syndrome developed in 2 horses after routine jugular venipuncture. Signs included unilateral sweating of the face in both horses and ptosis in 1 horse. The signs resolved within 14 hours. Signs of a perivascular injection did not develop in either horse. Although Horner's syndrome has been reported after perivascular jugular injections these cases illustrate that the syndrome may develop following routine intravenous injections.
Todhunter RJ, Stick JA, Trotter GW, Boles C.Esophageal strictures developed in 7 horses that were treated for esophageal obstruction. A soft diet was fed to all horses, with intermittent nasogastric tube feeding in one, and medication included nonsteroidal anti-inflammatory drugs. Maximal reduction in esophageal lumen diameter was evident by 30 days following circumferential esophageal ulceration, after which lumen diameter increased rapidly. Five horses were clinically normal by 60 days after the esophageal injury. Two horses were euthanatized at the owner's request, 16 and 17 days after the original insult.
Ellenberger MA, Kaeberle ML, Roth JA.A procedure was developed for isolating large numbers of purified polymorphonuclear leukocytes (PMNs) from the peripheral blood of horses. Equine PMN function was evaluated by three procedures: 1) Staphylococcus aureus ingestion, 2) nitroblue tetrazolium reduction, and 3) iodination. Four preparations of R. equi were added to polymorphonuclear leukocytes (PMNs) in each test system. Live bacteria, heat-killed bacteria, the washed pellet from heat-killed bacteria, and the supernatant fluid from heat-killed bacteria were evaluated for effects on equine PMN function. None of the R. equi preparatio...
Fitzpatrick DR, Studdert MJ.The specificity of selected immune responses to equine herpesvirus type 1 (EHV-1) and type 4 (EHV-4) was examined in 3 colostrum-deprived specific-pathogen-free foals. Single foals were vaccinated with inactivated EHV-1, inactivated EHV-4, or control cell lysate plus adjuvant followed by successive intranasal challenge exposures with EHV-1 and EHV-4 or with EHV-4 and EHV-1. Vaccination with inactivated virus preparations elicited cellular immune responses and antibody which were augmented by subsequent challenge exposures. Cellular immune responses, as measured by in vitro lymphocyte blastogen...
O'Niell FD, Issel CJ.Growth kinetics of equine influenza virus-A1, equine herpesvirus-1, and equine rhinovirus-1 were determined in susceptible cell monolayers and in organ cultures of equine fetal tracheal and nasal turbinate epithelium. Equine influenza virus-A1 was replicated in cell and organ cultures and was released more readily and for longer periods from nasal turbinate epithelium than from tracheal epithelium. Equine herpesvirus-1 was also replicated in cell and organ cultures. During the first 24 hours after inoculation, equine herpesvirus-1 was released more readily from tracheal epithelium than from na...
Scott DW, Walton DK, Smith CA, Lewis RM.Indirect immunofluorescence testing for pemphigus-like antibodies was performed on 79 horses: 28 horses with various nonpemphigus dermatologic diseases, 21 horses with various nondermatologic diseases, and 30 normal horses. Pemphigus-like antibodies were detected in 6 horses: 3 normal horses with titers of 1:40, 2 horses with dermatophilosis at titers of 1:10 and 1:80, and 1 horse with lymphosarcoma at a titer of 1:320. It was concluded that equine pemphigus-like antibodies are a potential source of misinterpretation and misdiagnosis in indirect immunofluorescence testing. Direct immunofluores...
Prescott JF, Coshan-Gauthier R, Barksdale L.Antibody to equi factor(s) in cases of Corynebacterium equi pneumonia in foals was detected using C. pseudotuberculosis exotoxin sensitized calf red blood cells. The test was standardized using antitoxin produced in rabbits by injection of equi factor(s). All sera from ten foals with culture-diagnosed C. equi pneumonia had antibodies to equi factor(s) (titre range 8-256, mean 74.0) and nine sera from 11 foals with suspected C. equi pneumonia also showed antibodies (titre range 4-512, mean 136.4). Two of five pneumonia foals with transtracheal aspirate cultures not yielding C. equi had such ant...
Skarda RT, Muir WW, Ibrahim AI.The venous plasma concentrations of mepivacaine were determined in 7 adult mares (420 +/- 17.1 kg) given an injection of a 2% solution of the hydrochloride at either the sacral (S2-3 to S5-C1) epidural space or the midsacral (S2-3) subarachnoid space. An average dose of 91.4 +/- 15.7 mg (4.6 +/- 0.8 ml) was needed to produce caudal epidural analgesia (CEA) and 26.7 +/- 5.4 mg (1.3 +/- 0.3 ml) to produce caudal subarachnoid analgesia (CSA). Maximal caudal analgesia extended from spinal cord segments S-1 to coccyx during CEA and CSA. The onset of analgesia as measured by response to superficial ...
Richardson DW.Fifteen longitudinal fractures involving the medial condyle of the third metatarsal bone were diagnosed in racing Thoroughbreds and Standardbreds. Twelve were repaired surgically with lag screws placed through stab incisions. Two of the horses suffered catastrophic fracture of the third metatarsal bone during recovery from anesthesia, and 3 more sustained complete fractures within 4 days of the repair. Of 3 horses with fractures treated without surgery, 2 healed without complication. Preoperative radiography did not demonstrate a nonlongitudinal fracture component in any of the horses that sus...
Papkoff H, Murthy HM, Roser JF.The tyrosine residues of equine chorionic gonadotropin have been nitrated with tetranitromethane and the resulting effects on the biological and immunological activities of the hormone studied. All of the tyrosine residues in equine chorionic gonadotropin were found to react with tetranitromethane when a 100-fold molar excess of reagent was used or with an 8.6 molar excess in the presence of 5 M guanidine hydrochloride. Complete nitration abolished the biological activities and decreased the immunological activity of the hormone. The nitration of one tyrosine residue resulted in the loss of 70...
Knight AP, Kimberling CV, Stermitz FR, Roby MR.The death of 10 horses was attributed to feeding dried grass hay containing hound's-tongue, Cynoglossum officinale. Affected horses developed weight loss, icterus, photosensitization, and hepatic encephalopathy. Histologic examination of the liver of 3 of the horses revealed megalocytosis, biliary hyperplasia, and fibrosis characteristic of pyrrolizidine alkaloid poisoning. Hound's-tongue was found to contain large quantities (0.6% to 2.1%, dry matter basis) of toxic pyrrolizidine alkaloids, which, when fed to a pony for 20 days, caused liver fibrosis and biliary hyperplasia.
Edwards GT.Sarcocystis was detected in oesophageal samples from 245 (62 per cent) of 394 horses and ponies killed at a Cheshire abattoir between February and August 1981. Prevalence of infection was closely related to age, increasing from 28.6 per cent of animals up to two years old to 88.9 per cent of those over eight years old. There were no significant regional differences in prevalence between horses from north west England, Yorkshire or South Wales. Significantly more female horses were infected (69.7 per cent) compared with males (56.2 per cent). Gross examination methods detected fewer than 55 per...
van Leeuwen W.A number of findings on twin pregnancies in mares recently reported in the literature are evaluated in the present paper. From these findings it emerges that twin pregnancies in mares very rarely develop from a synchronous (less than 2 days apart) double ovulation but rather from an asynchronous (much greater than 2 days apart) double ovulation. The significance of these findings in daily practice is pointed out. Moreover, it was found that in more than 50 per cent of the cases in which twin pregnancies had been diagnosed about day 20, one embryo had died by day 36. From this fact it is conclu...
Mason DK, Collins EA, Watkins KL.An investigation into the incidence of exercise induced pulmonary haemorrhage (EIPH) in thoroughbreds in Hong Kong was carried out between the 1981 and 1983 racing seasons. A total of 1039 post race endoscopic examinations were performed in 1982-1983 and the results indicated that 46.8 per cent of runners had EIPH. This was not statistically different from the percentage of horses showing EIPH during 1981-82 (46.9 per cent). As it had been postulated that dust, especially from straw, could be implicated in lung haemorrhage a proportion of horses were bedded on paper in the 1982-83 season. No s...
Junge RE, Sundberg JP, Lancaster WD.In a retrospective study encompassing 13 years of diagnostic work, papillomas and squamous cell carcinomas from horses were screened for papilloma-virus antigens, using the peroxidase-antiperoxidase technique. Papillomas were most commonly found on the penis and vulva, followed by cutaneous, ocular, and oral locations. Squamous cell carcinomas were most frequently located on the third eyelid and cornea, followed by genital, oral, maxillary sinus, and cutaneous sites. Papillomavirus structural antigens were detected in 7 cutaneous and 5 genital papillomas, but not in squamous cell carcinomas.
White RA, Gerring EL, Jackson PG, Noakes DE.Persistent bleeding from the vulva was the only presenting clinical sign in five non-pregnant pluriparous mares varying in age from eight to 20 years. These were two hunter types, one shire, one thoroughbred and one Arab pony. The haemorrhage originated from ulcerated varicose veins present on the dorsal wall of the vagina adjacent to the vestibulovaginal junction. All five mares were successfully treated, by submucosal resection (two), ligation of vessels (two) or diathermy (one). In four mares there was evidence of vulval incompetence caused by depression of the perineum. The importance of t...
Gleed RD, Dobson A, Hackett RP.In the quietly standing horse the bronchial arterial blood flow is low, 0.1-0.2% of the pulmonary arterial flow. In horses anaesthetized with halothane, the bronchial arterial flow is reduced by a greater fraction than that in the pulmonary artery. Thus the shunting through the bronchial circulation is decreased about 3-fold by anaesthesia, and cannot, therefore, contribute significantly to the increased alveolar-arterial gradient seen in dorsal recumbency. The results indicate bronchial vasoconstriction under anaesthesia.
Raidal SL, Wright JD.Records of 220 thoroughbred horses presented to the Randwick Equine Centre or the University of Queensland Veterinary Teaching Hospital for surgical management of carpal injury were reviewed. Details of racing performance were obtained, enabling evaluation of racing success following surgery. Age and sex matched control horses not known to have suffered carpal injury were selected from the Australian Stud Book and the Australian Racehorse Register. Control and treated populations were compared in terms of overall career racing success. Radiographs or xeroradiographs from 198 horses were availa...
Al-Bagdadi FK, Eilts BE, Richardson GF.Scanning electron microscopy (SEM) was used to study the endometrium of nine 1-year-old thoroughbred mares after twice intrauterine infusions of gentamicin, on 2 consecutive days. Five mares were infused on 2 consecutive days with 40 ml gentamicin (50 mg/ml) mixed with 80 ml of normal saline. Four mares served as controls and were infused with 120 ml of saline on 2 consecutive days. Endometrial biopsies were obtained from all mares 3 days after the second intrauterine infusion. Each biopsy was processed for SEM by standard methods. The endometrial epithelium of the gentamicin-infused mares had...
Sinn D, Wintzer HJ.The pharmacokinetics of racemic phenprocoumon were studied in 8 adult horses after the single intravenous and oral administration of 0.75 mg/kg. After i.v. administration the plasma concentration of phenprocoumon showed a biphasic decline in time. The pharmacokinetics were calculated on the two-compartment open model. The average plasma half-life (beta-phase) was 22 hours, the apparent volume of distribution was 0.61 l/kg, Cltot was 25.2 ml/kg/h (13.9-40.9 ml/kg/h). The systemic bioavailability of oral phenprocoumon was 97.6%, Tmax was found to be 4-12 hours. The effect of phenprocoumon on the...
Hagedorn HW, Schulz R.Statistical analysis of normally occurring cortisol levels in serum and urine of horses served to recommend thresholds for this corticosteroid in these body fluids, as application of exogenous cortisol as well as ACTH may elevate the cortisol concentrations above the proposed threshold. The present study contributes to the general issue of how to establish thresholds for trotting horses upon sportive examination. 100 randomly selected post competition serum and urine samples, respectively, were submitted to cortisol analysis by means of HPLC. Concentrations of the endogenous corticosteroid in ...
Stewart SG, Johnston JK, Parente EJ.An 8-year-old multiparous Thoroughbred broodmare was admitted for evaluation of a rectal tear sustained during parturition. Results: On initial evaluation, the mare had mild signs of abdominal discomfort. A full-thickness rectal tear located 30 cm cranial to the anus and extending approximately 15 cm longitudinally along the surface of the small colon between the 4 and 6 o'clock positions, when viewed from behind, was diagnosed on examination per rectum. Results: Laparoscopic evaluation of the abdomen was performed to assess the tear and extent of peritoneal contamination. A hand-assisted repa...
Johnson BJ.Immediately record the findings. A tape recorder would be excellent for this. If none is available, findings should be written down as soon as possible before memory of the examination fades. It is important to record comments on every organ that you examined. Three years from now in a court deposition, it may be difficult for the practitioner to remember if he looked at the adrenal glands or if there was no gross evidence of hyperplasia. When writing a report, it is a good idea to describe the tissue changes rather than just to give an interpretation. An example of the latter would be, "The h...
Kang H, Sole-Guitart A, Mellor VA, Gaughan JB, Zsoldos RR.Continuous accurate attainment of the body temperature of foals is important to detect early stages of severe heat stress or fever due to a systemic illness. Among a number of methods to measure body temperature, measuring rectal temperature with a digital thermometer is most frequently used due to being relatively fast and simple method. It is also comparatively accurate and correlates well with the core body temperature. However, this method requires restraining the foal for a few seconds to obtain the temperature, and it can be dangerous for the handling person. Percutaneous thermal sensing...
Ralston SL, Molnar A.In 1999, the Young Horse Teaching and Research Program (YHTRP) was initiated at Rutgers University. The unique aspect of the program was using horses generally considered "at risk" and in need of rescue, but of relatively low value. The risks of using horses from pregnant mare urine (PMU) ranches and Bureau of Land Management (BLM) mustangs were high, but, ultimately, unrealized. No students or staff members were seriously injured over the course of the next 12 yr, and the horses were sold annually as highly desirable potential athletes or pleasure horses, usually at a profit. The use of "at r...
Gerdemann R, Deegen E, Kietzmann M, Venner M.In the present study the significance of eicosanoids in the development of shock in horses on the basis of ileus has been investigated using the prostanoids thromboxane B2 (TXB2) and prostaglandine E2 (PGE2) as indicators. The prostanoid synthesis inhibitor flunixin meglumine was to be examined regarding its efficacy in the effective blockade of the synthesis of these mediators within the peri-operative timeframe as well as its effects on clinical signs and laboratory parameters. 21 horses suffering from ileus and ready for surgical intervention received an intravenous flunixin dosis of 1.1 mg...
Seeherman HJ.The use of motorized treadmills has made it possible to evaluate equine poor performance with sophisticated diagnostic techniques during peak exercise. Treadmill exercise tests currently being used for clinical evaluations include treadmill gait analysis, dynamic hoof balancing, endoscopic evaluation of upper airway function, and exercise performance profiling. Large motorized treadmills (1 to 1.5 m in width and 4 to 5 m in length) are best suited for clinical evaluations. Ideally, the treadmill should be installed in-ground using a pit. This type of installation results in the tread surface b...
Casteleyn C, Cornillie P, Tüllmann V, Van Cruchten S, Van Ginneken C.An Oldenburg colt with wry nose was autopsied after having lived for only 30 min. It presented cyanotic oral mucosae, underdeveloped eyes and a right-sided temporal osseous mass. The applicable nomenclature for the defects is discussed, and the potential etiopathogenesis is explored by describing the normal embryonic development of the affected body parts.
Easley KJ.Infertility in the mare associated with VVR must be managed as a complex problem. A complete reproductive evaluation of the mare is required to establish the cause of VVR in order for proper therapy to be recommended. Establishing a prognosis for the mare's future breeding soundness is important to the horse owner and breeding manager. VVR is almost always associated with other reproductive problems and must be dealt with in view of this.
Watson ED, Dixon CE.The distribution of T lymphocytes and of cells bearing MHC Class II antigens in the endometrium of the mare was studied using an avidin-biotin-peroxidase staining method. The cells within the endometrium which expressed MHC Class II were macrophages, lymphocytes, monocytes, dendritic cells, epithelial cells and endothelial cells. MHC Class II expression increased significantly (P < 0.05) in the luminal epithelium and tended (P = 0.0573) to increase in the subepithelial layers during oestrus. Numbers of T lymphocytes did not differ between oestrus and dioestrus. MHC Class II expression and T...
Baird AN, Scruggs DW, Watkins JP, Taylor TS.Sixteen horses were allotted to 4 groups of 4 horses each to evaluate the effect of tendon sheath lavage with 4 solutions (balanced electrolyte solution, 0.1% povidone-iodine, 0.5% povidone-iodine, and 0.5% chlorhexidine). The synovitis caused by 0.1% povidone-iodine lavage was not appreciably worse than that caused by balanced electrolyte solution lavage, but the 0.5% povidone-iodine and chlorhexidine lavages caused severe synovitis, and, therefore, should not be used for tendon sheath lavage.
Sullivan KE, Snyder JR, Madigan JE, Pascoe JR, Farver TB, Thurmond MC, Andresen JW.Granulocyte colony-stimulating factor (G-CSF) is a glycoprotein that regulates the proliferation and maturation of hematopoietic progenitor cells and modulates the function of mature neutrophils. The responses to administration of G-CSF alone, and in combination with antimicrobials, were studied in an equine model of ascending colon ischemia. Complete segmental colonic ischemia (3.75 hours) with pelvic flexure enterotomy was created in four treatment groups. Group 1 horses received recombinant canine G-CSF (10 micrograms/kg, every 24 hours, intramuscularly), gentamicin sulfate (2.2 mg/kg, ever...
Tudor RA, Bowman KF, Redding WR, Tomlinson JE.A 9-year-old gelding was evaluated because of a 30-day history of mild intermittent left forelimb lameness. The only detectable abnormality was mild atrophy of the musculature of the proximal portion of the left forelimb. The cause of the lameness could not be determined. The horse was discharged from the hospital, but was reexamined 6 weeks later because of worsening of the lameness. At that time, the horse resisted flexion and extension of the left shoulder joint, and results of evaluation of an ultrasound-guided aspirate of fluid from the intertubercular bursa were suggestive of infection. ...
Simmons HA, Cox JE, Edwards GB, Neal PA, Urquhart KA.This paper reports seven cases of penile paraphimosis which occurred in both entire and castrated horses in association with general debility. Two cases were discharged after treatment while still suffering from partial paralysis; one was discharged at the owner's request with complete paralysis; three were destroyed and one died during treatment. Identified causes of debility were malnutrition, severe parasitism, glucose malabsorption and salmonellosis.