Pathogenesis in horses refers to the biological mechanisms that lead to the development and progression of diseases within equine species. This process involves a complex interaction between the horse's immune system, genetic predispositions, environmental factors, and infectious agents such as bacteria, viruses, or parasites. Understanding pathogenesis is essential for identifying how diseases manifest and progress in horses, which can inform diagnostic and therapeutic strategies. Research in this area often focuses on specific diseases, examining factors such as pathogen entry, immune response, tissue damage, and recovery processes. This page compiles peer-reviewed research studies and scholarly articles that explore the mechanisms, contributing factors, and implications of pathogenesis in equine health.
Hooper PT.Severe spongy degeneration of the central nervous system (CNS) was seen in 11 cattle, 19 sheep, 4 pigs and 1 goat, associated with a variety of hepatic diseases, particularly those caused by hepatotoxic pyrrolizidine alkaloids. It was also seen in a milder form in 2 of 8 horses examined, 1 dog of 5 dogs examined, and in 1 rabbit only of a large number of laboratory animals examined. This paper reports results of experiments which confirmed initially that the CNS disease cold be caused by pyrrolizidine alkaloid intoxication. This was done by poisoning lambs with lasiocarpine. As the disease was...
Platt H, Whitwell KE.A form of generalized fat necrosis and steatitis occurs in pony and donkey foals. The clinical and pathological features of this disorder are described and its possible relationship to a similar condition in the Thoroughbred foal, and to yellow Fat Disease in other species, is discussed.
Heydrick FP, Comer JF, Wachter RF.Phospholipid analyses of Venezuelan equine encephalitis virus showed that virus propagated in L-cell monolayers had a higher sphingomyelin content and a lower phosphatidylcholine content than virus grown in chick fibroblast monolayers. Virus of L-cell origin also was found to possess greater thermal stability than virus derived from the chick fibroblast cell.
Henderson BE, Chappell WA, Johnston JG, Sudia WD.Henderson, B. E., W. A. Chappell, J. G. Johnston, Jr. and W. D. Sudia (CDC, Atlanta, Ga. 30333). Experimental Infection of horses with three strains of Venezuelan equine encephalomyelitis virus. I. Clinical and virological studies. Amer J Epidem 93: 194–205, 1971.—Clinical effect, viremias and antibody responses were compared in horses inoculated with the following strains of Venezuelan equine encephalomyelitis (VEE) virus: Fe3-7C, isolated from Culex (Melano-conion) spp. mosquitoes collected In 1963 in the Florida Everglades; TC-83, the Fort Detrick live, attenuated vaccine strain; and GJ...
Marois P, Boudreault A, DiFranco E, Pavilanis V.Rhesus monkeys and ferrets were exposed to intranasal inoculation of several strains of egg-adapted avian, equine and human influenza viruses and to strains of mouse-adapted equine influenza viruses. Local replication of virus and seroconversion were observed in the majority of these animals. However, clinical infection was observed only in ferrets.
Yager JA, Foster SF, Zink MC, Prescott JF, Lumsden JH.Polymorphonuclear leukocytes from adult horses were separated from whole blood, using a 2-step Percoll gradient, and were tested for bactericidal function against Corynebacterium equi. Staphylococcus aureus, an organism against which equine neutrophils have proved efficacy, was a positive control. The percentage of uptake after a 15-minute preincubation of the neutrophils and bacteria in the presence of normal horse serum was also calculated. The results indicated that equine neutrophils effectively phagocytosed and killed C equi and S aureus. The percentage of uptake for S aureus (95% +/- 3%)...
Kaname Y, Celma CCP, Kanai Y, Roy P.African horse sickness virus (AHSV) is an insect-vectored emerging pathogen of equine species. AHSV (nine serotypes) is a member of the genus Orbivirus, with a morphology and coding strategy similar to that of the type member, bluetongue virus. However, these viruses are distinct at the genetic level, in the proteins they encode and in their pathobiology. AHSV infection of horses is highly virulent with a mortality rate of up to 90 %. AHSV is transmitted by Culicoides, a common European insect, and has the potential to emerge in Europe from endemic countries of Africa. As a result, a safe an...
Mehdizadeh Gohari I, Parreira VR, Nowell VJ, Nicholson VM, Oliphant K, Prescott JF.A role for type A Clostridium perfringens in acute hemorrhagic and necrotizing gastroenteritis in dogs and in necrotizing enterocolitis of neonatal foals has long been suspected but incompletely characterized. The supernatants of an isolate made from a dog and from a foal that died from these diseases were both found to be highly cytotoxic for an equine ovarian (EO) cell line. Partial genome sequencing of the canine isolate revealed three novel putative toxin genes encoding proteins related to the pore-forming Leukocidin/Hemolysin Superfamily; these were designated netE, netF, and netG. netE a...
Zynda HM, Scare JA, Steuer AE, Anderson HP, Nielsen MK.Cyathostomins are pervasive equine parasites in horses across the world, and larval stages are known to cause the deadly disease larval cyathostominosis. The mucosal digestion technique is widely used for enumeration of encysted larval stages. Previous studies have investigated the spatial variation of encysted larvae, however current protocols lack a description of a standardized area from which to take the tissue sample. This study sought to evaluate spatial variation in encysted cyathostomin larval counts among the large intestinal organs and their subsections. Following humane euthanasia, ...
Rüfenacht S, Marti E, von Tscharner C, Doherr MG, Forster U, Welle M, Roosje PJ.The pathogenesis of equine urticaria is not well understood. In man, urticaria has been associated with immunological and nonimmunological mechanisms leading to the release of various mediators by mast cells. Skin biopsies of 32 horses with a history of urticaria were stained with toluidine blue, a double-labelling method for chymase and tryptase, and immunohistochemistry for immunoglobulin (Ig)E. These horses were compared with horses with pemphigus foliaceus, insect bite hypersensitivity and control horses with healthy skin. Neither formalin fixation time nor biopsy site influenced the stain...
van Kasteren PB, Bailey-Elkin BA, James TW, Ninaber DK, Beugeling C, Khajehpour M, Snijder EJ, Mark BL, Kikkert M.Protein ubiquitination regulates important innate immune responses. The discovery of viruses encoding deubiquitinating enzymes (DUBs) suggests they remove ubiquitin to evade ubiquitin-dependent antiviral responses; however, this has never been conclusively demonstrated in virus-infected cells. Arteriviruses are economically important positive-stranded RNA viruses that encode an ovarian tumor (OTU) domain DUB known as papain-like protease 2 (PLP2). This enzyme is essential for arterivirus replication by cleaving a site within the viral replicase polyproteins and also removes ubiquitin from cell...
Gao X, Jiang CG, Han XE, Zhao LP, Shen RX, Xiang WH, Zhou JH.To elucidate the function of the S2 gene in equine infectious anemia virus (EIAV) and its role in the attenuation of the Chinese attenuated EIAV vaccine strains, the S2 in the EIAV vaccine strain EIAV (FDDV) was reverse-mutated and the in vitro replication character of the resultant virus was evaluated. Based on the sequence variation of the S2 gene between the EIAV virulent strains and vaccine strains, all the four vaccine-specific sites in the S2 of an EIAV(FDDV) infectious clone, pFDDV3-8, were reverse-mutated to the sequences of the virulent strain EIAV(DV115). The reverse-mutated molecula...
Camp CJ, Leid HW.Extracts of Onchocerca cervicalis, an equine parasite, were incubated with radiolabeled equine neutrophils and neutrophil migration was assessed for factors derived from the parasite itself or for host-derived factors after incubation of these same parasite extracts with equine serum. No stimulus for cell migration was observed in saline extracts of adult worms, uterine microfilariae, or skin microfilariae at any dosage tested. However, after incubation of saline extracts with fresh normal equine sera a marked stimulus for neutrophil migration was observed. Ablation of this biologic activity w...
Fink C, Tatar M, Failing K, Hospes R, Kressin M, Klisch K.Serotonin (5-hydroxytryptamine, 5-HT), a regulatory amine of mucosal enterochromaffin cells plays an important role in the control of gastrointestinal smooth muscle contraction and epithelial secretion. Serotonin has also been associated with gastric ulcers, diarrhoea and abdominal pain. In spite of the high incidence of these gastrointestinal disorders in newborn foals and adult horses, no data are available regarding 5-HT immunoreactive cells (i.c.) in the gastrointestinal tract (GIT) of foals, and for adult horses, data are incomplete and contradictory. In this study, the distribution and r...
Greenaway EC, Sepulveda MF, Cunningham FM, Goode NT.Eosinophils have been implicated in the pathogenesis of the seasonal equine allergic skin disease, sweet itch. Protein kinase C (PKC) is involved in regulating eosinophil function and antigen challenge has been reported to alter PKC isotype expression in blood eosinophils from allergic human subjects. Here we have compared the pattern of PKC isotype expression in eosinophils from sweet itch ponies with that in cells from normal ponies both during the active and inactive phases of the disease. A role for PKC in histamine-induced eosinophil activation was also investigated. Conventional PKCs alp...
Adeyefa CA.The clinicopathological features and treatment of cases of dermatomycotic infections in horses are reported. Organisms isolated from these cases include Trichophyton mentagrophyte, T. equinum and Micosporum equinum. The Veterinary, medical and economic importance of the disease is discussed.
García-Tamayo J.Clinical findings on Venezuelan Equine Encephalitis virus infection and the teratogenic effects of several Togaviruses are described. Similarities between the intrauterine alterations induced by Venezuelan Equine Encephalitis virus and rubella virus are pointed out. Findings described by Wenger in 1967 were those of massive cerebral necrosis in fetuses of women presumably suffering of encephalitis and they are commented along with the development of an animal experimental model at the end of 1970-1980. Pathogenesis of the intrauterine infection seemed to be related to changes in the placental ...
Woollam DH.The history of teratology is reviewed. Methods available for causing malformations in mammals by subtle changes in the environment during pregnancy are discussed. A table is provided in which the commoner teratogens are listed. Methods are described by means of which the activity of some common teratogens may be opposed. The occurrence at Battle Creek, Michigan, USA, of a chemical agent dangerous to health, life and development of all mammals is described. This gives an indication that injury and death to all mammals, as in the Sevaso disaster, including teratogenesis may be expected to be a f...
Moore BD, Balasuriya UB, Hedges JF, MacLachlan NJ.Equine viral arteritis (EVA) is an endotheliotropic viral disease of horses caused by equine arteritis virus (EAV). Although there is only one serotype of EAV, there is marked variation in the virulence of different strains of the virus. The replication and cytopathogenicity of three well-characterized strains of EAV of different virulence to horses were compared in rabbit kidney (RK-13) and primary equine pulmonary artery endothelial cells (ECs). Viral protein expression, plaque size, and cytopathogenicity of all three viruses were similar in RK-13 cells, whereas two virulent strains of EAV w...
Franzén P, Berg AL, Aspan A, Gunnarsson A, Pringle J.A 19-year-old horse that was one of a group of six horses infected experimentally with Anaplasma phagocytophilum for a study of the pathogenesis of equine granulocytic ehrlichiosis died suddenly two days after first showing clinical signs of disease. The clinical signs and laboratory findings observed before its death were similar to all those of the other infected horses, and to previous reports of this disease. A postmortem examination revealed widespread haemorrhaging in its internal organs, and vasculitis and thrombosis in the kidneys. These changes are consistent with disseminated intrava...
Marchi PR, Rawlings P, Burroughs JN, Wellby M, Mertens PP, Mellor PS, Wade-Evans AM.Purified African horse sickness virus (AHSV) was fed, as part of a blood meal, to adult females from a susceptible colony of Culicoides variipennis, established in the insectories at the Institute for Animal Health, Pirbright Laboratory, UK. The meal consisted of heparinized blood obtained from ovine, bovine, equine (horse and donkey) or canine sources spiked with AHSV serotype 9 (AHSV9). The infectivity levels observed for C. variipennis varied significantly, according to the source of the blood sample. Comparison of the protein profiles obtained from AHSV9 incubated with the individual serum...
Bentinck-Smith J, Tasker JB.The following topics are discussed in this presentation: A. Recent advances in the use and interpretation and methodology of antibiotic susceptibility testing. B. Improvements in sample submittal to obtain accurate results from your laboratory. C. Staining blood, bone marrow, and cytology specimens in the office laboratory. D. Pathogenesis and differential diagnosis of lipemia. E. Differential diagnosis of abdominal effusions.
Hébert L, Rincé I, Sanna C, Laugier C, Rincé A, Petry S.The genus Taylorella is composed of two species: (i) Taylorella equigenitalis, the causative agent of CEM, a venereally transmitted infection of Equidae and (ii) Taylorella asinigenitalis, a closely related species considered to be nonpathogenic, although experimental infection of mares with this bacterium resulted in clinical signs of vaginitis, cervicitis or endometritis. Currently, there is a need for an alternative host model to further study the taylorellae species. In this context, we explored Galleria mellonella larvae as potential alternative model hosts for taylorellae. Our results sh...
Journal of proteomicsJanuary 3, 2017
Volume 154 102-108 doi: 10.1016/j.jprot.2016.12.015
Degroote RL, Uhl PB, Amann B, Krackhardt AM, Ueffing M, Hauck SM, Deeg CA.The membrane protein expression repertoire of cells changes in course of activation. In equine recurrent uveitis (ERU), a spontaneous autoimmune disease in horses with relapsing and ultimately blinding inner eye inflammation, CD4+ T lymphocytes are the crucial pathogenic cells activated in the periphery directly prior to an inflammatory episode. In order to find relevant changes in the membrane proteome associated to disease, we sorted CD4+ lymphocytes and compared protein abundance from the generated proteome datasets of both healthy horses and ERU cases. We detected formin like 1, a key play...
Strand E, Fjordbakk CT, Sundberg K, Spangen L, Lunde H, Hanche-Olsen S.Two genetically and phenotypically distinct horse breeds are used for harness racing in Scandinavia: the Standardbred (SB) and Coldblooded Trotter. These racehorses have identical environmental, management and racing conditions. Therefore, this study was undertaken to identify and compare the relative prevalence of upper respiratory tract (URT) obstructive disorders in these 2 breeds. Objective: To determine whether these 2 phenotypically different breeds of harness racehorses have different predispositions for URT disorders. Methods: Retrospective study of 88 Norwegian Coldblooded Trotters (N...
Swadzba ME, Hirmer S, Amann B, Hauck SM, Deeg CA.Although the presence of IgG autoantibodies in the vitreous of spontaneous cases of equine recurrent uveitis (ERU) has been demonstrated, the potential role of IgM reactivities during ERU pathogenesis remains unexplored. The purpose of this study was to examine the presence of IgM autoantibodies in vitreous specimens of ERU-affected horses and to test their binding specificity to intraocularly expressed proteins. Methods: To test IgM autoantibody responses to retinal tissue, vitreous samples of eye-healthy controls and ERU patients were analyzed via two-dimensional Western blot analysis with e...
Dimock AN, Siciliano PD, McIlwraith CW.Reactive oxygen species (ROS) are capable of degrading many components of the joint in the presence of insufficient antioxidant defences, and as a result have been implicated in the pathogenesis of joint disease in horses. However, to our knowledge, evidence of ROS occurring in diseased joints of horses has not been reported. The objective of this experiment was to compare differences in synovial fluid protein carbonyl content (as a marker of oxidative modification of synovial fluid proteins by ROS) and the antioxidant status of synovial fluid between clinically normal and diseased equine join...
Hooper PT.Severe spongy degeneration of the central nervous system (CNS) was seen in 11 cattle, 19 sheep, 4 pigs and 1 goat, associated with a variety of hepatic diseases, particularly those caused by hepatotoxic pyrrolizidine alkaloids. It was also seen in a milder form in 2 of 8 horses examined, 1 dog of 5 dogs examined, and in 1 rabbit only of a large number of laboratory animals examined. This paper reports results of experiments which confirmed initially that the CNS disease cold be caused by pyrrolizidine alkaloid intoxication. This was done by poisoning lambs with lasiocarpine. As the disease was...
Dunkel B, Rickards KJ, Werling D, Page CP, Cunningham FM.Recurrent airway obstruction (RAO) in mature horses is characterized by reversible airway obstruction and neutrophilic inflammation; there is also functional activation of circulating platelets and neutrophils. This study was undertaken to determine if changes in activation marker expression and heterotypic aggregate formation can be used as an indicator of this increased functional responsiveness. In vitro conditions for flow cytometric measurement of CD13, CD41/61 and CD62P expression on activated cells and heterotypic aggregate formation were established. Values were then compared before an...
Holcombe SJ, Derksen FJ, Robinson NE.Determining the respiratory related activity of the palatinus and palatopharyngeus muscles in exercising horses is relevant because dysfunction of these muscles has been implicated in the pathogenesis of dorsal displacement of the soft palate. Objective: To determine if the palatinus and palatopharyngeus muscles have respiratory activity that increases with intensity in exercising horses. Methods: Electromyographic activity was measured in the palatinus and palatopharyngeus muscles using bipolar fine-wire electrodes while the horses completed an incremental exercise treadmill protocol. Results...
Barlaam A, Traversa D, Papini R, Giangaspero A.Over the past few decades, among equine parasitoses caused by gastrointestinal nematodes, habronematidosis has been discontinuously studied worldwide. Habronematidosis is a parasitic disease distributed all over the world. It is caused by Habronema microstoma, Habronema muscae, and Draschia megastoma (Spirurida, Habronematidae), and it is maintained in the environment by muscid flies which act as intermediate hosts. At larval and adult stages these species live in the stomach of domestic and wild equids. However, the larvae can also be found on the skin, causing lesions known as "summer sores"...
Neely M, Arroyo L, Jardine C, Clow K, Moore A, Hazlett M, Weese JS.The blacklegged tick (), which transmits , the causative agent of Lyme disease, has undergone rapid range expansion in Ontario. In horses, Lyme disease remains an enigmatic disease, with limited understanding of the pathogenesis and many issues pertaining to selection and interpretation of laboratory tests. We evaluated seropositivity in naturally exposed horses over a 12-mo period and compared paired samples with 2 common serologic tests. Serum samples were collected in 2017, ~1 y after initial testing, from a cohort of 22 horses that were seropositive in a 2016 seroprevalence study. Sampl...
Jonsdottir S, Hamza E, Janda J, Rhyner C, Meinke A, Marti E, Svansson V, Torsteinsdottir S.Insect bite hypersensitivity (IBH) is an allergic dermatitis of horses caused by bites of midges (Culicoides spp.). IgE-mediated reactions are often involved in the pathogenesis of this disease. IBH does not occur in Iceland due to the absence of Culicoides, but it occurs with a high frequency in Icelandic horses exported to mainland Europe, where Culicoides are present. We hypothesize that immunization with the Culicoides allergens before export could reduce the incidence of IBH in exported Icelandic horses. The aim of the present study was therefore to compare intradermal and intralymphatic ...
Gerhard AP, Krücken J, Heitlinger E, Janssen IJI, Basiaga M, Kornaś S, Beier C, Nielsen MK, Davis RE, Wang J, von Samson-Himmelstjerna G.P-glycoproteins (Pgp) have been proposed as contributors to the widespread macrocyclic lactone (ML) resistance in several nematode species including a major pathogen of foals, Parascaris univalens. Using new and available RNA-seq data, ten different genomic loci encoding Pgps were identified and characterized by transcriptome-guided RT-PCRs and Sanger sequencing. Phylogenetic analysis revealed an ascarid-specific Pgp lineage, Pgp-18, as well as two paralogues of Pgp-11 and Pgp-16. Comparative gene expression analyses in P. univalens and Caenorhabditis elegans show that the intestine is the maj...
Equine recurrent uveitis serves as a spontaneous model for human autoimmune uveitis. Unpredictable relapses and ongoing inflammation in the eyes of diseased horses as well as in humans lead to destruction of the retina and finally result in blindness. However, the molecular mechanisms leading to inflammation and retinal degeneration are not well understood. An initial screening for differentially regulated proteins in sera of uveitic cases compared to healthy controls revealed an increase of the alternative pathway complement component factor B in ERU cases. To determine the activation status ...
