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.
Flynn C, Forster HV, Pan LG, Bisgard GE.The objective of this study was to determine the role of hilar nerve (lung vagal) afferents in the hyperpnea of exercise. Ten ponies were studied before and 2-4 wk and 3-12 mo after sectioning only the hilar branches of the vagus nerves (HND). After HND, lung volume feedback to the medullary centers was attenuated as indicated in the anesthetized state by 1) attenuation or absence of the Hering-Breuer inflation reflex (P less than 0.01) and 2) attenuation of the lengthened inspiratory time (TI) when the airway was occluded at end expiration (P less than 0.01). Moreover, after HND in the awake ...
Dewes HF, Lowe MD.Events leading to the deaths of two fillies at pasture are described. Pasture hay containing the flowering stages of Senecio jacobea (ragwort) had been fed three to four months earlier. Paddocks were subdivided with posts and rails treated with copper chrome arsenate. Six horses on the property chewed rails spasmodically. Both fillies presented with haemoglobinurea. Values in liver of 83 mg Cu kg and kidney 35 mg Cu kg wet weight and serum 1.4 mg Cu/l together with histophathology of seneciosis support a sequence of ragwort poisoning followed by copper accumulation in liver and kidney terminat...
Steffey EP, Kelly AB, Farver TB, Woliner MJ.Circulatory and respiratory effects of intravenously administered acetylpromazine (0.033 and 0.067 mg/kg) and xylazine (0.5 and 1.0 mg/kg) were studied in drug cross-over fashion in eight laterally recumbent horses anesthetized only with halothane (1.06%, end-tidal) in O2. Both doses of acetylpromazine caused a significant and sustained elevation in cardiac output via a rise in stroke volume. Xylazine produced an initial significant fall in cardiac output followed by a return to control levels. Halothane anesthesia did not prevent xylazine-related atrioventricular conduction block. All treatme...
Martin GS, McIlwraith CW.Arthroscopic anatomy of the equine intercarpal and radiocarpal joints was documented in six cadaver limbs and on observations made during surgical treatment of horses with carpal osteochondral fractures. Instrument positions and arthroscopic visualisation were recorded. The cadaver limbs were dissected and iatrogenic lesions recorded. A single arthroscopic portal examination was adequate in both joints; however, a second arthroscopic portal improved visualisation. The intercarpal joint was more easily examined than the radiocarpal joint because of anatomical differences. Iatrogenic lesions wer...
Edington N, Bridges CG, Huckle A.Eight ponies were experimentally infected with equid herpesvirus 1 (EHV 1) (subtype 1). All animals showed clinical and serological evidence of infection and virus was isolated from nasal swabs and leucocytes. These ponies were kept in isolation for a further three months during which time complement fixing antibody decreased at least four-fold. Following immunosuppression with dexamethasone and prednisolone subtype 1 virus was recovered from six of the eight animals within 14 days. Five of these six ponies were viraemic and three of them shed virus in nasal secretions; only four displayed sig...
Crandell RA, Davis ER.The virus causing equine coital exanthema (equine herpesvirus 3) was isolated from a lesion on the nostril of a 2-month-old foal. One week after the mare had returned from a stallion station, vesicular lesions developed on her vulva. They were diagnosed clinically as coital exanthema, and 5 days later a lesion developed on the nostril of her foal. This case is an example of horse-to-horse transmission of coital exanthema virus without coitus. A laboratory diagnosis is necessary to differentiate viruses that cause vesicular lesions about the oral and nasal cavities of horses.
Haddad NS, Pedersoli WM, Ravis WR, Fazeli MH, Carson RL.Healthy mature pony mares (n = 6) were given a single dose of gentamicin (5 mg/kg of body weight) IV or IM 8 days apart. Venous blood samples were collected at 0, 5, 10, 20, 30, and 45 minutes and at 1, 1.5, 2, 2.5, 3, 4, 6, 8, 10, 12, 18, 24, 30, 36, 40, and 48 hours after IV injection of gentamicin, and at 10, 20, 30, and 45 minutes and at 1, 1.5, 2, 2.5, 3, 4, 6, 8, 10, 12, 18, 24, and 30 hours after IM injection of gentamicin. Gentamicin serum concentration was determined by a liquid-phase radioimmunoassay. The combined data of IV and IM treatments were analyzed by a nonlinear least-square...
Jann HW, Cook WR.Monopolar electrosurgical cutting was used to correct epiglottal entrapment in 5 horses. The operations were carried out in the conscious animal, using topical anesthesia. The procedure required the use of a coagulation electrode designed specifically for electrosurgery, introduced through the instrument channel of a fiberoptic endoscope. The results were satisfactory and serious complications were not encountered. In 2 horses, excessive submucosal swelling developed at the site of the surgical wound, and the tumefaction took several weeks to subside in one of these horses. In both horses, the...
Ekfalck A, Funkquist B, Jones B, Obel N.An in vitro method has been designed and used to study the incorporation of 75Se-cystine into matrix fragments from hooves and claws of healthy horses and cattle. Tissue fragments from the zone of keratinisation were incubated with L-75Se-cystine in a tissue culture medium for 4 to 6 h, during which time there was continuous incorporation of the labelled selenocystine. The incorporation was greatly decreased by adding L-cystine to the incubation mixture. It is concluded that the incorporation of 75Se-cystine depends on the presence of a specific receptor for cystine in the tissue fragments stu...
Kvart C, Carlsten J, Jeffcott LB, Nilsfors L.M-mode echocardiography is a safe and practical means of using ultrasound to evaluate the dynamic movements of cardiac structures. The technique can be refined by using a simple contrast medium in the form of carbon dioxide mixed with heparinised blood to provide a strong echogenic result. This technique was employed in a series of 15 normal conscious standing horses and in three animals with specific cardiac defects. In the clinical cases it was possible to confirm the diagnosis and differentiate between a congenital septal defect and mitral regurgitation. The method was found to be safe and ...
Errecalde JO, Button C, Mülders MS.A single intravenous administration of theophylline as aminophylline at 10 mg/kg to four mares induced a diuresis in which maximal urine production was more than seven times the control volume. The diuretic effect was maximal within the first hour post-administration, and lasted approximately 6 h. Theophylline resulted in dose-related tachycardia, polypnoea and nervous symptoms (tactile, visual and auditory hypersensitivity, muscle tremor, sweating) in normal mares, but had only minor effects on arterial and central venous blood pressures, intrapleural pressure, red blood cell variables and pl...
Nouws JF, Vree TB, Baakman M, Driessens F, Smulders A, Holtkamp J.The plasma disposition of sulfadimidine (SDM) and its metabolites N4-acetylsulfadimidine (N4-SDM), 6-hydroxymethyl-4-methyl-pyrimidine (SCH2OH) and 5-hydroxy-4,6-dimethyl-pyrimidine (SOH), was studied in three horses following intravenous administration of SDM at dose levels of 20 and 200 mg/kg in cross-over trials. The percentages of N4-SDM (0.58-0.90%), SOH (0.83-6.75%) and SCH2OH (0.38-0.71%) in plasma, expressed as a percentage of the total sulfonamide concentration, were small and their plasma concentrations were parallel with SDM from 4 h following administration. At high doses (200 mg/k...
Beech J, Irby N.Congenital cataracts affecting the fetal and embryonal lens nucleus were found in 12 Morgan horses. Ten of the 12 affected animals were sired by the same stallion and the condition also affected his female half sibling. Although females were almost three times more likely to be affected than males (9 vs 3), the difference was not significant. The ratio of 11 normal to 10 affected offspring by the affected stallion is compatible with an autosomal dominant mode of inheritance.
Honnas CM, Schumacher J.Primary gastric impaction developed in a pony as a result of the ingestion of persimmon seeds and mesquite beans. Clinical signs included mild abdominal pain, prolonged recumbency, anorexia, and lethargy. When medical therapy was unsuccessful, an exploratory laparotomy was performed. Previously, gastric impaction has been associated with signs of severe abdominal pain. Gastric impaction should be considered in cases of abdominal crisis of long duration and mild pain.
Cho DY, Hubbard RM, McCoy DJ, Stewart TB.A well-circumscribed proliferative mass was protruding from the body of the mandible of a 4-year-old Appaloosa gelding. The mass was uniformly firm and was ulcerated on the dorsal surface. The horse was euthanatized due to extensive involvement of the jaw and difficulty in eating. Microscopically, the mass consisted of numerous discrete microgranulomas separated by bands of abundant fibrous connective tissue containing lymphocytes, plasma cells, and histiocytic macrophages. Numerous rhabditiform nematodes were in the microgranulomas as well as in the surrounding connective tissue. The nematode...
Riedesel DH, Hildebrand SV.A syndrome similar to malignant hyperthermia developed in a 545-kg Quarter Horse while anesthetized with halothane for cataract removal. Succinylcholine administration caused prolonged, severe muscle fasciculations followed by tachycardia, and an elevated blood pressure. Later, while the horse was still under anesthesia, its body temperature rose 2 degrees C, and respiratory acidosis developed. Myositis developed after surgery, but the horse recovered.
Cheung AT, Liu IK, Walsh EM, Miller ME.The host defense competence of uterine-derived polymorphonuclear leukocytes (PMN) from mares considered resistant (grade I uteri) and susceptible (grade III uteri) to chronic endometritis was evaluated for phagocytic and killing (bactericidal) capacities, using a fluorochrome assay. Peripheral blood PMN from noncategorized mares and from grade I and grade III mares were used as controls. Uterine-derived PMN from mares with grade I uteri were functionally competent for phagocytosis and killing of Candida albicans, whereas uterine-derived PMN from mares with grade III uteri had significantly les...
Denny JE.Weekly blood serum samples from 20 yearling horses, divided into equal groups, receiving diets with total calcium to inorganic phosphorus ratios of 1,5/1 and 0,2/1, were analysed for calcium and phosphorus concentrations. This was done over a continuous 23 week period, divided into 2 sub-periods of 16 and 7 weeks each. During the first period complete diets were provided ad lib but were restricted during the second period to accentuate any effects of calcium deficiency and phosphorus excess. Falling calcium levels and rising phosphorus levels during period 1 and a reverse trend during period 2...
Sandstedt K, Engvall A.Sera from 116 and 89 Swedish pigs and horses respectively were examined for the presence of antibodies to L. bratislava. Antibodies were found in 18.1 and 49.4% respectively of pigs and horses examined. Presence of serum antibodies was not associated with clinical signs of infection.
Eckersall PD, Aitchison T, Colquhoun KM.Whole saliva was collected from six horses over a period of five weeks in sufficient volume for the analysis of 10 constituents. There was considerable variation in the concentration of the analytes both between horses and between different days in the same horse. The most variable constituent was sodium, and the least variable was glucose, but this was derived from the sweet used to stimulate salivation. The use of whole saliva as a fluid for investigation would depend on achieving the minimum variability possible.
Schamhardt HC, Hartman W, Lammertink JL.The present study was undertaken to determine the influence of the peroneus tertius muscle on the loading regime of the tibia in the horse. Strain gauge rosettes were bonded to the cranial and caudal cortices of the left and right tibiae in six Shetland ponies. In vivo bone strain recordings were made before and after unilateral transection of the peroneus tertius muscle. Relatively large individual variations in response to transection were observed in both the experimental and the contralateral control limbs. The principal strain values on the cranial and caudal cortices increased during the...
Rikihisa Y, Perry BD.An ehrlichia was consistently isolated from the peripheral blood leukocyte fraction of ponies that had been experimentally infected with Potomac horse fever by whole blood transfusion from naturally infected horses. The organism was propagated in a human histiocyte cell line for 3 to 5 weeks and then inoculated intravenously or intradermally into healthy adult ponies. Clinical signs of Potomac horse fever, which varied in the degree of severity, occurred 9 to 14 days post-inoculation in all of the ponies. One pony died 20 days post-inoculation. The ehrlichial organism was reisolated in the hum...
Kelly AB, Steffey EP, McNeal D, Willits N.The acute and long-term quantitative and qualitative effects of halothane anesthesia on equine platelet performance were studied in fourteen horses. Horses were anesthetized with only halothane in O2 for about 8.0 MAC hours. Platelet numbers declined during the anesthetic period but returned to normal within 24 h. Platelet aggregation was significantly diminished during the anesthetic period and for up to 4 days after anesthesia. A period of hyperaggregability occurred at the 7th day.
Wilson WD, Baggot JD, Adamson PJ, Hirsh DC, Hietala SK.Sodium cefadroxil was administered as a single intravenous dose (25 mg/kg) to six healthy adult mares. Plasma samples were collected over a 24-h period and cefadroxil concentrations were measured by microbiological assay. The pharmacokinetic behavior of the drug was appropriately described in terms of a one-compartment open model. Values for the major pharmacokinetic terms were: extrapolated initial plasma concentration = 59.2 +/- 15.0 micrograms/ml; half-life = 46 +/- 20 min; apparent volume of distribution = 462 +/- 191 ml/kg; and body clearance = 7.0 +/- 0.6 ml/min.kg. In a subsequent study...
Muir WW.The haemodynamic effects of milrinone hydrochloride were determined in halothane-anaesthetised horses. Six healthy adult horses were anaesthetised with guaifenesin and thiamylal and maintained with halothane in oxygen (end-tidal halothane concentration of 1.15%). Baseline haemodynamic data were recorded after a 45 min stabilisation period. All 6 horses received a single loading dose of milrinone HCl, 0.2 microgram/kg i.v., followed by progressively increasing infusions of 2.5, 5, 10 and 20 micrograms/kg bwt/min. Each infusion lasted for 15 min and produced dose related increases in heart rate,...
Ginther OJ, Williams D, Curran S.Transrectal ultrasonic examinations were made in 31 pregnant pony mares once a week during Months 6 to 11. Each uterine horn was divided into 3 approximately equal segments (caudal, middle, cranial). The percentage of examinations with cranial fetal presentation increased (P<0.05) progressively from 58% at Month 6 to 99% at Month 9 and was followed in all mares by entry of the fetal hind limbs into one uterine horn. The mean number of uterinehorn segments with limb parts increased (P<0.05) between each set of consecutive months from Month 6 to Month 10. Initially (Months 7 and 8), retrac...
Kareche H, Daly JM, Laabassi F.Equine influenza (EI) is one of the most contagious respiratory infections in horses, donkeys and mules, caused by equine influenza A virus (EIV). It remains a disease with a strong economic stake for the equine industry. This review focuses on the epidemiological situation of EIV in the Maghreb area, which includes Algeria, Morocco and Tunisia. There is serological evidence for extensive circulation of EIV in the Maghreb area since the early 1970s, but reports of detailed investigation of outbreaks are scarce with no documented isolation or molecular characterization of EIV from Tunisia. Isol...
Manning HS, Runcan EE, Dias de Moraes CR, Coutinho da Silva MA.The objective of this study was to use estrous behavior alone to determine the appropriate time for beginning an oxytocin treatment protocol for estrus suppression. We hypothesized that administration of oxytocin beginning 8 days after the onset of estrus will prolong the luteal phase in mares. Twenty-three light breed mares (aged 4-20 years) were exposed to a stallion and observed for signs of sexual receptivity. Mares not displaying signs received 250 μg of cloprostenol intramuscularly (IM) and were teased again 3-4 days later. On the day that estrous behavior was observed (Day 0), mare...
Dinev D, Andonova M.To compare the effect of anesthesia alone with anesthesia and abdominal surgery on plasma thromboxane B(2) concentrations in horses. Methods: Non-randomized experimental study. Methods: Six male mixed-bred horses (5-12 years, 350 +/- 18 kg). Methods: All horses were anesthetized for 2.5 hours using halothane, and a month later abdominal surgery was performed using the same anesthetic technique with a similar duration. The schedule of anesthesia included pre-medication with diazepam (0.1 mg kg(-1) IM), followed by xylazine (2.2 mg kg(-1) IV), and 10 minutes later anesthesia was induced with ket...
Rick MC.Diagnosis, evaluation, and management of the various grades of rectal tears is discussed. Surgical techniques, which include direct closure, diverting colostomies, and placement of temporary rectal liners, are detailed. Also, rectal prolapses and various methods of repair are outlined.
White SD, Bourdeau P.Hereditary equine regional dermal asthenia (HERDA) in Quarter Horses is an inherited degenerative skin disease. Initially reported as hyperelastosis cutis, HERDA has a phenotype of hyperextensible, fragile skin, with secondary seromas, haematomas, ulcers and scarring. It primarily affects the dorsal aspect of the body. An autosomal recessive mode of inheritance is considered likely, with affected horses more at risk to produce affected offspring. A mutation in cyclophilin B (PPIB) as a novel, causal candidate gene for HERDA has been described, and verified as segregating with carriers and affe...
Montavon S.Few scientists predicted the impact that echography would have on the equine breeding industry. The aim of this practical review is to give the practitioner the ability to be familiar with the ovarian echographic exam. He should be able to recognize different stages of estrous cycle in the mare, status of preovulatory follicles and to predict precisely the time of ovulation. Various specific criteria and details regarding the equine echography are studied and illustrated, using the last scientific data published after the Fifth International Symposium on Equine Reproduction in Deauville.
Stadler P, Van Amstel SR.Commercially available Escherichia coli 055: B5 lipopolysaccharide was administered intravenously experimentally at a dosage of 10 micrograms/kg to 2 horses. Various clinical and clinico-pathological parameters were monitored before and after the endotoxin administration. Because of a hopeless prognosis, and for humane reasons, euthanasia was applied on both horses 6 h after administration. Values recorded for the different parameters, including the blood lactate level, were consistent with a lethal condition. It would appear that an intravenous dose of 10 micrograms/kg of endotoxin is potenti...
Hassanpour A, Moghaddam S.Early detection of Rhodococcus equi pneumonia in foals is essential for horse health and for veterinarians. Objective: This study aimed to demonstrate the usefulness of assessing the serum concentration of acute-phase proteins (APPs) in the early diagnosis of pneumonia. Methods: The study evaluated APPs in 19 Arabian foals with R. equi pneumonia and compared them with 18 normal Arabian foals in equestrian clubs in Tabriz, Iran. Affected foals were identified through history, clinical findings and bacterial culture of tracheal washing. Biochemical methods and polymerase chain reaction tests wer...
Otto P, Elschner M, Schulze P, Prudlo J, Schrader R.The commercially available immunoassay "OnSite Rotavirus" was used for the detection of animal rotaviruses in 113 faecal samples. The sensitivity of the test was 88% and the specificity 96% compared with reference methods (EIA, EM). This test would detect approximately 4.4 x 10(6) to 1.8 x 10(7) virus particles per ml. The presence of virus could be demonstrated in fresh faecal samples from cattle, horses and pigs within a few minutes. The rotaviruses of group A were identified independently of the virus serotype. Further results and additional problems of using this test kit are described.
Hasslinger MA, el-Seify MA.The investigation of 156 donkeys in the area of the veterinary faculty of the Tanta University in Kafr el-Sheikh showed that 49 animals (31.41%) were infected with trematodes, 34 donkeys (21.80%) served as hosts for Gastrodiscus aegyptiacus, 22 (14.10%) were infected with Fasciola gigantica und 7 (4.49%) with both trematodes. 6 of 40 examined horses (15.0%) showed monoinfections with G. aegyptiacus only. Because of the fragmentary knowledge on these paramphistomides of equids, some aspects concerning the morphology, pathology and clinical symptoms, differential diagnosis, occurrence, host spec...
Braganti G.In 1916 Louis Desliens, veterinary practitioner; submitted to the Academy of Sciences a description of a new way of exploring the cardiovascular system: percutaneous catheteri- zation. In 1935 he published the results of thirty years of explorations in hemodynamics mainly in horses: physiology, pathophysiology and pharmacodynamics. The text considers the very pioneering nature of these studies.
Zaruby JF, Livesey MA, Percy DH.This clinical report describes an 8-year-old Thoroughbred mare that was presented for evaluation of a chronic, unilateral nasal discharge. Findings on physical examination, radiology, and video-endoscopy supported a clinical diagnosis of ethmoidal hematoma. After surgical ablation of the mass a defect was detected in the cribriform plate. At necropsy a 1.5 cm aperture was identified in the left cribriform plate allowing direct communication between the fundus of the nasal cavity and the cranium. Histology of the mass identified tissue consistent with an adenocarcinoma. History of profuse epist...
Grabner A, Goldberg M.In a blind study serum and cerebrospinal fluid (CSF) of control horses and of horses in hepatic coma after chronic food intoxication with Senecio alpinus were collected simultaneously and the composition of free amino acids was determined. The hepatic encephalopathy index in serum (less than 1.65) and in CSF (less than 1.11) of liver patients was distinctly less than to the control values in serum (greater than 2.42) and in CSF (greater than 1.49). The serum concentrations of glutamic acid in hepatic coma were elevated five-fold in comparison to the controls. An indication of ammonia decontami...
Woodger K, Stone EA.This article seeks to examine the history of equine surgery at the Ontario Veterinary College (OVC) in the context of the changing horse economy during the first half of the 20th century. We argue that despite the transition to livestock medicine, public health and small animal practice, the horse, especially as a surgical topic, retained a (diminished) place at OVC due to the lucrative new recreational equine market, the deep links between horses and veterinary medicine, and the equine focus for nearly half a century of Dr. W.J.R. Fowler, the College's primary surgical instructor.