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.
Broadstone RV, Robinson NE, Gray PR, Woods PS, Derksen FJ.The effect of aerosol and intravenous administrations of furosemide was examined in ponies with recurrent obstructive pulmonary disease, commonly called 'heaves'. This recurrent airway disease bears many similarities to human asthma. Six ponies with the disease (principal animals) were studied during clinical remission and during an acute attack of airway obstruction precipitated by stabling and feeding dusty hay. Six control animals were also studied. Furosemide (1.0 mg/kg) or vehicle was administered by aerosol in the first study, and intravenously in a second study. In principal ponies with...
Prescott JF.Recent isolations of Rhodococcus equi from cavitatory pulmonary disease in patients with AIDS have aroused interest among medical microbiologists in this unusual organism. Earlier isolations from humans had also been in immunosuppressed patients following hemolymphatic tumors or renal transplantation. This organism has been recognized for many years as a cause of a serious pyogranulomatous pneumonia of young foals and is occasionally isolated from granulomatous lesions in several other species, in some cases following immunosuppression. The last decade has seen many advances in understanding o...
Roser JF, Hughes JP.Hormonal effects of prolonged administration of gonadotrophin-releasing hormone (GnRH) were investigated in 7 fertile stallions in winter and summer. The stallions were divided into 4 groups so that 1 animal received 0.625 micrograms of GnRH and each of 2 animals received 1.25, 2.5 or 5.0 micrograms of GnRH subcutaneously every 30 min for 5 days. Daily blood samples were collected from 5 days before to 5 days after treatment for measurement of plasma concentrations of luteinizing hormone (LH), follicle stimulating hormone (FSH), testosterone (T) and oestrogen conjugates (EC). Five-minute blood...
Cothran EG, Henney PJ, King JA.The inheritance of the equine Tf F3 allele was examined in 39 parent-offspring combinations. For 26 of the cases the allele inherited by the offspring from the heterozygous parent could be determined. The proportion of individuals that inherited the F3 variant compared to the alternative allele was exactly 1:1. In five cases the parental phenotype was identical to that of the offspring. For the remaining eight cases the parent was homozygous for the F3 allele and all offspring had the F3 allele. The results were consistent with Mendelian inheritance.
Guillaume D, Palmer E.Two experiments tested the hypothesis that exogenous melatonin (12 mg) given 4 h before dusk (evening melatonin), or near dawn (morning melatonin), would mimic a prolongation of the night and suppress stimulation of the ovaries induced by long days. Experiment 1 consisted of a non-stimulated control group, a control group stimulated by 14.5 h of light, a treated group stimulated with 14.5 h of light plus evening melatonin, a control group given 17.5 h of light and a treatment group given 17.5 h of light plus morning melatonin. The mean (+/- s.e.m.) intervals from the start of treatment to the ...
Baxter GM, Adams JE, Johnson JJ.Severe hypercarbia was documented by arterial blood gas analysis in 2 adult horses anesthetized for exploratory laparotomy. Both horses appeared to be adequately anesthetized, but continued to breathe against the ventilator. In both cases, the inspiratory valve on the anesthesia machine was found to be stuck open, permitting expired CO2 to return to the inspiratory limb of the anesthetic circuit and to be inhaled with the next breath. Correction of the malfunctioning valve alleviated the hypercarbia. Problems with the flow valves of the anesthesia machine should be suspected when anesthetized ...
Pantke P, Hyland J, Galloway DB, MacLean AA, Hoppen HO.Equine plasma luteinizing hormone (LH) possesses both biological (in vitro bioassay, B) and immunological (radioimmunoassay, I) activities and the ratio of B:I varies with stage of the oestrous cycle. To estimate the contribution made by pituitary secretion and peripheral metabolism to changes in the B:I ratio, pituitary venous effluent and circulating plasma from 5 dioestrous and 2 oestrous mares were analyzed using both an in vitro bioassay and a radioimmunoassay. During dioestrus, LH was released in a pulsatile fashion with a frequency of 1.4 pulses/24 h and a pulse duration of 20-40 min (c...
Boermans HJ, Johnstone I, Black WD, Murphy M.Six horses gavaged with a commercial brodifacoum (BDF)-containing bait (Talone) at a dosage of 0.125 mg of BDF/kg of body weight showed weight loss, severe hypocoagulability and hemogram alterations. Four of the horses became depressed and anorectic; one required vitamin K1 therapy. Increases in clotting times were observed at 24 h in the partial thromboplastin time (PTT) followed by the thrombotest (TBT) and one-stage prothrombin time (PT) at 48 h. Elevated mean PTT, PT and TBT were observed from days 4 to 8 (p less than 0.05) with levels returning to pretreatment levels by day 12. Maximum pr...
Cain PW, Jones JH, Smith BL.A remote data sampling cart has been designed and built for studying environmental factors that produce stress in horses during transportation. This dedicated sampling cart uses an XT-compatible mother board powered by a 12 V battery, with customized BIOS and ROM program. Sampling is performed using two digital and eight A/D (bipolar, differential) channels in burst mode at a frequency of 1 kHz. Digitized data are stored on magnetic tape for retrieval after the experiment. Configuration of sampling parameters is accomplished via a serial communications link to a host computer, and is stored in...
Ross MW, Orsini JA, Richardson DW, Martin BB.Infectious arthritis of the tarsocrural joint was treated in 13 horses with closed suction drainage through a flat, fenestrated, latex (Jackson-Pratt) drain, broad-spectrum antimicrobial agents, nonsteroidal anti-inflammatory drugs, and bandage immobilization. In 11 horses, arthroscopic lavage and debridement were also performed. Ingress drains were placed for lavage in six horses. Ten horses returned to their previous level of competition or were sound. One horse raced but had lameness of the affected tarsocrural joint and dropped in racing class; one horse was euthanatized because of laminit...
Eysker M, Boersema JH, Kooyman FN.Two groups of three ponies were used to study the effect of three ivermectin or pyrantel treatments given at intervals of 5 weeks at the beginning of the grazing season. Although each pyrantel treatment resulted in a greater than 95% reduction in faecal egg counts during the first 3 weeks, high pasture larval counts were seen from the beginning of August onwards and substantial cyathostomine burdens were found at necropsy in December. The ivermectin treatments resulted in an even more pronounced reduction in faecal egg output, and the pasture larval counts and cyathostomine burdens at necropsy...
al-Bagdadi F, Hoyt P, Karns P, Martin G, Memon M, McClure R, McCoy D, Shoemaker S.Eleven unilateral cryptorchid stallions, two to three years old, were castrated at Louisiana State University Veterinary Teaching Hospital. Five of these cryptorchid cases were abdominal and the rest were inguinal. This study was initiated to document the differences between the abdominal and inguinal equine cryptorchid testes. Specimens were obtained from the abepididymal side of each cryptorchid testes and processed for light and electron microscopic study. The cryptorchid testes were smaller than the scrotal testes, with the abdominal testes being one-fourth the size of the scrotal testes. ...
Pellegrini A, Waiblinger S, Von Fellenberg R.Lysozyme from equine neutrophil granulocytes was isolated in a pure form by fast performance liquid chromatography, i.e. ion-exchange chromatography and reversed-phase chromatography. The lysozyme lysed Micrococcus luteus, Bacillus subtilis and Staphylococcus lentus and was also bactericidal against the Gram-negative bacteria Escherichia coli, Klebsiella pneumoniae, Bordetella bronchiseptica, and Serratia marcescens. Staphylococcus aureus and Staphylococcus epidermidis were not lysed. The lysozyme was only very slightly bactericidal for S. epidermidis and S. aureus. Equine neutrophil lysozyme ...
Vallejo AN, Miller NW, Clem LW.This work was undertaken to investigate whether or not antigen processing and presentation are important in channel catfish in vitro secondary immune responses elicited with structurally defined proteins, namely, pigeon heart cytochrome C (pCytC), hen egg lysozyme, and horse myoglobin. The use of in vitro antigen-pulsed and fixed B cells or monocytes as antigen presenting cells (APC) resulted in autologous peripheral blood leukocytes (PBL) responding with vigorous proliferation and antibody production in vitro. In addition, several long-term catfish monocyte lines have been found to function a...
Lees MJ, Fretz PB, Bowen CV, Leach DH.Equine limb wounds often heal slowly by epithelialization, and large scars are a frequent end result. In some ways, they resemble the wound associated with human tibial injuries. The literature indicates that previous investigators have failed to transfer free skin flaps successfully in the horse. In this paper, we review our experimental work with the deep circumflex iliac flap in the horse. Dissections of 20 cadavers confirmed the anatomical consistency of the flap. Four flaps survived well when elevated as island flaps, but five orthotopic and nine heterotopic free flap transfers all failed...
Fowden AL, Mundy L, Ousey JC, McGladdery A, Silver M.Glycogen and glucose 6-phosphatase levels were measured in a variety of tissues from fetal, newborn and adult pregnant mares. Hepatic and renal glucose 6-phosphatase activities increased with increasing gestational age and rose further in the 24 h after birth to values similar to those observed in maternal tissues. The glycogen content of fetal liver and skeletal muscle also increased in late gestation, whereas that of fetal lung and cardiac muscle decreased toward term. No significant change in renal glycogen content with fetal age was observed. The values of hepatic glycogen and glucose 6-ph...
Hunt RJ, Allen D, Baxter GM, Jackman BR, Parks AH.Deep digital flexor tendon transection at the mid-metacarpus was performed in 20 horses with severe acute or chronic laminitis that was not responsive to conventional treatment. Sixteen horses improved within 72 hours, one horse worsened, and two horses were unaffected by the surgery. Eleven horses survived less than 1 month after surgery and six horses survived longer than 6 months. Three horses surviving longer than 6 months have remained lame and no horse has returned to athletic performance. Transection of the deep digital flexor tendon at the mid-metacarpus may decrease the pain associate...
Hermanson JW, Hegemann-Monachelli MT, Daaod MJ, LaFramboise WA.The biceps brachii of horses is subdivided into a lateral and medial head. Electrophoresis of samples from the lateral head revealed three slow-migrating native myosin isoforms, including one that does not correspond to slow myosin isoforms described for other mammalian muscles. In contrast, the medial head contained a single slow isoform. Both the lateral and medial heads contained three fast-migrating isoforms corresponding with the FM-2, FM-3 and FM-4 isoforms reported for other mammalian fast-twitch muscle fibers. Electrophoresis of myosin heavy chains (MHCs) revealed only two MHC bands, o...
Angelos JA, Marti E, Lazary S, Carmichael LE.The DNA from equine sarcoid samples from New York State and Switzerland was isolated and probed with bovine papillomavirus type 1 (BPV-1) to determine if BPV genomes were present. Twelve of 13 sarcoids from New York State and 17/20 sarcoids from Switzerland contained DNA that hybridized to the BPV-1 probe. Restriction enzyme analysis of the positive samples demonstrated restriction fragment profiles characteristic of BPV-1 in 22 sarcoids and restriction fragment profiles characteristic of bovine papillomavirus type 2 (BPV-2) in 7 sarcoids. In addition, three tissues histologically diagnosed as...
Brooks M, Leith GS, Allen AK, Woods PR, Benson RE, Dodds WJ.Bleeding diathesis in a Quarter Horse filly was caused by von Willebrand disease. Hemorrhage occurred mainly from mucosal surfaces and after trauma. Quantitative and qualitative measurements of plasma von Willebrand factor (vWF) documented a specific deficiency of vWF high molecular weight multimers, and concurrently greater than expected deficiency of vWF activity relative to vWF concentration. These findings are characteristic of type-II von Willebrand disease in human beings. Application of vWF assays used in human and small animal medicine now permits evaluation of vWF and diagnosis of von...
Clark ES, Gantley B, Moore JN.The effects of intravenous (iv) infusion of endotoxin for 60 mins at a cumulative dosage of 0.03 micrograms/kg bodyweight on systemic arterial, right atrial and pulmonary arterial pressures, heart rate, cardiac output, and derived pulmonary vascular resistance and total peripheral vascular resistance were compared to the effects of iv infusion of saline solution in four healthy horses. Heart rate was increased significantly after endotoxin infusion, although diastolic arterial pressure, systolic arterial pressure, electronically averaged arterial pressure, cardiac output, total peripheral resi...
Broadstone RV, LeBlanc PH, Derksen FJ, Robinson NE.The in vitro contractile and relaxant responses of tracheal smooth muscle strips (TSM) and third-generation bronchi (3B) of control horses and horses with recurrent obstructive disease (heaves) were compared. Acetylcholine (ACH) sensitivity of the diseased tissues was less than that of tissues from control horses, especially at the level of the third generation (EC50 controls 15 +/- 11 microM vs 81 +/- 17 microM for heaveys). Despite tracheal and bronchial hyporesponsiveness to ACH, these tissues from heavey horses were hyperresponsive to EFS. The inhibitory effect of isoproterenol and electri...
Riley CB, Yovich JV.Fractures of the patella in the horse are infrequently reported
in the literature. Most of these have been associated with trauma
or sudden forceful contraction of the quadriceps resulting in an
avulsion fracture of the patella (Parks and Wyn-Jones 1988).
There have been few reports of fractures associated with des-
motomy of the medial patellar ligament to correct upward
fixation of the patella (Wright and Rose 1989; Gibson ef ul1989).
This paper describes one such case including the radiographic
findings before the desmotomy, after fracture of the patella and
after arthroscopic trea...
Weitkamp LR, Kenney RM, Bailey E, MacCluer JW, Brown JS, Blanchard TL, Sertich PL, Love CC, Hunt PR.Histological features of the endometrium, as assessed in biopsy samples, were related to Standardbred mare genotypes for transferrin, esterase (as a control) and equine leucocyte antigens (ELA). Pathological changes were found more frequently in each successively older age group of mares. Among mares aged 6-19 years, there were significant pathologic changes on first examination following an infertile breeding season for 46 of 90 (51%) of transferrin homozygotes and 50 of 146 (34%) of transferrin heterozygotes. The difference between the two groups was significant for the total data (chi 1(2) ...
Trotter GW, McIlwraith CW, Yovich JV, Norrdin RW, Wrigley RH, Lamar CH.The effects of the corticosteroid 6-alpha-methylprednisolone acetate on normal equine articular cartilage were evaluated, using the middle carpal joint in 4 clinically normal young horses. One middle carpal joint of each horse was injected 3 times with 100 mg of 6-alpha-methylprednisolone acetate, at 14-day intervals. The opposite middle carpal joint (control) was injected with 2.5 ml of lactated Ringer solution at the same intervals. Effects were studied until 8 weeks after the first injection. Evaluation included clinical and radiographic examination, and gross, microscopic, and biochemical ...
Zhang JJ, Muzs LZ, Boyle MS.Three experiments were conducted to assess the structural and functional changes of stallion spermatozoa in response to the calcium ionophore A23187, and to determine individual variation between stallions. In Experiment 1, changes in the acrosome of spermatozoa exposed to 7.14 microM A23187 for fixed times between 0 and 120 min were examined. There was a steady increase with time in the number of spermatozoa undergoing the acrosome reaction although the rate of increase differed between stallions. Sperm motility decreased sharply when incubation was extended beyond 30 min. In Experiment 2, th...
Blanc G, Magistrini M, Palmer E.Semen from three ejaculates from each of 4 stallions was frozen in liquid nitrogen. Morphology was evaluated by coating the spermatozoa with fluorescein-labelled Concanavalin A (FITC-ConA2) and motility was measured by computer-assisted image analysis. Coating was performed at each step of the freezing procedure (dilution, cooling, addition of glycerol and freeze-thawing) and observations were made after each step, to evaluate changes, or after subsequent steps, to determine protection provided by the coating method. All the parameters showed progressive changes during the freezing procedure. ...
Trout DR, Hornof WJ, O'Brien TR.Radiography and soft tissue- and bone-phase scintigraphy were performed on 14 clinically normal horses and 35 horses in which definite, probable, or possible navicular disease had been diagnosed. The specificity of radiography and scintigraphy in revealing signs of navicular disease were nearly equal; however, the sensitivity of scintigraphy appeared to be greater than that of radiography. The greatest sensitivity and specificity were achieved when the results of radiography and scintigraphy were evaluated together. Differences in sensitivity were greatest when scintigraphy revealed lesions no...
McCool CJ, Gilfedder J.This study explores a rare case where an equine disease was found to be caused by Salmonella anatum, an organism typically associated with cattle, in a week-old foal and its […]
Noschka E, Moore JN, Peroni JF, Lewis SJ, Morrow JD, Robertson TP.Inflammation and vascular dysfunction occur concurrently during the prodromal stages of equine laminitis. The aim of this study was to provide insights into the role that thromboxane and isoprostanes may play in the development of black walnut heartwood extract (BWHE)-induced laminitis. Horses were divided into two groups, either control or BWHE-administered horses. Plasma concentrations of thromboxane increased transiently after administration of BWHE and coincided with the nadir in white blood cell counts, whereas plasma concentrations of iso-prostaglandin PGF(2alpha) (iso-PGF(2alpha)) did n...
Kidd JA, Dyson SJ, Barr AR.Intratendonous infection in the absence of any clinical evidence of a wound has not, to our knowledge, been described previously in horses. This paper reports the clinical features, diagnostic techniques. treatment and outcome in 5 cases of septic flexor tendon core lesions. This condition is characterised by seven lameness and ultrasonographic evidence of a central intratendonous anechoic core lesion which may enlarge rapidly.
Campbell-Thompson M.The goals of surgical therapy in foal gastroduodenal ulcer disease are the elimination of abdominal pain, healing of mucosal ulcerations, and prevention of complications. Gastrojejunostomy has been used with success in both pyloric and duodenal ulcerations that have progressed to gastric outflow obstruction. Gastrojejunostomy has resulted in rapid healing of gastritis and esophagitis and resolution of aspiration pneumonia and biliary stasis without recurrence of duodenal ulceration.
Henry JS, Lance VA, Conlon JM.Within the order Perissodactyla, the primary structure of insulin has been strongly conserved. Insulin from Przewalski's horse and the mountain zebra (suborder Hippomorpha) is the same as that from the domestic horse and differs from insulin from the white rhinoceros and mountain tapir (suborder Ceratomorpha) by a single substitution (Gly-->Ser) at position 9 in the A-chain. A second molecular form of Przewalski's horse insulin isolated in this study was shown to represent the gamma-ethyl ester of the Glu17 residue of the A-chain. This component was probably formed during the extraction of the...
Alexander RM.This research presents the hypothesis and findings that short muscle fibers in horses and other large mammals may protect bones and tendons from damaging vibrations during running, negating the previous […]
Kruger K, Saulez MN, Neser JA, Solberg K.Lead (Pb) intoxication in horses is usually a chronic phenomenon with clinical signs associated with central nervous dysfunction. This report gives details of a case of acute Pb intoxication in a 9-year-old American Saddlebred mare with severe, progressive and ultimately fatal neurological deterioration. During the 4 days of hospitalisation, clinical signs progressed from intermittent headshaking and depression to severe, continuous, uncontrollable manic behaviour. At autopsy, three grey-coloured, hard metal particles were present in the gastrointestinal tract and subsequently found to contain...
Townsend KS, Johnson PJ, Donnelly LL, LaCarrubba AM, Lattimer JC, Havis B, Springer NL, Kim DY.A 26-year-old mule gelding was evaluated for chronic weight loss and decreased appetite. The mule had been losing weight and intermittently hypophagic for approximately 7 months. Laboratory analysis of whole blood and plasma identified severe total hypercalcemia, marked hypophosphatemia, markedly increased parathyroid hormone concentration, and marked lymphocytosis. A sestimibi scan intended to identify parathyroid gland tissue was nondiagnostic. Results of flow cytometry and PCR for antigen receptor rearrangement (PARR) were consistent with a B cell lymphoproliferative disorder, likely chro...
Klomkleaw W, Kasashima Y, Kobayashi A, Fuller GA, Morimoto M, Nakade T, Muto M, Oba T, Hamlin RL, Yamaguchi M.Tubular aggregates (TAs) originate from the sarcoplasmic reticulum (SR) and form polymorphic double (or single) -walled structures in cross section. TAs are involved in various human skeletal muscle disorders including periodic paralysis, congenital myasthenic syndromes, inflammatory myopathies, and malignant hyperthermias. Horse lumbrical muscle (LM) is a slender fusiform muscle that shows varying degrees of regression due to its limited activity in the limb. Double-walled TAs were found in degenerating spindle fibers and with a range of 80-116 nm (average 92 nm, n=135) for outer layer and 50...
Beeman GM, Soule SG, Swanson TD.This article reviews the history of the medical evaluation of the horse for purchase and the gradual development of definitions and guidelines for performing such an examination. The philosophy of pre-purchase examinations, including potential conflicts of interest, recording methods, and procedures, is discussed. The AAEP guidelines for reporting purchase evaluations are also included.
Hudson NP, Pearson GT, Mayhew IG.Ileal samples were harvested fresh from euthanized adult horses. The tissues were microdissected to prepare wholemount preparations for immunohistochemistry and for either explant or dissociated culture systems of the enteric nervous system. Explant culture systems were established using whole-mounts of either the submucous plexus or the muscularis externa (including the myenteric plexus). Dissociated cell cultures could only be obtained from the submucous plexus. Culture systems were maintained for up to 5 days. Immunoreactivity for a neuronal marker (Pan-N) and for glial cell markers (GFAP a...
Coleman RJ, St Lawrence AC, Lawrence LM, Roberts AM.This study was conducted to compare bodyweight (bwt) loss and recovery in Standardbred horses receiving frusemide compared to controls. Thirty Standardbred horses from 7 training stables that were racing at the Red Mile in Lexington, Kentucky, during the spring 2001 pari-mutuel meeting were studied. Fourteen horses (FRU) received frusemide (250 mg/horse i.v.) 4 h prior to racing, while 16 horses (NFRU) did not received frusemide. Horses were weighed on the morning of race day, prior to warm-up, after racing and the next day. Changes in bwt were calculated as percentage increase or decrease fro...
Wilson DV, Berney CE, Peroni DL, Mullineaux DR, Robinson NE.Acupuncture may be recommended for horses with 'heaves' because it is being increasingly applied to treat human asthma. Therefore, its efficacy was investigated in horses with this asthma-like disease. Objective: To evaluate the efficacy of a single acupuncture treatment for the relief of airway obstruction in heaves-affected horses. Methods: The efficacy of a single acupuncture treatment was tested in 10 heaves-affected horses, and the effect of removal from the dusty stall environment in 5 heaves-affected horses. Before treatment, horses were stabled to induce airway obstruction and, apart f...
Hillidge CJ, Lees P.The effects of thiopentone-halothane and thiopentone-ether anaesthesia on left ventricular isotonic function were assessed in Welsh Mountain ponies from measurements of left ventricular stroke work, minute work, stroke power, mean ejection rate and tension-time index.
All of these variables were affected similarly during anaesthesia, an initial marked reduction being followed by a progressive return towards control levels in the later stages of anaesthesia. Quantitative differences between the effects of each agent were evident, the depression which occurred during halothane anaesthesia bei...
Cohen ND, Hu Z, Stanley SD, Wang N.Furosemide is frequently used to control or prevent exercise-induced pulmonary hemorrhage in performance horses. The bronchodilating agent clenbuterol is also commonly used as a treatment for inflammatory airway disease in performance horses. Use of both medications is regulated by many racing authorities. The effects of concomitant administration of furosemide and clenbuterol on the pharmacokinetics of clenbuterol have not been well characterized. A study was designed to evaluate the influence of furosemide on serum and urine concentrations of clenbuterol after oral administration of clenbute...