Veterinary medicine for horses encompasses the study and application of medical practices to diagnose, treat, and prevent diseases in equine species. This field involves a comprehensive understanding of equine anatomy, physiology, pathology, and pharmacology. Veterinary practitioners employ a range of diagnostic tools and therapeutic interventions to address health issues in horses, including lameness, gastrointestinal disorders, respiratory conditions, and infectious diseases. Preventative care, such as vaccination and deworming programs, is also a significant aspect of equine veterinary medicine. This page gathers peer-reviewed research studies and scholarly articles that explore various aspects of veterinary medicine as it pertains to horses, including advancements in diagnostic techniques, treatment protocols, and preventive health strategies.
Provost PJ, Ortenburger AI, Caron JP.Horses experience a number of ophthalmic diseases and injuries that may result in loss of function of the eye. In the treatment of end-stage ophthalmic disease or injury that precludes salvage of the eye, the use of an inert, silicone prosthetic implant is a cosmetic alternative to simple enucleation. Eleven horses treated either by enucleation and insertion of an intraorbital prosthesis (n = 9) or by evisceration and insertion of an intraocular prosthesis (n = 2) were evaluated for postoperative complications and for long-term cosmetic results. Of the 11 horses treated, complication rate was ...
Wilson DG, Mays MB, Colahan PT.Seven horses with canker had radical surgical debridement and various irritant substances applied to the wounds. Four of the horses were clinically normal in (mean) 3.6 months, 1 mare was lame, and 2 horses were euthanatized because of complications of their treatments. Seven horses that had minor surgical debridement and antimicrobial agents used systemically and topically were clinically normal in (mean) 1.4 months. Seemingly, canker in horses should be managed using minor surgical debridement and appropriate antimicrobial therapy.
Clabough DL, Conboy HS, Roberts MC.Using radial immunodiffusion as a standard, 4 screening techniques for detection of failure of passive transfer in equine neonates were compared for sensitivity, specificity, positive and negative predictive values, efficiency, and cost. The techniques compared were latex agglutination test, membrane filter ELISA, dipstick ELISA, and glutaraldehyde coagulation (GC) test. Test results of 50 serum samples from foals 24 to 60 hours old revealed consistently highest accuracy in the GC test at IgG concentrations of 400 and 800 mg/dl, and lowest cost per test, using the GC test. Two hundred fifty-th...
Barr AR, Sridhar B, Denny HR.Five horses with long incomplete longitudinal fractures of the third metacarpal bone and three horses with similar fractures of the third metatarsal bone were examined. In three of the metacarpal fractures a long incomplete fissure extended proximomedially, in association with the more common lateral condylar fracture of the third metacarpal bone, and in the other two cases the fracture originated from the medial aspect of the distal articular surface. In the three horses with fractures of the third metatarsal bone the fractures had a consistent spiral configuration.
Carpenter S, Chesebro B.Similar to other human and animal lentiviruses, equine infectious anemia virus (EIAV) is detectable in vivo in cells of the monocyte-macrophage lineage. Owing to their short-lived nature, horse peripheral blood macrophage cultures (HMC) are rarely used for in vitro propagation of EIAV, and equine dermal (ED) or kidney cell cultures, which can be repeatedly passed in vitro, are used in most studies. However, wild-type isolates of EIAV will not grow in these cell types without extensive adaptation, a process which may attenuate viral virulence. To better define the effect of host cell tropism on...
Lyons ET, Drudge JH, Tolliver SC.Thirteen critical tests (n = 11 horses and 2 ponies) and 4 controlled tests (n = 4 donkeys and 6 horses) were performed to evaluate the activity of the experimental macrocyclic lactone compound F28249-alpha against internal parasites of equids. In the critical tests, activity was determined mainly against the large parasites, but 1 critical test also included benzimidazole-resistant small strongyles. In the controlled tests, evaluation of drug activity included large parasites and stomach worms in all 4 tests, and lungworms in 2 tests. The period between treatment and euthanasia was 6 to 9 day...
Jochle W, Moore JN, Brown J, Baker GJ, Lowe JE, Fubini S, Reeves MJ, Watkins JP, White NA.Detomidine hydrochloride, butorphanol tartrate, flunixin meglumine and xylazine hydrochloride were evaluated in a blind multi-centre clinical trial in 152 horses with abdominal pain. The drugs were administered as follows: detomidine 20 or 40 micrograms/kg bodyweight (bwt); butorphanol 0.1 mg/kg bwt; flunixin meglumine 1.0 mg/kg bwt; xylazine hydrochloride 0.5 mg/kg bwt. Each centre compared responses to the two doses of detomidine with those to one of the other analgesics. The drugs were administered intravenously (i.v.) after clinical assessment of the degree of sweating, kicking, pawing, he...
Stahlbaum CC, Houpt KA.The role of the Flehmen response in equine behavior was investigated under field and laboratory conditions. In Experiment 1, a field study made of five stallions on pasture with between three and eighteen mares each during the season indicated the following: 1) The Flehmen response was most frequently preceded by nasal, rather than oral, investigation of substances; 2) The stallions' rate of Flehmen varied with the estrous cycles of the mares; 3) The rate of Flehmen response did not show a variation with time of day; and 4) The Flehmen response was most frequently followed by marking behaviors...
King JN, Gerring EL.Characteristic motility patterns were seen throughout the gastrointestinal tract in a pony prepared chronically with electromechanical recording devices after developing a simple obstruction of the small intestine. Gross distension of the stomach with fluid produced loss of gastric contractile activity and a chaotic electrogram. These changes were reversed instantaneously when the stomach was decompressed. In the jejunum, proximal to the obstruction, the unique 'colic motor complex' was observed with contractions of longer duration arranged in characteristic pulses of activity. The left dorsal...
Morris DD, Moore JN.Serum immunoglobulin (Ig) titres to core lipopolysaccharide (LPS) were determined in 102 horses admitted to a university referral hospital during a 12-month period for evaluation of colic. Serum samples were collected again 10-14 days later from 84 of the horses. Titres to core LPS were quantitated by an indirect enzyme-linked immunosorbent assay (ELISA), utilising the J-5 mutant of Escherichia coli 0111:B4 as the solid-phase antigen. All horses had natural antibodies to core LPS at the time of admission and the titre was not affected significantly by age, sex or type of gastrointestinal disor...
Bertone AL, Cockerell GL, Lee RE, Stashak TS.Light microscopy, morphometry and scanning electron microscopy (SEM) were used to examine the mucosal morphology of seven intestinal specimens (three from the small intestine and four from the large intestine) from two horses not subjected to surgery and three horses one year after sham-operation for colon resection. Qualitative and quantitative evaluation revealed similar morphology for all horses except that the unoperated horses had significantly (P < 0.05) fewer goblet cells in the crypts of the large intestine. In the small intestine, SEM demonstrated that villus shape varied and range...
Goetz TE, Manohar M, Nganwa D, Gustafson R.The effects of 1.1, 1.5 and 1.8 MAC (minimum alveolar concentration) isoflurane-02 anaesthesia on skeletal muscle blood flow, 02 delivery and vascular resistance were studied in the non-dependent region of seven healthy normothermic, isocapnoeic ponies. Muscle blood flow was determined with 15 microns diameter radionuclide labelled microspheres that were injected into the left ventricle. Muscle blood flow during anaesthesia was compared to unanaesthetised (control) measurements. Isoflurane administration caused a dose dependent decrease in mean aortic pressure, and skeletal muscle (temporalis,...
Murray MJ, Grodinsky C.The pH of the gastric mucosal surface and gastric content was measured in 18 foals (mean age: 20 days) and 27 horses (mean age: 2.9 years) with a pH electrode passed through an endoscope biopsy channel. A reference electrode was attached to a shaved area on the neck. pH Measurements of the gastric mucosal surface at the dorsal squamous fundus (SF), squamous mucosa adjacent to the margo plicatus (MP), glandular fundus (GF) and the fluid or feed contents of the stomach were recorded in duplicate for each animal. In adult horses, the SF pH was greatest (5.46 +/- 1.82), with a decreasing pH ventra...
Merritt AM, Campbell-Thompson ML, Lowrey S.Six healthy six to eight-month-old horses were surgically prepared with Ag bipolar electrodes sutured to the gastric antrum and duodenum. Leads from the electrodes were exteriorised through a stab incision in the flank. During experimental sessions the horses were lightly restrained in stocks and electrode leads were connected to a physiograph to record antroduodenal myoelectrical activity. Intravenous (i.v.) injection of 0.05 mg/kg bodyweight (bwt) of the opioid agonist/antagonist, butorphanol was followed within 2 to 3 mins by a normal appearing period of repetitive spike activity, or phase ...
Baird AN, Taylor TS, Watkins JP.Grade 3 rectal tears were created in 14 horses. Epidural anaesthesia was maintained in all horses for 8 h post injury. In seven horses with cotton filled stockinette packing the rectum, neither gross faecal contamination nor progression of the rectal tear occurred. Seven horses without rectal packing developed faecal contamination of the rectal tear with formation of a faeces filled serosal or mesorectal diverticulum.
LeBlanc MM, Asbury AC, Lyle SK.Uterine response to inoculation with Streptococcus zooepidemicus organisms, 51Cr-labeled 15-microns microspheres, and charcoal was evaluated in 9 mares (4 resistant and 5 susceptible to endometritis) to determine mechanical and cellular clearance rates during the early postovulatory period. Mares were inoculated at estrus prior to ovulation during estrous cycles 1, 3, and 5. Uterine swab specimens for aerobic and anaerobic bacteriologic culture and serum for progesterone determination were obtained on postovulation day 3 during estrous cycle 1, on the day of ovulation during estrous cycle 3, a...
Morris DD, Moore JN.The formation of eicosanoids may be a primary route through which platelet activating factor (PAF) exerts its effects during endotoxemia. Since endotoxemia is a common cause of death in horses, a study was conducted to determine whether PAF could stimulate equine macrophage release of thromboxane A2 (TxA2) and prostacyclin (PGI2) and whether a PAF-receptor antagonist would alter macrophage eicosanoid synthesis. Equine peritoneal macrophages were cultured from clinically normal horses and exposed to various concentrations of PAF, the PAF-receptor antagonist SRI 63-441, endotoxin, or a combinati...
Clark ES, Moore JN.The effects of slow intravenous (i.v.) infusion of a very low dosage of endotoxin (a cumulative dosage of 0.03 microgram/kg bodyweight [bwt] infused over 60 mins) were evaluated in six conscious healthy horses. Duodenal, right ventral colon, and caecal contractions were detected with strain gauge force transducers. Lateral caecal arterial blood flow was measured using transit time ultrasonic blood flow probes. Duodenal contractile activity was not significantly altered by infusion of endotoxin. In contrast, the contractile activity of the right ventral colon 90 and 270 mins after infusion of e...
Cook RF, Gann SJ, Mumford JA.An enzyme-linked immunosorbent assay (ELISA) was developed for the detection of serum antibodies to equine arteritis virus (EAV). Results from this assay produced a good correlation with results from virus neutralisation tests in horses which had not been regularly vaccinated with commercially available mammalian tissue culture-derived viral vaccines. Vaccination of some horses with tissue culture-derived vaccines induced the formation of antibodies to bovine serum. These antibodies reacted with the bovine protein contaminants in the EAV ELISA antigen, producing false-positive results. Non-vir...
Zamora CS, Vitums A, Nyrop KA, Sande RD.The heart of a 6-week old Arabian filly with a history of poor health and exercise intolerance revealed at postmortem examination, multiple cardiac malformations which included atresia of the right atrioventricular orifice (tricuspid atresia, with associated atrial and ventricular septal defects), complete transposition of the great arteries, anomalous drainage of the venae cavae and coronary sinus into the left atrium, coarctation of the aorta, and a small but patent ductus arteriosus. The course of blood through the heart was suggested and discussed.
Beroza GA.A device and technique for intra-operative gastro-intestinal lavage was developed to remove ingesta from the stomach, large intestine and caecum of horses. The Gastro-Intestinal Lavage System (GILS) is composed of a nozzle connected to both water under pressure and suction. Water jets across an intake portal in the nozzle, breaks up food and debris within the nozzle and is evacuated under negative pressure into the aspirating tube which is connected to a collection drum. The GILS nozzle was introduced at the pelvic flexure through a sterile enterotomy cuff and plastic sleeve. Water was first a...
Li JK, Moloney BK, Shupe JL, Gardner EJ, Leone NC, Elsner Y.Genomic DNA polymorphisms obtained by restriction fragment-length polymorphism from healthy horses and horses with hereditary multiple exostoses were analyzed. These DNA were digested by 12 restriction enzymes and were hybridized against 6 isotopically labeled oncogene probes. Hybridization was not detected with the viral oncogene, v-ras, which indicated this oncogene was absent in the equine genome. Oncogenes (c-raf-1, c-fes, c-myb, c-myc, and c-sis) were present and had similar hybridization patterns and signal intensities in DNA from healthy horses and horses with hereditary multiple exosto...
Tillman LG, Moore JN.The activity of serum angiotensin converting enzyme (ACE) for healthy horses was 64 +/- 13 mUnits/ml. In vitro, equine serum ACE was sensitive to the following inhibitors (IC50): enalapril (570 nM or 215 ng/ml), captopril (190 nM or 41.3 ng/ml), and enalaprilat (6 nM or 2.1 ng/ml). The intravenous (i.v.) administration of angiotensin I to six healthy horses produced a dose proportional pressor response. The maximal increase in mean arterial pressure over baseline values was 65.6 mmHg at angiotensin I doses of 500 ng/kg bodyweight (bwt). The attenuation of this response to angiotensin I was fur...
Zong E, Fan G.Generally speaking, the majority of F1 hybrids between the horse and donkey are sterile and do conform to the hypothesis of gametogenic breakdown. The results of our own research, nevertheless, lead us to conclude that there is variability in degree of sterility and fertility for both F1 and B1 individuals, with a gradual advance from sterility to fertility being seen. This is the subject we will discuss from the point of view of oestrus, ovulation, mating, pregnancy, spermatogenesis, endocrine activity, isozymes and karyotypic analysis in this paper.
Archer RM, Lindsay WA, Smith DF, Wilson JW.The vasculature of 22 small colons from dead adult ponies was perfused with latex or barium sulphate solution. The vascular anatomy was studied by use of dissection and alkali digestion of the latex specimens and microangiography of the barium sulphate-perfused specimens. The small colon is supplied by the caudal mesenteric artery. The left colic artery arises from the caudal mesenteric artery, which then becomes the cranial rectal artery. Branches from the left colic and cranial rectal arteries form anastomosing arcades that become narrower distally along the length of the small colon. From t...
Cambridge H, Reynoldson JA, Dunsmore JD.Plasma thromboxane B2 (TXB2) the stable inactive metabolite of thromboxane A2 (TXA2), was measured daily by specific radioimmunoassay in three groups of animals before and after experimental infection with Strongylus vulgaris. Infection of four 'parasite naive' foals produced a typical acute syndrome with intermittent but statistically insignificant rises in TXB2 levels. Interpretation of results was complicated by the presence of a non-septic peritonitis associated with implantation of the foals with electrodes for recording myoelectrical activity. In two foals of similar age, with some natur...
Klei TR, French DD, Chapman MR, McClure JR, Dennis VA, Taylor HW, Hutchinson GW.The long-term efficacy of an irradiation attenuated larval (L3) vaccine against Strongylus vulgaris was tested in ponies which were reared on pasture. Prior to foaling, mares were divided into two groups. One group of mares and foals received regular (eight weekly) treatment with ivermectin and the second group remained untreated. Half the foals in each pasture group were vaccinated at eight to ten weeks of age. Foals were weaned at three to four months of age and maintained on separate pastures. At eight to ten months of age, ponies were placed in box stalls and half of each treatment group w...
Ishida N, Katayama Y, Sato F, Hasegawa T, Mukoyama H.The entire cDNA sequences were determined by reverse transcription-polymerase chain reaction (RT-PCR) and rapid amplification of cDNA ends (RACE) techniques for equine copper/zinc superoxide dismutase (Cu/Zn-SOD) and manganese superoxide dismutase (Mn-SOD) through the use of total RNA extracted from the testis of an adult Thoroughbred. The results revealed a protein coding region for equine Cu/Zn-SOD with bases totaling 465 bp, accompanied by an estimated 154 residues of amino acids. As for equine Mn-SOD, its coding region contained a total of 669 bp and an estimated 222 residues of amino acid...
Hinchcliff KW, Byrne BA.Aspects of a detailed examination of the respiratory system of the horse with suspected respiratory system disease are described. This review includes discussions of the terminology of signs associated with respiratory system disease; radiographic examination of the upper and lower airways and thorax; nuclear scintigraphy; percutaneous and endoscopic tracheal aspiration; bronchoalveolar lavage; electromyography; blood gas analysis; and pleuroscopy and pleural fluid examination.
Eustachiewicz R, Flieger S, Boratyński Z, Sławomirski J.The material for the study was taken from 2 spinal cords of sexually mature horses. Preparations obtained from this material were stained according to Nissl and with the use of cresyl violet. The nucleus dorsalis of the horse extends from the 8th cervical neuromere to the 3rd lumbar neuromere of the spinal cord. The cells which form this nucleus lie in the grey matter of the spinal cord, dorsolaterally of the central canal. The nucleus dorsalis is made out of large and medium-size round and oval cells. The characteristic feature of the structure and configuration of this nucleus in the horse i...
Harrison LJ, May SA, Richardson JD, Mills G, Dixon P.Four horses with an incomplete fracture of a hindlimb longbone were examined. In two, the tibia had been fractured by external trauma. In the other two horses proximal metatarsal 3 had fractured during normal activity. The diagnoses were made radiographically and the horses were treated conservatively by box rest. The fractures healed satisfactorily and the horses became sound.
Ball MA, Weldon AD.A 5-year-old Appaloosa gelding was presented with a history of intermittent multiple joint swelling, weight loss, and anemia. Physical examination and clinical pathology revealed a grade IV/VI holodiastolic murmur, louder on the left, and a marked hyperproteinemia. Echocardiography of the heart demonstrated a large vegetative lesion on one of the aortic valve cusps. Blood cultures did not elucidate the causative organism, and the disease was refractory to empiric antibiotic therapy. The horse was euthanized after approximately 2 months of therapy.
Friedman R.The value of providing equine reproductive services in ambulatory setting is well established. Ambulatory practice has been, and will most likely continue to be, the primary provider of equine reproductive veterinary services. The limitations for performing various reproductive procedures in an ambulatory setting are those imposed by the amount of equipment and supplies that must be brought to the patient, as well as those imposed when procedures require additional assistance. This is analogous to human medical care: the ambulance cannot substitute for a hospital but it can certainly provide s...
Parker RA, Bladon BM, Parkin TD, Fraser BS.Increased radio-isotope uptake (IRU) in the subchondral bone of the plantaro-lateral condyle of the third metatarsus (MTIII) is a commonly reported scintigraphic finding and potential cause of lameness in UK Thoroughbred racehorses in training and has not been fully documented. Objective: To characterise lameness attributable to IRU of the subchondral bone of MTIII, compare the scintigraphic findings of these horses with a normal population and evaluate the use of scintigraphy as an indicator of prognosis. Objective: IRU will be in significantly higher in horses with subchondral bone injury an...
Hillidge CJ, Lees P.The neuroleptanalgesic drug combination of
etorphine and acepromazine (Large Animal
Immobilon; Reckitt & Colman Ltd.) was
administered i.v. at the recommended dose rate
(24 ,ug/kg etorphine and 100 pg/kg acepromazine)
to twelve Welsh Mountain ponies of 185 to 336 kg
bodyweight. Cardiovascular measurements were
made before and at pre-determined times up to
30 min after the injection. The etorphine
antagonist, diprenorphine (Revivon; Reckitt &
Colman Ltd.), was then injected i.v. (30,ug/kg)
and further measurements were obtained.
Pronounced increases in heart rate, moderate
increase...
Logas D, Kunkle G, Calderwood-Mays M, Frank L.An 8-year-old gelding, with a 1-year history of intense pruritus only after exercise, was diagnosed as having cholinergic pruritus. Provocative testing, using exercise and hot-water baths to increase core body temperature, assisted in the diagnosis. Cholinergic pruritus in human beings is a variant of the more common syndrome, cholinergic urticaria, which is characterized by intense pruritus and pinpoint urticaria. With cholinergic pruritus, intense itching results without urticaria. Specific diagnostic laboratory tests have not been developed.
Montgomery K, Ortved K, DeVries J, Hackett R, Kern T, Irby N, Ducharme N.A 7-year-old Connemara stallion was presented with a 4 month history of blepharospasm, recurrent corneal ulcerations, mucopurulent ocular discharge, and keratoconjunctivitis sicca (KCS) in both eyes unresponsive to medical therapy. Ophthalmic examination revealed lackluster corneas, axial corneal scarring and pigmentation with associated neovascularization, and absolute KCS in both eyes. Computed tomography scan and endoscopic evaluation of the upper airway and guttural pouches revealed no structural abnormalities to indicate neurogenic KCS. The stallion was diagnosed with immune-mediated dacr...
Brown MP, Gronwall RR, Martinez DS, Beal C.Six healthy pony foals, from 2 to 11 days of age, were given a single IM injection of amikacin sulfate (250 mg/ml) at a dosage rate of 7 mg/kg of body weight. Serum amikacin concentrations were measured serially over a 24-hour period. The mean peak serum concentration was 14.7 micrograms/ml at 0.5 hour. The elimination rate constant for amikacin was 0.24/hour, the elimination half-life was 3.0 hours, and the apparent volume of distribution was 0.58 L/kg.
Grzeskowiak RM, Barrett EJ, Rodgerson DH.An 11-year-old Thoroughbred mare with colic unresponsive to medical treatment underwent exploratory laparotomy. During surgery the cecum was found entrapped within the epiploic foramen from left to right. The entrapped cecum was reduced through the foramen by gentle traction. After reduction of the cecum, rupture of the portal vein was detected. Loss of a large amount of blood prompted euthanasia during surgery. Une jument Thoroughbred âgée de 11 ans atteinte de coliques ne répondant pas au traitement médical a subi une laparatomie exploratoire. Durant la chirurgie, le cæcum a été trou...
Lewis DD.A classification scheme for penetrating joint injuries is presented. Diagnostic techniques and treatment recommendations for managing penetrating joint injuries in small animals are described. Techniques used in human and equine patients are discussed for comparison.
Gift LJ, DeBowes RM.Nonhealing wounds can present a frustrating clinical challenge to the veterinary practitioner. In many cases, healing is delayed by the presence of a foreign body or sequestrum; a review of wounds complicated by the presence of osseous sequestration and penetrating foreign bodies is presented. The typical signs include delayed wound healing and the presence of serous to exudative drainage, which may vary from intermittent to continuous. The use of radiographic or sonographic imaging modalities is often of value in reaching a diagnosis. Removal of the sequestra or foreign body is generally cura...
Townsend WM, Langohr IM, Mouney MC, Moore GE.Based on the current literature, neither medical, surgical nor combination therapy adequately controls equine glaucoma for many horses. Aqueous shunts have been useful in other species to control glaucoma. Objective: To determine whether aqueous shunts in normal equine eyes significantly reduce intraocular pressure (IOP) without causing vision threatening complications. Methods: Prospective experimental trial. Methods: Aqueous shunts were placed in 7 normal eyes of 4 horses. The shunts were placed dorsotemporally. Examinations were initially performed daily for 7 days and after that every 3 da...
Gaynor JS, Bednarski RM, Muir WW.The effect of xylazine on the arrhythmogenic dose of epinephrine (ADE) was studied in 9 horses. Anesthesia was induced by administration of guaifenesin (50 mg/kg of body weight, IV) followed by thiamylal (4 to 6 mg/kg, IV) and was maintained at 1 minimal alveolar concentration (MAC) of halothane (0.89%). Base apex ECG and facial artery pressure were recorded. Epinephrine was infused in a sequence of arithmetically spaced increasing rates (initial rate 0.25 micrograms/kg/min) for a maximum of 10 minutes. The ADE was defined as the lowest epinephrine infusion rate to the nearest 0.25 micrograms/...
Thompson DL, Reville-Moroz SI, Derrick DJ, Walker MP.Sixteen intact cyclic mares were treated on the fourth day of estrus and then every other day for a total of six injections with 1) testosterone propionate, 2) dihydrotestosterone (DHT) benzoate, 3) estradiol (E2) benzoate or 4) safflower oil. Mares were given gonadotropin releasing hormone (GnRH) on Day 3 of estrus (pretreatment) and again 24 h after the last steroid or oil injection. Treatment with testosterone propionate resulted in a greater (P less than 0.05) follicle-stimulating hormone (FSH) response to the second injection of GnRH compared with all other treatments. Treatment with DHT ...