The study of diseases in horses encompasses a wide range of conditions affecting equine health, including infectious diseases, metabolic disorders, and genetic abnormalities. These diseases can impact various systems within the horse, such as respiratory, gastrointestinal, and musculoskeletal systems, and can lead to significant health challenges. Research in this area focuses on understanding the pathophysiology, diagnosis, prevention, and treatment of equine diseases. Common diseases studied include equine influenza, equine herpesvirus, and laminitis. This page provides access to peer-reviewed research studies and scholarly articles that explore the etiology, clinical presentation, and management strategies of diseases in horses, contributing to the advancement of equine veterinary medicine.
King TC, Priehs DR, Gum GG, Miller TR.The records of 50 horses with ocular squamous cell carcinoma (OSCC) presented to the University of Florida Veterinary Medical Teaching Hospital over an 11 year period were reviewed to determine the influence of therapy on the outcome of the case. Follow-up information was obtained for 43 of the 50 cases. The disease was more prevalent in the light horse breeds; however, the draft breeds also were at risk. There was no sex predisposition and the average age was 11.8 years. Tumour recurrence was significant when surgery alone was performed. The eyelid and nictitating membrane were the primary si...
Wilson DV, Nickels FA, Williams MA.Benztropine mesylate was used successfully to treat priapism that developed during anesthesia in 2 horses. After IV injection, there was a rapid resolution of signs in both horses, and no side effects were observed. The choice of an effective method to treat priapism is challenging because precise causes in most patients have not been well-defined. Benztropine mesylate is a synthetic compound resulting from the combination of the active portions of atropine and diphenhydramine, and is believed effective because of its central acetyl-choline-antagonizing properties.
Jaeschke G, Rudolph R.In a review supplementary to prior evaluations further hematological or cytodiagnostic aspects respectively of equine leucosis are discussed. Leukemic nature of the disease is characterized by increased count of normal blood cells or by the presence of morphologically non-differentiated cells in circulating blood or by disorder or loss of function of blood cells respectively. Thrombocytopenia in the most cases is accompanied by anemia, leukemia and tumor cell infiltration in bone marrow. Tumor cells in circulating blood indicate their presence in bone marrow too. In cases of equine leucosis wi...
Perryman LE, Bjorneby JM.Immunotherapy for persistent infection caused by Cryptosporidium parvum was attempted in two immunodeficient animal models. BALB/c Athymic (nude) mice were infected with two oral doses of 2 x 10(7) C. parvum oocysts, and subsequently treated with monoclonal antibody (MAb) 17.41 that neutralizes sporozoites and merozoites. Persistent infection was established in all exposed mice. Daily oral treatment with MAb 17.41 for 10 days significantly reduced (p less than 0.005) the number of C. parvum organisms observed by microscopic study of intestinal tracts of infected mice. Young horses with severe ...
Peel MM, Hornidge KA, Luppino M, Stacpoole AM, Weaver RE.We describe the isolation of Actinobacillus lignieresii and an A. equuli-like bacterium from an infected horse-bite wound in a 22-year-old stable foreman and A. suis from a bite injury in a 35-year-old man who had been attacked by a horse. A. lignieresii was also isolated in pure culture from an infected sheep-bite wound in a rural worker. These species of the genus Actinobacillus are primarily associated with animals and animal diseases and are rarely isolated from humans. The purpose of this report is to raise awareness of the possible occurrence of Actinobacillus spp. in bite wounds inflict...
Heinrich B.This research article corrects a common misconception about the energy metabolism in horses during short sprinting and long-distance running events, emphasizing that short sprints are primarily powered by anaerobic activity, […]
Bjorneby JM, Leach DR, Perryman LE.Cryptosporidial infections were established in five young foals with severe combined immunodeficiency following oral administration of 10(8) Cryptosporidium parvum oocysts. All foals shed oocysts (average of 8 x 10(6) to 2 x 10(8)/g of feces) until death. Inflammation and C. parvum organisms were observed in the common bile duct, duodenum, jejunum, and ileum. Since foals with severe combined immunodeficiency lack functional T and B lymphocytes and are incapable of antigen-specific immune responses, they are well suited for evaluating the pathogenesis and treatment of persistent cryptosporidios...
Nation PN.Over sixteen years, 49 horses were diagnosed by Alberta Agriculture Animal Health laboratories as having "alsike clover poisoning". There was a distinct northwestern distribution of cases, the majority coming from the Peace River district. This distribution is opposite to that of the Alberta horse population, but coincides with areas of alsike clover cultivation. Cases could be divided into chronic or nervous clinical presentations, as described by Schofield. Tissues from 45 animals were retrieved and examined microscopically. Significant histological lesions were confined to the liver and con...
Biswas B, Mukherjee D, Mattingly-Napier BL, Dutta SK.Genomic amplification by the polymerase chain reaction (PCR) was used to identify a unique genomic sequence of Ehrlichia risticii directly in DNA isolated from peripheral-blood buffy coat cells of E. risticii-infected horses (Potomac horse fever) and from infected cell cultures. A specific primer pair, selected from a cloned, species-specific, 1-kb DNA fragment of the E. risticii genome as a template, was used for the amplification of the target DNA of 247 bp. The optimal number of 40 PCR cycles, determined by analyzing an amplification profile obtained with a constant Taq polymerase concentra...
Meyer H.Colics are often initiated by mistakes in feeding inadequate feed quality or quantity or poor feeding technique. The consequences are obstruction, impaction or dysbiosis with increased production of organic acids, gas or toxins. Nutritional anamnesis in patients with colic may give information on the pathogenesis of the disease.
Heath TJ, Nikles SA.Secondary lymphoid nodules in lymph nodes of the horse are surrounded by a network of lymph sinuses, including the subcapsular sinus and its extensions around tabeculae, tubular and tubule-like sinuses deeper in the cortex, and sinuses between cord-like projections of cortical tissue. The precise role of this close association between sinuses and nodules in the transport of immune complexes, cells and cytokines is not known.
Kroneman J.The clinical importance of the AV blocks in horses discussed. The second degree AV block is a symptom of the adaptation of the heart to increased workload and it is not an indication of a good performance.
Whalley M, Robertson G, Bell C, Love D, Elphinstone M, Wiley L, Craven D.A homologue of the herpes simplex virus (HSV) glycoprotein D gene has been identified in the genome of equine herpesvirus-1 (EHV-1, equine abortion virus). An open reading frame in the middle of the short unique (US) region is capable of encoding a polypeptide of 402 amino acids that has 26% and 20% of its residues matching pseudorabies virus (PRV) gp50 and HSV-1 gD, respectively. Despite this low level of similarity, the positional identity of six cysteine residues and certain motifs, and the location of the EHV-1 gene, clearly define the EHV-1 polypeptide as one of a family of "gD-like" prot...
Kähn W, Vaala W, Palmer J.Aetiology, pathogenesis, clinical symptoms, diagnosis, prophylaxis and therapy of neonatal isoerythrolysis in foals are presented. Neonatal isoerythrolysis is caused by isoimmunisation of a brood mare to the Aa and Qa erythrocyte antigens of the foal. The disease can develop, when the mare does not possess Aa resp. Qa blood group antigens, is sensitized to the Aa or Qa erythrocyte antigens--i.e. through pregnancy, parturition, blood resp. plasma transfusions, etc.--and the foal suckles colostral antibodies to its own blood cells. Aa and Qa antibodies can cause haemagglutination and haemolysis ...
Davis SW, Speer CA, Dubey JP.Asexual stages of Sarcocystis neurona were seen in cultured bovine monocytes (M617) inoculated with tissue homogenates from the spinal cord of a horse with naturally acquired protozoal myelitis. Organisms first were observed as intracytoplasmic schizonts and later as motile extracellular zoites capable of infecting surrounding M617 cells. Parasites most often occurred as clusters of merozoites dispersed throughout the host cell cytoplasm; however, schizonts also contained merozoites arranged in a radial fashion surrounding a prominent residual body. Schizonts divided by endopolygeny. The paras...
Boersema JH, Borgsteede FH, Eysker M, Elema TE, Gaasenbeek CP, van der Burg WP.A survey to determine the prevalence of anthelmintic resistance of horse strongyles was carried out with 616 horses on 22 farms. The tested drugs were cambendazole, pyrantel pamaote and ivermectin. Based on egg count reduction tests the efficacy of cambendazole varied from 0% to 93% and of pyrantel from 93% to 100%. Ivermectin treatments were 100% effective on all farms. Larval cultures after cambendazole treatments revealed exclusively cyathostome larvae. After pyrantel treatments besides cyathostome larvae other types of larvae were also found. After ivermectin treatments only a few cyathost...
Kitamoto N, Ramig RF, Matson DO, Estes MK.The production of viral antigen after infection of MA104, HepG2 (derived from human liver), and CaCo-2 (derived from human colon) cells with various cultivatable human and animal rotavirus strains was compared using immunofluorescence tests. All rotavirus strains examined expressed antigen in CaCo-2 cells and MA104 cells, but only some virus strains, namely, SA11-Cl3 (simian), RRV (simian), CU-1 (canine), and Ty1 (turkey), produced antigen in numbers of infected HepG2 cells comparable to infections in MA104 and CaCo-2 cells. Fl-14 (equine), OSU (porcine), NCDV (bovine), and Ch2 (chicken) strai...
Kamada M, Wada R, Kumanomido T, Imagawa H, Sugiura T, Fukunaga Y.A study was performed to examine the effect of viral inoculum size on the appearance of clinical signs in equine Getah virus (GV) infection by intramuscular inoculation with 10(1.3) to 10(6.3) TCID50 of the MI-110 strain in 6 experimental horses. When inoculated with more than 10(3.3) TCID50 of the virus, every horse developed pyrexia, edema in the hind legs, serous nasal discharge, lymphopenia and viremia in the relatively early stage of disease. On the other hand, enlargement of the submandibular lymph node was observed only in horses inoculated with 10(5.3) and 10(6.3) TCID50 of the virus, ...
Cohen ND, Carter GK.Persistent thrombocytopenia was detected in a horse with equine infectious anemia (EIA). The thrombocytopenia was considered to be immune-mediated, developing secondary to infection with EIA virus. Epistaxis, petechial hemorrhages, subcutaneous hematomas, and edema resolved after treatment with corticosteroids; however, the owners requested that the mare by euthanatized because of infection with EIA virus. Although clinical signs attributable to immune-mediated thrombocytopenia may resolve with appropriate treatment, horses with immune-mediated thrombocytopenia secondary to EIA have a guarded ...
Doxey DL, Milne EM, Gilmour JS, Pogson DM.An attempt has been made to assess the diagnostic value of clinical features seen at initial examination of horses with grass sickness, colic cases and cases submitted as possible grass sickness but diagnosed subsequently as some other condition. There appears to be no single pathognomonic sign for grass sickness. A range of signs has been associated with grass sickness but these are of value only when related to the length of illness and the history. Biochemical tests related to intestinal tissue damage, stress and dehydration were evaluated and most were found to be of value in diagnosing ac...
van Rensburg IB, Volkmann DH, Soley JT, Stewart CG.A stud Clydesdale foal was still-born near full term. Macroscopic examination revealed a normal placenta, pulmonary atelectasis and faint white mottling of the kidneys. Microscopically there was severe lymphoplasmacytic interstitial nephritis. Numerous organisms resembling Encephalitozoon cuniculi were present in the affected kidneys. The organisms occurred in the areas of inflammation as well as in the renal glomeruli and intracellular cysts in the renal tubular epithelial cells and exhibited Gram positive staining. Ultrastructurally the organisms possessed a polar vacuole and a spiral filame...
Humber KA, Beech J, Cudd TA, Palmer JE, Gardner SY, Sommer MM.Azathioprine, a thiopurine antimetabolite used in the treatment of immune-mediated thrombocytopenia in human beings and dogs, was used in 2 cases of immune-mediated thrombocytopenia in horses that failed to respond to corticosteroid therapy alone. Platelet counts were increased to acceptable values in both horses. One horse returned to a successful racing career, and the other was euthanatized after developing renal disease and mild laminitis.
Hattel AL, Drake TR, Anderholm BJ, McAllister ES.Invasive pulmonary aspergillosis was detected at postmortem examination of an 8-year-old Quarter Horse mare that had a history of diarrhea, laminitis, and bilateral nasal discharge. A diagnosis of Ehrlichia risticii infection was made on the basis of clinical signs of diarrhea and pyrexia, high serum antibody titer to E risticii (1:2,560), and multiple Salmonella-negative cultures obtained from fecal and colonic specimens. Possible pathogenic mechanisms contributing to the development of pulmonary aspergillosis secondary to enteric disease include mycotic invasion of the intestinal tract or im...
Browning GF, Fitzgerald TA, Chalmers RM, Snodgrass DR.Equine rotavirus FI23 was shown to be prototypic of a novel G serotype, provisionally G14, by cross-neutralization and VP7 sequence determination. Although distinct, there are as few as six differing amino acid residues (92, 94, 96, 146, 147, and 221) in the VP7 antigenic regions of FI23 and G3 rotaviruses.
Stokes A, Corteyn AH, Murray PK.A group of three horses was experimentally infected with equine herpesvirus type 1 (EHV-1) and showed clinical signs characterised by a biphasic febrile response, leucopenia and cell associated viraemia accompanied by virus shedding from the nasopharynx. A second exposure to the virus 18 days later resulted in the isolation of virus from the nasopharynx of one horse. This and a further group of three EHV-1 seropositive horses were subsequently infected with equine herpesvirus type 4 (EHV-4) 147 days after the initial EHV-1 infection and virus was shed from the nasopharynx in the absence of cli...
Linke RP, Geisel O, Mann K.Amyloid deposits from equine cutaneous nodular amyloidosis associated with extramedullary plasmacytoma were classified immunohistochemically as equine immunoglobulin lambda-light chain-derived and designated eA lambda (HIP). For chemical identification, the amyloid fibril proteins were separated on Sephadex G-100 in 6M guanidine.HCl. Polypeptides of predominantly 24 kDa and 50 kDa were found by polyacrylamide gel electrophoresis. They have preponderance of immunoglobulin lambda-antigenic determinants as detected by immunodiffusion and immunoblotting. Since the N-terminus of the major proteins ...
Zhu D, Zeng ZL, Peng D, Chen X, Zhao LB, Zhang YY, Xu MM, Zhan QL, Yu JP, Xie P.To investigate the epidemiological pattern of Borna disease virus (BDV) infection in horses and to analyze the phylogenetic tree of derived BDV in Yili, Xinjiang. Methods: We established a modified nested RT-PCR (nRT-PCR) to detect BDV p24 segment in peripheral blood mononuclear cells (PBMCs) and brain tissues of 120 horses in Yili, Xinjiang. Positive products were analyzed by sequencing and homology analysis. Results: The positive rate of BDV infection was 2.5% in both PMBCs and brain tissues at the same time. The gene sequence revealed in positive PCR samples was more than 93%, identical to ...
Gliatto JM, Alroy J.A horse with malignant lymphoma (histiolymphocytic) and cutaneous amyloidosis is described. The lymphoma involved the dura mater of the spinal cord and some of the peripheral lymph nodes. Multifocal amyloid deposits were present in the skin and subcutis of the ventral abdomen but not within the lymphoma cell infiltrates or in the viscera.
Yuyama T, Yusa S, Yoshizumi K, Yamano S, Murata S, Hirose T, Osanai R, Onishi Y, Osato S, Sasaki C, Sasaki Y, Kakuda T, Tsubaki S, Takai S.The prevalence of virulent R. equi having 15- to 17-kDa antigens (VapA) in fecal isolates from 13 thoroughbred foals and their dams on 5 farms in Kagoshima, Japan, and the plasmid profiles of VapA-positive isolates by restriction fragment digestion patterns were investigated to compare the genotypic variation among virulence plasmids of R. equi isolates from Japan. In total, 218 (24.6%) of 886 isolates from the feces of the 13 foals and 13 (12.5%) of 104 isolates from the feces of their dams demonstrated VapA-positive R. equi. Plasmid DNA preparations of 231 virulent isolates from foals and da...
Seahorn JL, Slovis NM, Reimer JM, Carey VJ, Donahue JG, Cohen ND.To identify factors significantly associated with an epidemic of fibrinous pericarditis during spring 2001 among horses in central Kentucky. Methods: Case-control study. Methods: 38 horses with fibrinous pericarditis and 30 control horses examined for other reasons. Methods: A questionnaire was developed to solicit information regarding a wide range of management practices and environmental exposures from farm owners or managers. Results: The following factors were found in bivariate analyses to be significantly associated with an increased risk of pericarditis: being from a farm with mares an...
Gerard MP, Bowman KF, Blikslager AT, Tate LP, Bristol DG.To determine whether complete cecal bypass, by jejunocolostomy or ileocolostomy, is an effective treatment for horses with cecal impaction. Methods: Retrospective analysis of medical records. Methods: 9 horses with cecal impaction managed by jejunocolostomy (3) or ileocolostomy (6) performed with or without typhlotomy for evacuation of cecal contents. Methods: Information on age, breed, gender, duration of medical treatment, preoperative abnormalities, surgical procedure, and postoperative complications was retrieved from the medical records. Follow-up data were obtained via telephone intervie...
Rizzo D.An 11-year-old crossbred mare was presented with left eye buphthalmia, a mydriatic minimally responsive pupil, locally extensive ventral corneal edema, and corneal striae. Intraocular pressures exceeding 80 mmHg lead to a presumptive diagnosis of glaucoma. Following several days of treatment there was no improvement and enucleation was performed. Glaucome idiopathique chez une jument de race croisée âgée de 11 ans. Une jument de race croisée âgée de 11 ans a été présentée avec une buphtalmie de l’œil gauche, une pupille mydriatique minimalement réactive, un œdème cornéen ventr...
Kohn CW, Swardson C, Provost P, Gilbert RO, Couto CG.Myeloid and megakaryocytic bone marrow hypoplasia in association with moderate to profound neutropenia was observed in 8 young Standardbred horses sired by the same stallion; 7 horses were intermittently thrombocytopenic. Evaluation of serial neutrophil counts in 2 horses suggested that a cyclic variation in neutrophil numbers was present, that lymphocyte numbers increased when neutrophil counts decreased, and that platelet counts decreased when neutrophil counts decreased. Preliminary bone marrow cultures indicated that myeloid progenitor cells were present and that these cells were able to r...
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.
Andrews FM, Hamlin RL, Stalnaker PS.Whole blood viscosity (WBV) was measured on six healthy horses and ten horses presented for colic surgery. A Wells-Brookfield cone-and-plate microviscometer at 6 rpm was used to determine WBV and WBV was adjusted for packed cell volume (PCV). The ten colic horses were divided into two groups: five horses that died or were euthanatized (group 1) and five horses that were discharged after surgery and medical therapy (group 2). The mean WBV for each group was compared using analysis of variance followed by Duncan multiple-range tests. Mean WBV of group 2 (5.81 +/- 1.48 centipoise [cp]) and normal...
Kalinowski M, Grądzki Z, Jarosz Ł, Adaszek Ł.Rhodococcus equi (R. hoagii) is an opportunistic pathogen commonly found in foals up to 6 months old and animal environment. The R. equi genome contains genetically stable chromosomal DNA and an 80-90 kb plasmid containing vapA gene, responsible for virulence. Most reports from around the world focus on the determination of R. equi plasmid profiles. Few studies have attempted to determine differences in nucleotide sequences between virulent strains of R. equi isolated from foals and breeding environment. The aim of the study was to perform a molecular analysis of a fragment of the chromosomal ...