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.
Kydd J, Antczak DF, Allen WR, Barbis D, Butcher G, Davis W, Duffus WP, Edington N, Grünig G, Holmes MA.The First International Workshop on Equine Leucocyte Antigens was organized and convened for the purposes of identifying immunologically relevant cell surface molecules of equine leucocytes and establishing a system of nomenclature for those molecules. Participating members of the workshop represented the majority of laboratories world-wide engaged in the tasks of production and characterization of equine leucocyte and lymphocyte markers using monoclonal antibodies. The workshop confirmed the identification of several equine CD molecules described previously by individual laboratories, and in ...
King CM, Evans DL, Rose RJ.Various cardiorespiratory and metabolic indices were assessed during treadmill exercise in Thoroughbred and Standardbred racehorses with T wave changes in 4 or more leads on the electrocardiogram or second-degree atrio-ventricular (AV) block, and in horses that had no abnormalities on clinical examination, resting electrocardiography or upper respiratory tract endoscopy. No significant differences in heart rate, plasma lactate concentration, arterial blood gases, oxygen uptake, run time, peak velocity, or blood and red cell volumes were found between normal horses and horses with T wave change...
Erichsen DF, Aviad AD, Schultz RH, Kennedy TJ.A field study of 239 horses was conducted to determine the efficacy and safety of clenbuterol HCl, a beta 2-adrenergic bronchodilator, when administered incrementally to effect in the treatment of chronic obstructive pulmonary disease (COPD). The severity of COPD (heaves) and response to treatment was determined by clinical evaluation; an overall 'heaveiness rating' (OHR) was assigned at each observation. The horses were treated orally b.i.d. with clenbuterol (as Ventipulmin Syrup), beginning with the lowest dosage of 0.8 micrograms/kg. On day 10 of treatment at the effective dose (0.8, 1.6, 2...
Peloso JG, Schumacher J, McClure SR, Crabill MR, Hanselka DV, Householder DD, Potter GD.A T-cannula was fitted permanently into the ileum of ten mature ponies to quantify the role of the prececal and postileal segments of the digestive tract in equine nutrition studies. The ponies were anesthetized, positioned in left lateral recumbency, and the distal small intestine was exteriorized through a right paralumbar incision. A silastic T-cannula was inserted through a 2-cm longitudinal incision into the lumen of the ileum, on the antimesenteric surface, and sutured to the ileum. The stem of the cannula was exteriorized through a 2-cm circular skin incision, 6 cm caudal to the 16th ri...
Forster HV, Erickson BK, Lowry TF, Pan LG, Korducki MJ, Forster AL.Two questions were addressed in this study: 1) Does respiratory resistive unloading (inspired O2 fraction = 0.21, inspired He fraction = 0.79) elicit a compensatory reduction in stimulation of the diaphragm? 2) Do diaphragm and lung afferents contribute to compensatory responses to unloading? Ten intact (I), five diaphragm-deafferented (DD), four hilar nerve-denervated (HND), and seven DD+HND adult ponies were studied at rest and during mild and moderate treadmill exercise. During steady-state unloading at rest, duration of the diaphragm electromyogram (EMGdi) was less (P < 0.05) than contr...
Rich FR, Glisson RR.In vitro failure modes and mechanical properties of the equine cranial cruciate ligament (CCL) were evaluated in 15 stifle joints from 10 ponies. Ponies were from 3 to 25 years of age and weighed from 122 to 208 kg. Femur-CCL-tibia specimens were mounted in 48 degrees of flexion, distracted until a 500-g tensile preload was achieved, and then tested by tensile loading to failure. Specimens failed by complete midsubstance CCL rupture (n = 9), combined tibial insertion avulsion fracture and midsubstance CCL rupture (n = 4), and combined femoral origin avulsion fracture and midsubstance CCL ruptu...
Schneider RK, Ragle CA, Carter BG, Davis WE.Osteochondral fragments detected in the proximal interphalangeal joint in the pelvic limbs of 3 horses (2 Standardbreds and 1 Thoroughbred) caused joint enlargement and lameness. Fragments were removed by use of arthroscopy. Accurate placement of the arthroscope into the dorsal joint space was necessary to obtain an adequate view of the fragments. After surgery, 2 of the horses resumed racing without joint problems, and the third was in training to race. High-detail radiographs are necessary to detect osteochondral fragments in horses with joint enlargement or lameness localized to the proxima...
Von Wittke P, Lindner A, Deegen E, Sommer H.In this study the effects of training history on the results of a standardized two-speed test in competing Thoroughbreds were investigated during a racing season. For nine Thoroughbreds, 1,755 training days were recorded. Within the observation period each horse completed a two-speed field test at intervals of 6-8 wk to determine its running velocity (v) eliciting blood lactate concentrations of 4 (v4) and 12 mmol/l (v12). Horses performed 29 two-speed tests. Changes of v4 and v12 in a horse between two consecutive tests were used to assess effects of training history variables calculated for ...
Frankeny RL, Johnson PJ, Messer NT, Keegan KG, Corwin LA.A 7-month-old Appaloosa foal had bilateral hind limb lameness and was unable to rise from recumbency without assistance. Lameness could be exacerbated by tarsal flexion and a firm swelling at the distomedial aspect of the tibias was associated with a marked pain response when palpated. Radiography revealed enlargement of the distal tibial metaphysis physis (compared with normal), and radiolucent fissure lines extending proximally from the physis into the metaphysis at its medial aspect. Treatment included rest and dietary adjustment. Although clinical signs initially resolved following treatme...
Moore KH, Dunbar BS, Bousfield GR, Ward DN.Inhibin has been characterized from a number of mammals; however, it has not been extensively studied in horses. Western blot analysis was used to examine the size heterogeneity of equine inhibin alpha- and beta-subunits. The distribution of equine inhibin activity from the initial sizing column (S-200, 25 x 94 cm) indicated that the majority of equine inhibin activity was present as larger-molecular-size forms. When the large forms were analyzed by Western blot in nonreducing conditions, alpha-subunit bands were detected at 40,000 M(r), 56,000 M(r), 80,000 M(r), and 90,000 M(r); beta a reacti...
Miles CA, Wardale RJ, Birch HL, Bailey AJ.Differential scanning calorimetry (DSC) of equine superficial digital flexor tendons revealed the presence of a small exothermic peak at 23 degrees C of unknown origin, and a large endothermic peak at 70 degrees C due to denaturation of cross-linked collagen fibres. In the central degenerated core of damaged tendons the denaturation temperature remained at 70 degrees C but the enthalpy decreased in relation to the extent of degeneration of the tendon. We suggest that this reduction in enthalpy is due to depolymerisation and denaturation of the collagen fibres. This contention is supported by t...
Orme CE, Dunnett M, Harris RC.The primary aim of this study was to examine the within-day variation in the concentration of total and individual long chain free fatty acids (C > 14) in normally fed horses. Plasma samples were collected over a 24 h period from 12 resting horses during three separate sessions (six horses in the first session and three in the second and third). Samples were analysed for individual long chain free fatty acids (FFA) and glucose. During normal feeding, the predominant FFA in plasma were palmitic (C16:0), linoleic (C18:2), oleic (C18:1), stearic (C18:0) and linolenic (C18:3). Together these ac...
Molyneux GS, Haller CJ, Mogg K, Pollitt CC.In the foot of the horse, arteriovenous anastomoses (AVAs) of epithelioid type occurred in the dermis of the coronary band, in the coronary and terminal papillae, in neurovascular bundles and at the entrance to and along the length of the dermal laminae. A particular feature of the epithelioid segment of AVAs in the horse, compared with that of other species, was the height and surface complexity of many of the endothelial cells. They extended into the lumen, forming undercut and tunnel-like areas which correlated with the characteristic surface marking of AVAs observed in vascular casts. The ...
Freeman DE, Donawick WJ, Klein LV.The effect of a single ligature on back pressure in the internal carotid artery was studied in nine horses. In six anesthetized horses, one internal carotid artery was catheterized 2 cm from its origin and blood pressure was recorded continuously. Then the artery was ligated, pressure was recorded again, and the horses were euthanatized. In another three anesthetized horses, indwelling catheters were placed in both internal carotid arteries and a loose ligature was placed proximal to one catheter. After horses recovered from anesthesia, the ligature was tied and blood pressure was recorded in ...
Brown SA, Dusza K, Boehmer J.A relation exists between colloid osmotic pressure (pi) and serum total protein concentration; equations describing this relation have been used to determine a calculated value for pi. However, the relation between total protein concentration and pi is altered by the method used to measure protein and by changes in the ratio of concentrations of albumin (A) to globulin (G). We developed nomograms for estimating pi from A and G concentrations, using samples obtained from clinically normal animals and compared the accuracy of these nomograms with that of previously described equations relating p...
Jones DL, Barber SM, Jack SW, Doige CE.Gross and microscopic effects of arthroscopic partial synovectomy on synovium and articular cartilage of middle carpal joints were studied in 15 horses. A 7-mm diameter motorized synovial resector was inserted into each middle carpal joint and arthroscopic partial synovectomy and lavage or arthroscopic lavage alone was performed. Study periods were 0 (three horses), 16 (three horses), and 30 days (six horses). No gross evidence of degenerative joint disease was observed at day 16 or 30. At 30 days, resected areas lacked villi and there was deposition of fibrin on the synovial surface with vary...
Scudamore CL, Pemberton AD, Miller HR, McDonnell AM, Thomson SR, Dawson A, Watson ED.An enzyme linked immunosorbent assay (ELISA) was developed and used to estimate the concentrations of the serine proteinase inhibitor, alpha-1 proteinase inhibitor (API), in uterine flushings recovered from mares at different stages of the oestrous cycle and before and after the induction of experimental endometritis. There was a significant increase in the concentrations of API and albumin relative to total protein in flushings recovered during oestrus compared with dioestrus but no difference was observed in the concentrations of these proteins relative to total protein before and after the ...
Durando MM, MacKay RJ, Linda S, Skelley LA.Polymyxin B and an antiserum against an Re mutant Salmonella typhimurium were evaluated for protective effect in an equine model endotoxemia. Six 3- to 5-month-old foals were given endotoxin (0.25 micrograms/kg of body weight) IV after no pretreatment, or pretreatment with polymyxin B (6,000 U/kg, IV) or S typhimurium antiserum (1.5 ml/kg, IV). When given without pretreatment, endotoxin caused transient recumbency and increases in rectal temperature, and heart and respiratory rates. In addition, leukopenia and increases in circulating tumor necrosis factor (TNF) and interleukin 6 (IL-6) activi...
MacDonald DG, Morley PS, Bailey JV, Barber SM, Fretz PB.Post operative surgical wound infection rates were determined 452 cases of equine orthopaedic surgery performed at the Western College of Veterinary Medicine, Saskatoon, Saskatchewan, between January 1, 1981 and December 31, 1990. Only surgical procedures classified as clean or clean-contaminated by the National Research Council were included in this study. The overall post operative infection rate was 10.0% (45 of 452). Clean surgeries (n = 433) had an 8.1% infection rate while clean-contaminated surgeries (n = 19) had a 52.6% infection rate. Information collected from the medical records was...
Platt D, Bayliss MT.The effect of human recombinant interleukin-1 beta (rhIL-1 beta) on proteoglycan metabolism was investigated in cultures of full thickness explants of articular cartilage from horses 3-21 years of age. Proteoglycan synthesis was inhibited at all ages but no alteration in the hydrodynamic size or electrophoretic heterogeneity was observed in proteoglycan isolated from rhIL-1 beta stimulated cartilage. The sulphation pattern of the newly synthesised proteoglycan molecules was, however, significantly affected by the presence of the peptide regulatory factor. Interleukin-1 had no effect on the rat...
Roger T, Bardon T, Ruckebusch Y.The electrical and mechanical activity of the large intestine and its response to administration of opiate mu and kappa agonists were assessed from electrodes and inductograph coils chronically implanted on the cecocolic segment in six ponies given a diet of hay and concentrates. Before the drugs were given, migrating complexes propagating from the cecum into the colon occurred at the rate of 1.5 to 16/hour. During this propulsive activity, the cecocolic sphincter opened and closed allowing the outflow of cecal contents and preventing the backflow of colic contents. Each pony was used as its o...
Bernoco MM, Liu IK, Willits NH.Six foals were deprived of colostrum for the first 36 hours after birth and, instead, received reconstituted powdered milk. Five control foals suckled their dams naturally. Blood samples were obtained from all the foals after birth and at approximately weekly intervals until at least 5.5 months of age. Sera were analyzed for hemolytic complement activity, complement component C3, and correlating IgG concentration. Hemolytic complement (P = 0.0145) and C3 (P = 0.0002) values were significantly higher in colostrum-deprived foals (CDF) than in naturally nursed foals at 2 to 5 days of age. In addi...
Zhang CH, Donaldson WL, Antczak DF.A surface antigen of equine B lymphocytes was identified using the Equine Leucocyte Antigen Workshop antibody WS 65. This marker was expressed on almost all equine B cells, but not on T cells, granulocytes or thymocytes. WS 65 strongly stained cells in the follicular areas of lymph nodes and cells in the splenic nodules when tested on frozen tissue sections by immunohistochemistry. Equine leukemic T cells were not labeled by WS 65, and neither were the cells from a horse with B cell leukemia, although these latter cells carried surface immunoglobulin. Immunoprecipitation of lymphocyte membrane...
Antonioli ML, Canola PA, de Carvalho JRG, Fonseca MG, Ferraz GC.It is important to understand the effects of hoof trimming on hoof and limb conformation to maximize its benefits on the health of the appendicular skeleton of horses, thus promoting improvements in athletic performance and sporting longevity with regard to athletic horses. There is little information on possible changes in the angulation of the thoracic limb joints after hoof trimming and correlations between the angulation of the thoracic limb joints with hoof measurements. To that purpose, nineteen Mangalarga mares received routine hoof trimming. Visual recordings (photographs) were taken b...
Ahearne MM, Pentzke-Lemus LL, Romano AM, Larsen ED, Watson AM, O'Fallon EA, Landolt GA.Equine influenza virus is a common cause of respiratory disease in equids. Few reports describe clinical presentation and disease progression in donkeys. Objective: Describe the clinical and diagnostic findings, outcome, and pathologic lesions associated with influenza pneumonia in donkeys. Methods: Thirteen unvaccinated donkeys ranging from 1 week to 12 years of age and sharing clinical signs and exposure history. Methods: Retrospective case series. Medical records from June to July 2020 at the Colorado State Veterinary Teaching Hospital and collaborating referring veterinary practices wer...
Verhaar N, Hoppe S, Grages AM, Hansen K, Neudeck S, Kästner S, Mazzuoli-Weber G.α2 agonists are frequently used in horses with colic, even though they have been shown to inhibit gastrointestinal motility. The aim of this study was to determine the effect of dexmedetomidine on small intestinal in vitro contractility during different phases of ischaemia. Experimental segmental jejunal ischaemia was induced in 12 horses under general anaesthesia, and intestinal samples were taken pre-ischaemia and following ischaemia and reperfusion. Spontaneous and electrically evoked contractile activity of the circular and longitudinal smooth muscles were determined in each sample with a...
Albrecht BA, MacLeod JN, Daels PF.In pregnant mares, eCG stimulates luteal androgen and estrogen production, increasing plasma concentrations 2- to 3-fold. To study how these changes are regulated, we examined the expression of mRNA for the steroidogenic enzymes 3 beta-hydroxysteroid dehydrogenase (3 beta-HSD), cytochrome P450 17 alpha-hydroxylase/17,20-lyase (P450 17 alpha), and cytochrome P450 aromatase (P450arom) in equine primary corpora lutea using Northern blot analyses. Three equine specific cDNAs were generated by reverse transcriptase polymerase chain reaction. When compared to human, bovine, and rat sequences, the nu...
Ekfalck A.A method was developed for separating different layers of the matrix of the equine hoof wall by dissection, and the layers were then analyzed with respect to their amino acid composition. The results were used to compare the biochemistry of hard keratinization (e.g., in the hoof wall matrix) and soft keratinization (e.g., in the epidermis of the skin). Hard keratinization differed from soft keratinization not only by its previously well known high incorporation of cystine, but also by considerable incorporation of tyrosine and threonine into the outer layers of the keratogenous zone and by the...
Mueller PO, Allen D.Recent advances in abdominal surgical techniques in the horse have resulted in improved survival rates and reduced postoperative morbidity. The development of abdominal surgical procedures in horses has paralleled the development of safe anesthetic protocols and innovative technological advancements in humans. Irrespective of the species, the application of sound surgical principles is still the foundation of surgical intervention. This article describes recent advances in equine gastrointestinal surgical techniques. The availability and application of innovative intestinal surgical devices an...
Amri H, Silberzahn P, al-Timimi I, Gaillard JL.This present study was undertaken to clarify estrogen synthesis in the mare ovary. First of all, an evaluation of endogenous steroid contents was carried out in the follicular fluid and in the luteal tissue at different stages of the luteal phase. Radioimmunoassays were performed after separation and purification of each hormone by chromatography. High amounts of conjugated (0.9 mg/l) and unconjugated (4 mg/l) estradiol-17 beta were found in the follicular fluid of the large follicules (50 mm). These concentrations of estrogens decreased drastically in the luteal tissue, and only low levels of...
de Souza AF, Paretsis NF, De Zoppa ALDV.A systematic review was conducted to investigate evidence to support or refute the use of hyaluronic acid and polyacrylamide hydrogel as intra-articular therapy in equines, which are frequent treatment options in the routine of veterinarians of equines in cases of osteoarthritis. In total, 19 studies were included, among clinical and in vitro studies, as well as a retrospective series of cases. The outcomes of the included studies provided fragile evidence supporting the recommendation for intra-articular use of hyaluronic acid. No study was included showing any clinical outcome in diseased s...
Douwes RA, van der Kolk JH.The use of dimethyl sulphoxide in equine medicine is discussed with special reference to trauma of the central nervous system, chronic endometritis, trauma of the locomotor apparatus, and ischaemic bowel pathophysiology. The ability of dimethyl sulphoxide to reduce connective tissue formation might be of interest in abdominal surgery. The anti-inflammatory effect of dimethyl sulphoxide is used in the treatment of muscle trauma, tendinitis, laminitis, and arthritis. Dimethyl sulphoxide can potentiate the effects of other drugs. The most common dose is 1 g/kg body weight intravenously up to a 40...
Craig TM, Kunde JM.Ivermectin was injected IM into 12 yearling Shetland ponies. The following reactions in percentages of parasites recovered from ponies given 200 microgram/kg or 300 microgram/kg, as compared with the parasitic population in those given the vehicle at 1 week after injection, were as follows: Otobius megnini nymphs--no reduction; Gasterophilus intestinalis--100% and 99.9%; G nasalis--100% and 99.9%; Parascaris equorum adults--100% and 96%; Strongylus vulgaris adults--100% and 100%; S edentatus adults--100% and 100%; cyathostome adults of the genera Gyalocephalus, Cylicocyclus, Cyathostomum, Cyli...
Vanderwall DK, Squires EL, Brinsko SP, McCue PM.To determine the incidence, ultrasonographic characteristics, and risk factors associated with embryonic development characterized by formation of an embryonic vesicle without an embryo in mares. Methods: Prevalence survey. Methods: 159 pregnant mares. Methods: From 1994 to 1998, mares between 11 and 40 days after ovulation with normal and abnormal embryonic development were examined ultrasonographically, and characteristics of each conceptus were recorded. Results: The incidence of abnormal embryonic development in mares characterized by formation of an embryonic vesicle without an embryo was...
McGrath CJ.Respiratory minute volume, blood volume, RBC mass and cardiac output increase while the functional residual capacity decreases during late pregnancy. General anesthetics reach the fetus in high concentrations and tend to persist in the fetus after delivery. Use of small doses of a combination of anesthetics is recommended. Ephedrine increases vascular tone and cardiac output. Glycopyrrolate and fentanyl-droperidol are used to restrain sows for cesarean section. Morphine alone or with acepromazine works well in depressed sows. Acepromazine or xylazine, used with ketamine, is good in restraining...
Freeman DE.Guttural pouch diseases pose serious challenges in diagnosis and treatment. Complications from treatment are common and often life-threatening, largely because the unique anatomy of the guttural pouches brings them into intimate contact with the nervous, respiratory, and cardiovascular systems. There is little forgiveness for surgical errors, and so the surgeon should focus on ways to anticipate and prevent them. As with any disease, errors in diagnosis can set the stage for many surgical errors and must be recognized. This article deals with errors that can be expected after the most common s...
Palmisano M, Javsicas L, McNaughten J, Gamsjäger L, Renaud DL, Gomez DE.Anecdotal evidence suggests plasma transfusions increase serum amyloid A (SAA) concentrations in healthy neonatal foals making this marker of inflammation inappropriate for therapeutic decision making in such animals. Objective: Administration of hyperimmune fresh frozen plasma (FFP) increases SAA concentration in healthy foals and in foals with failure of transfer of passive immunity (FTPI). Methods: Eighty-six healthy foals. Methods: Prospective cohort study. Foals <24 hours of age receiving plasma transfusion for treatment of FTPI (serum immunoglobulin G [IgG] concentrations 8 g/L; nÂ...
Moraes BSS, Curcio BR, Müller V, Bruhn FRP, Santos IPOD, Danielski JNS, Nogueira CEW.The aim of this study was (i) to evaluate the relationship of climatic factors with gestational length (GL) and (ii) to evaluate the relationship of sire, foal gender and maternal factors with GL in mares. Retrospective data from 470 gestations of 202 respective mares were collected from a Criollo breeding farm in the southern hemisphere. GL was considered as the interval between ovulation and parturition. Climatic and environmental data (temperature, relative humidity, daily sunshine hours, precipitation, temperature humidity index - THI) were obtained daily and the mean values for foaling mo...
Molleda JM, Cervantes I, Galán A, Tardón R, Gallardo JM, MartÃn-Suárez EM.To describe the protocol and appearance of fluorescein angiography (FA) in normal horses. Methods: A total of 25 healthy horses aged between 5 and 15 years. Methods: The horses were sedated with 15 microg/kg detomidine and 50 microg/kg butorphanol and dilated with topical tropicamide 1%. All angiograms were recorded after intravenous bolus injection of 10 mg/kg of fluorescein sodium solution. Results: Two successive angiographic phases could be discerned: the choriopapillary phase, starting at 46.95 +/- 9.48 s, and the retinal vascular phase, starting at 47.79 +/- 10.38 s. The retinal vascular...
Machida N, Yasuda J, Too K.A morphometric study of hearts in 81 equine foetuses, ranging in age from 190 to 330 days of foetal age, and in 26 newborn foals is reported. The mean weight, external dimensions, ventricular wall thickness and circumference of the atrio-ventricular orifice were measured. Features of the main associated vessels of the heart were also recorded. All cardiac measurements of foetuses increased linearly throughout the latter half of pregnancy and were highly correlated with foetal age. This linear growth pattern was also found in the parameters of the associated arterial trunks. The ratio of the ri...
Gradil CM, Uricchio CK, Schwarz A.The present study evaluated a novel intrauterine device for its effect on estrus suppression. The self-assembling intrauterine device (Upod) consists of three 12 mm × 26 mm elliptically shaped units each with a magnetic core and coated with a polymer (total weight 22.5 g). Each magnetic unit is inserted independently from the other. Once inside the uterus, these magnetic elliptical units self-assemble and adapt the lower energy "ring" conformation. In mares, the devices can be inserted at any stage of the estrous cycle without the need for multiple exams. Shatter-proof grade material is u...
Turner JE, Irvine CH.Gonadotrophin-releasing hormone (GnRH) was used in several regimens in anoestrous mares in an attempt to investigate the effects of frequency and dose on follicle-stimulating hormone (FSH) and luteinizing hormone (LH) release, and consequently on ovulation and corpus luteum establishment. Thrice daily injections of GnRH induced development of pre-ovulatory follicles, but hourly injections or constant infusions were required to induce ovulation. Hourly injections induced a much higher LH:FSH ratio in the presence or absence of ovarian hormones. When anoestrous mares were given an implant that r...