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.
Blythe LL.Methodology for the neurologic examination in the equine species is described. Information is organized to assist the reader in defining neurologic deficits and in localizing lesions to the major subdivisions within the central or peripheral nervous system. Numerous examples of deficits are presented to assist the reader in recognition of common neurologic disease states.
Skalka B.The occurrence of equi-factor antibodies in sera of mares and their foals was studied on two horse breeding farms, one of which (Farm A) had a positive and the other (farm B) a negative history of R. equi infection of foals. The equi-factor neutralization (EFN) and the reverse Elek-Ouchterlony (REO) precipitation were used as assays. On Farm A, 25 mares positive in both tests (EFN+ REO+) and 25 mares negative in both tests (EFN- REO-) was chosen. On Farm B, a group of 25 EFN- REO+ mares and a group of 25 EFN- REO- mares were studied. The first serum samplings in mares were 1 week ante partum a...
Woolcock JB, Mutimer MD, Bowles PM.Normal horses of all ages regularly show evidence of having responded immunologically to R. equi, thus adding serological support to epidemiological evidence that this organism is a normal intestinal inhabitant. More animals from "diseased" farms show a stronger antibody response when compared with foals from "healthy" farms. Various serological tests have been used to detect evidence of infection and to relate antibody level to severity of disease. Anti-R. equi IgG antibody levels, as measured by ELISA, are raised significantly during natural infection. Clinical severity of pneumonia can be c...
Barragry TB.The avermectins were introduced in 1981 and constitute a potent new class of anthelmintic agents. They are naturally-derived products of microbial action displaying an exceptionally wide range of antiparasitic efficacy against internal and external parasites of domestic animals. This paper reviews their isolation and chemistry, mechanism of action, chemical efficacy and safety in cattle, sheep, swine, horses and dogs.
Watrous BJ.Head tilt in the horse is commonly a sign of either central or peripheral vestibular disease. The confirmation of vestibular disease is based on physical findings, including results of cranial-nerve function evaluation and observation of stance, posture, and gait. Further localization is made by ancillary tests such as cerebral spinal fluid analysis, electrodiagnostic testing, and radiography. The normal anatomy and physiology of the vestibular system, the abnormal clinical signs demonstrated during physical examination, and the various etiologies are discussed.
Richardson DW, Nunamaker DM, Sigafoos RD.Arthrodesis of the metacarpophalangeal joint was attempted in 9 adult horses, using a new external skeletal fixation device and autogenous cancellous bone graft. Four horses had excellent results, 2 horses had fair results, arthrodesis failed in 2 horses, and 1 horse fractured the third metacarpal bone. The advantages of the technique included minimal surgical trauma to the area of injury, immediate rigid fixation of the metacarpophalangeal joint, and access for treatment of soft-tissue lesions at the site of injury. Although pin loosening and pin-track infection were complications when the de...
Stewart RH, Griffiths JP.In spinal cord disease of horses, a complete history, neurologic examination, and adjunctive diagnostic procedures are very helpful in establishing a tentative diagnosis; however, a definitive diagnosis may be difficult or impossible to establish antemortem. Medical management should be initiated with full consideration of possible etiologies and knowledge of the effects and consequences of medical therapies. This article discusses the drugs commonly used in the management of spinal cord disease and the rationale for their use.
MacLachlan NJ.The histologic appearance of the ovaries and persistence of corpora lutea vary considerably among domestic animals, particularly between spontaneous and induced ovulators. The seasonally polyestrous mare has a variety of unique characteristics in ovarian structure and general reproductive function. Among the anomalies of ovarian development is the bovine freemartin with gonads containing a mixture of male and female elements. A variety of ovarian cysts occur in domestic animals, and persistent corpora lutea with associated reproductive perturbations occur in several species. Ovarian tumors are...
King WA, Bezard J, Bousquet D, Palmer E, Betteridge KJ.Confusion exists as to whether the oocytes of the domestic horse are ovulated at the first meiotic metaphase (MI) or the second (MII). In this study eight oocytes were collected from the preovulatory follicles of 16 mares 36 h after human chorionic gonadotropin CG treatment. Six of the eight oocytes were judged to be at MII by the presence of the first polar body and this judgement was confirmed by semithin sectioning in one. Of the two that had no polar body, one was found to be at MII after fixation for chromosomal analysis and the meiotic stage of the other remained undetermined. Since all ...
Morris DD, Bruce J, Gaulin G, Whitlock RH.Granulocyte transfusions (GT), 0.98 X 10(9) neutrophils/kg of body weight, were performed on 7 healthy pony foals between 2 and 7 days old. The mean neutrophil count of the foals was significantly (P less than 0.05) greater than base line (4,830 +/- 1,260/microliter) 1 hour after GT (8,870 +/- 3,350/microliter) and was similar to base line by 15 to 18 hours after GT (6,550 +/- 2,310/microliter). Leukocyte concentrates (LC) used for GT were harvested from clinically normal adult horses by continuous-flow centrifugation leukapheresis (CL), 3 to 6 hours after hydrocortisone sodium succinate was a...
Martens RJ, Martens JG, Renshaw HW, Hietala SK.The opsonic capacity of serum containing R. equi-specific antibody was compared with antibody-deficient sera using luminol-dependent chemilumenscence (LDCL) and bactericidal assays. These assays incorporated peripheral blood polymorphonuclear neutrophilic leukocytes (PMNL) exposed to R. equi opsonized with neonatal equine pre-colostral serum (control) or serum from foals with R. equi infections (principal). All sera were complement inactivated at 56 degrees C for 30 min. Bacteria were obtained from the lung of a foal with R. equi pneumonia. Neutrophils were obtained from one adult horse for LD...
Prescott JF.Current understanding of the epidemiology of Rhodococcus equi infection on horse farms is reviewed. Infection is widespread in herbivores and their environment, because herbivore manure supplies the simple organic acid substrates on which the organism thrives. There is a progressive development of infection in the soil on horse farms with prolonged use, because: (1) there is a continual supply of nutrients; (2) the organism multiplies progressively as temperatures rise; (3) the bacterium has a robust nature. While this aerobic organism fails to multiply in the largely anaerobic intestine of th...
Andrews FM, Fenner WR.Electrodiagnostic aids, electromyography, auditory brainstem response testing, and electroencephalography are extensions of the neurologic examination and provide valuable information about the nervous system. This article discusses the use and interpretation of electrodiagnostic aids in equine neurology as well as the equipment that is employed. It is hoped that with a better understanding of the available electrodiagnostic aids, they will come into greater use.
Reef VB.Mitral valvular insufficiency associated with ruptured chordae tendineae was diagnosed in 3 foals with signs of congestive heart failure, which were believed to be secondary to the development of pulmonary hypertension associated with the valvular insufficiency. The septal leaflet of the mitral valve was affected in all 3 foals, and foal 2 also had ruptured chordae tendineae associated with the caudal mitral valve leaflet. Bacterial endocarditis and myocardial necrosis were associated with the ruptured chordae tendineae in foals 3 and 2, respectively. Idiopathic rupture was considered in foal ...
Caron JP, Fretz PB, Bailey JV, Barber SM, Hurtig MB.Epistaxis, caused by guttural pouch mycosis, was treated by balloon-tipped catheter and ligature occlusion of the involved arteries in 13 horses. In 7 horses, more than one artery was catheterized. Serious postoperative hemorrhage was prevented in all horses. Long-term endoscopic follow-up examination was possible in 8 horses, and all had complete regression of the fungal lesion as early as 5 weeks after surgery. Six of the 8 horses did not receive medical treatment. Problems related to the use of the balloon-tipped catheter technique were rare. There were incisional infections in 3 horses, ca...
Yager JA.The pathogenesis of Rhodococcus equi pneumonia in foals is reviewed. The main routes of infection are respiratory and alimentary. The latter is probably the chief route of exposure in all foals and probably leads to development of specific immunity. Susceptible foals, those whose maternal immunity wanes before generation of their own immune response, readily develop disease if exposed aerogenously to sufficient numbers of R. equi. Management and environmental circumstances have a major role to play in determining the magnitude of this challenge and, therefore, in the prevalence of the disease....
Takai S, Fujimori T, Katsuzaki K, Tsubaki S.Quantitative culture of R. equi in the feces of dams and foals, in the air of the stalls and in the soil of the paddocks was carried out on three horse-breeding farms during the foaling season. The isolation rates of R. equi from the feces of dams from the 3 farms suddenly increased to approximately 80% at the end of March, when the snow in the paddocks finished melting, and remained at that level during April and May. The mean number of R. equi and the isolation rate of R. equi from the feces of dams on the farms were investigated for 5 weeks before and 5 weeks after delivery. During the 10 w...
Wagner PC, Grant BD, Reed SM.Cervical vertebral malformations are recognized clinically when they result in spinal cord compression causing neurologic deficits. Confirmation of diagnosis is based on radiographic and myelographic evidence of cord compression. Medical therapy is not usually successful. Several successful surgical treatments are described.
Keane DP, Little PB.Rabies, equine herpesvirus type I, and eastern and western encephalomyelitis viruses, known causes of equine neurological disease, are reviewed with emphasis on epidemiology, pathogenesis, clinical signs, and diagnosis.Several arboviruses known to be active in Canada and capable of producing neurological disease in humans (Powassan, St. Louis encephalitis, snowshoe hare, and Jamestown Canyon viruses) are discussed as potential causes of encephalomyelitis in horses.
Yager JA, Duder CK, Prescott JF, Zink MC.Polymorphonuclear neutrophil leukocytes (PMNL) from 8 healthy foals (2-14 weeks of age) and 2 foals with bacterial pneumonia were separated from whole blood using a 2 step Percoll gradient. Purified PMNL were tested for bactericidal function against Rhodococcus equi and Staphylococcus aureus in the presence of normal horse serum. The percentage uptake after a 15-min pre-incubation of PMNL and bacteria was also calculated. Ultrastructural examination of the interaction of R. equi and normal foal PMNL was performed after 15 min incubation. Results indicated that foal PMNL effectively phagocytose...
Hayes TE.The examination of cerebrospinal fluid (CSF) is often part of the diagnostic work-up of a patient exhibiting signs of disease involving the central nervous system. Awareness of the capabilities and limitations of these laboratory tests is important in assessing the benefit-to-risk ratio of performing such procedures. Collection of CSF is a relatively simple procedure, and together with a thorough history, physical examination, and other diagnostic tests, may be a valuable aid in arriving at a diagnosis or prognosis.
Steffey EP, Dunlop CI, Cullen LK, Hodgson DS, Giri SN, Willits N, Woliner MJ, Jarvis KA, Smith CM, Elliott AR.Cardiovascular and respiratory changes that accompany markedly long periods (12 hours) of halothane anesthesia were characterized. Eight spontaneously breathing horses were studied while they were positioned in left lateral recumbency and anesthetized only with halothane in oxygen maintained at a constant end-tidal concentration of 1.06% (equivalent to 1.2 times the minimal alveolar concentration for horses). Results of circulatory and respiratory measurements during the first 5 hours of constant conditions were similar to those previously reported from this laboratory (ie, a time-related sign...
Bochsler PN, Slauson DO, Chandler SK, Suyemoto MM.The use of cultured tissue has not yet become widespread in research involving equine disease, and this may be attributable in part to the scarcity of published reports concerning tissue culture methods for this species. We report here the isolation of equine microvascular endothelium (EMVE) from fresh omental tissue of horses and ponies. Fresh donor tissue was minced, subjected to collagenase digestion, and filtered. Cells were layered on 5% bovine serum albumin for gravity sedimentation, the bottom layer was collected, and the cells were plated onto fibronectin-coated flasks. Medium consiste...
Chidambaram RM, Eades SC, Moore RM, Hosgood G, Venugopal CS.To characterize the in vitro response of equine cecal longitudinal smooth muscle (CLSM) to endothelin (ET)-1 and assess the role of ETA and ETB receptors in those ET-1-induced responses. Methods: 36 horses without gastrointestinal tract disease. Methods: To determine cumulative concentration-response relationships, CLSM strips were suspended in tissue baths containing graded concentrations of ET-1 (10(-9) to 10(-6)M) with or without BQ-123 (ETA receptor antagonist); with or without IRL-1038 (ETB receptor antagonist); or with both antagonists at concentrations of 10(-9), 10(-7), and 10(-5)M. To...
Whiting TL, Sauder RA.Horses intended for slaughter in Western Canada are frequently transported in double-deck trailers, where headroom may be restricted. Poll and withers height was estimated from type photographs of various horse breeds. The headroom required by Canadian legislation and codes of practice may not be sufficiently restrictive to protect the welfare of sport type horses when transported.
Clark ES, Moore JN.Lateral cecal arterial blood flow, carotid arterial pressure, heart rate, and mechanical activity of the circular and longitudinal muscle layers of the cecal body were measured in 7 conscious healthy horses during IV infusion of physiologic saline solution for 60 minutes (control), during a 60-minute IV infusion of dopamine (at dosages of 1, 2.5, and 5 micrograms/kg/min), and for 60 minutes after IV infusion of dopamine. The mean values for lateral cecal arterial blood flow during IV infusion of dopamine at a dosage of either 1 or 2.5 micrograms/kg/min were not significantly different from the...
Deanesly R.During the 340 day pregnancy of the horse, the germ cells in the fetal ovary showed a meiotic prophase which began in days 60-70 and might be prolonged after day 200. Three or four successive oogonial mitotic proliferations passed into the meiotic prophase but the great majority of the oocytes first involved degenerated, and no appreciable numbers of primordial follicles were left behind. At 150 days of pregnancy and again at 197 days, oocytes in early meiotic stages filled the ovarian cortex. Primordial follicles were present, but rare. As the prophase gradually came to an end, groups of oocy...
Pye J, Kilcoyne I, Roy M, Vaughan B, Ormond C, Spriet M.A 20-year-old Quarter horse gelding was referred for evaluation of an acute onset non-weight-bearing right forelimb lameness. Marked soft tissue swelling was apparent over the right scapula and shoulder region; no crepitus was palpable. A complete transverse fracture of the scapular neck was suspected based on ultrasonography and radiographs were obtained to confirm the presumptive diagnosis. A complete, oblique fracture of the right scapular neck with mild cranial and proximal displacement of the distal fragment was detected. Computed tomography of the upper right forelimb was performed post-...
Boswinkel M, van der Lugt JJ, Sloet van Oldruitenborgh-Oosterbaan MM.Rhodococcus equi infection occurs worldwide and is especially a problem in foals, where it often causes colitis or pneumonia. Other organs are seldom affected, and their involvement is regarded as a complication of pneumonia and/or colitis. Vertebral osteomyelitis is one such rare complication and is probably caused by haematogenous spread from inflammatory lesions in the lungs and/or intestine. In rare cases, osteomyelitis can be caused by contamination of a wound. This case study describes a foal with vertebral osteomyelitis due to R. equi in which there were only minor inflammatory changes ...
Kotzé SH.The veins draining the ileocaecal junctions of horses (n = 19), donkeys (n = 3) and a plains zebra, (Equus burchelli antiquorum) were injected with latex via the ileocolic vein, and dissected. In all specimens the ileocaecal papilla was drained by 2 major papillary veins: one cranial and one caudal to the papilla. A smaller dorsal vein drained either into the cranial or into the caudal vein. The submucosal veins seemed to increase in number in the ileocaeacal junction to form a venous plexus. This plexus, together with veins from the caecum and the distal ileum immediately bordering the ileoca...
Delbeke FT, Vynckier L, Debackere M.A high performance liquid chromatographic method is described to determine the anti-inflammatory drug suxibuzone (SXB) and its major metabolites phenylbutazone (PBZ) and oxyphenbutazone (OPBZ) in equine plasma and urine. When suxibuzone (6 mg/kg) was administered intravenously (i.v.) or orally (p.o.) no parent drug was detected in plasma or in urine. The disposition of the metabolite PBZ (i.v.) could be described by a 2 compartment model with a beta half-life varying from 7.40 to 8.35 h. Due to severe side effects the use of i.v. suxibuzone should not be encouraged in the horse. PBZ and OPBZ w...
Morsy AT, Saleh MS, Morsy TA.A zoonosis is an animal disease that is transmissible to humans. Humans are usually an accidental host that acquires disease through close contact with an infected animal, who may or may not be symptomatic. Children are at highest risk for infection because they are more likely to have close contact with pets. Pets are responsible for transmission of an extensive array of bacterial, fungal, and parasitic zoonotic pathogens. The route of transmission can be through the saliva (e.g., bites or contaminated scratches), feces, respiratory secretions, direct contact, or by the animal acting as a veh...