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Topic:Infectious Disease
Infectious diseases in horses encompass a range of illnesses caused by bacteria, viruses, fungi, or parasites. These diseases can affect various systems within the equine body, leading to symptoms that range from mild discomfort to severe systemic illness. Common infectious diseases in horses include equine influenza, strangles, equine herpesvirus, and West Nile virus. These diseases can be transmitted through direct contact with infected animals, contaminated surfaces, or vectors such as insects. Understanding the mechanisms of transmission, pathogenesis, and immune response is essential for effective prevention and control. This page compiles peer-reviewed research studies and scholarly articles that explore the epidemiology, diagnosis, treatment, and management of infectious diseases in horses.
Actinomycosis of the mandible, mimicking a malignancy in a horse. Osteomyelitis of the mandible with Actinomyces species was diagnosed in a 4-year-old sports horse with radiographic changes suggestive of neoplasia. Surgical debridement, intravenous and local iodine solution treatment were administered. Mandibular Actinomyces infections are reported in humans and ruminants; they have not been previously reported in the horse. Actinomycose de la mandibule simulant une malignité chez un cheval. Une ostéomyélite de la mandibule à Actinomyces sp. a été diagnostiquée chez un cheval de sport âgé de 4 ans montrant des changements radiographiques ressemblant...
Serological changes observed in horses infected with Anoplocephala perfoliata after treatment with praziquantel and natural reinfection. The serological changes in two groups of horses known to be harbouring Anoplocephala perfoliata were studied; 12 were treated with 1.5 mg/kg praziquantel and 200 microg/kg ivermectin, and 14 were treated with 200 microg/kg ivermectin. Serological and faecal analyses were carried out on each animal at intervals for 758 days. The titres of antibodies specific for A perfoliata decreased from the day of treatment to day 28 in both groups, and continued to decrease in the group treated with praziquantel and ivermectin, with the first significant decrease from the other group at day 121. From day 15...
High subclinical West Nile virus incidence among nonvaccinated horses in northern California associated with low vector abundance and infection. Although horse cases frequently are reported during West Nile virus (WNV) outbreaks, few investigations have focused on the epidemiology of this transmission. From April to October 2003 to 2005, mosquito abundance and infection were monitored 3 days per week at an equine research facility at the University of California, Davis. Thirty-two nonvaccinated horses enrolled as controls in a vaccine study were bled monthly, and their serum was tested for evidence of WNV infection by plaque reduction neutralization test (PRNT). In 2004, one positive Culex pipiens pool was associated with a single hors...
Actinobacillus equuli subsp. equuli associated with equine valvular endocarditis. Microbiological and pathological data from a case of equine valvular endocarditis are reported. Limited information is available on the pathogenic potential of equine Actinobacillus species as several strains originate from apparently healthy horses. After the establishment of two subspecies within this species, this seems to be the first report of an etiological association between A. equuli subsp. equuli and equine endocarditis. Furthermore, new information on some phenotypical characteristics of this subspecies is reported, compared to previous findings.
Lymphangiosarcoma in the nictitating membrane of a horse. A 15-year-old Haflinger gelding presented with a mass in the left nictitating membrane. Two biopsies and the excised nictitating membrane were taken at different time points as a result of reoccurrence of the mass and submitted for histopathologic evaluation. The horse was euthanized as a result of poor prognosis following the reoccurrence of the mass after surgical removal. Histologically, the mass consisted of dilated, thin-walled vascular clefts and channels, lined by flattened to cuboidal endothelial cells with moderate cellular pleomorphism. There was up to 1 mitotic figure per high power...
Fatal pulmonary hemorrhage associated with RTX toxin producing Actinobacillus equuli subspecies haemolyticus infection in an adult horse. A case of fatal pulmonary hemorrhage in a 6-year-old American Paint mare with a 2-week history of intermittent coughing, fever, and epistaxis is described. Significant macroscopic abnormalities at postmortem examination were restricted to the respiratory system, and microscopically, severe pulmonary hemorrhage with suppurative bronchopneumonia was found. Actinobacillus equuli subsp. haemolyticus was cultured from a transtracheal wash performed antemortem as well as from the lungs at necropsy. The presence of airway-associated hemorrhage in conjunction with bacterial bronchopneumonia suggested ...
A comparison of coprological, serological and molecular methods for the diagnosis of horse infection with Anoplocephala perfoliata (Cestoda, Cyclophyllidea). Anoplocephala perfoliata (Cestoda, Cyclophyllidea), the commonest intestinal tapeworm of horses, can cause colic, intussusceptions, ileal impactions and intestinal perforations. Common diagnostic techniques for A. perfoliata infection, i.e. coprology and serology, show inherent limitations in terms of sensitivity and specificity and new approaches are thus required. Hence, the present study compared the reliability of coprological, serological (i.e. ELISA) and molecular (i.e. nested PCR) methods in detecting A. perfoliata infection in naturally infected horses and in horses treated with a comb...
Streptococcus henryi sp. nov. and Streptococcus caballi sp. nov., isolated from the hindgut of horses with oligofructose-induced laminitis. Four Gram-positive, catalase-negative, coccoid-shaped isolates were obtained from the caecum and rectum of horses with oligofructose-induced equine laminitis. Phenotypic and phylogenetic studies were performed on these isolates. Initial biochemical profiling assigned two of the isolates to Streptococcus bovis. The other two isolates, however, could not be assigned conclusively on the basis of their biochemical profiles. Gene sequence analysis demonstrated that the four new isolates were related most closely to Streptococcus suis based on the 16S rRNA gene and to Streptococcus orisratti based o...
Cystic echinococcosis in equids in Italy. Between March 2003 and February 2007, the livers and the lungs of 2,231 horses from various Italian regions were examined for cystic echinococcosis presence at the time of slaughter. Hydatid cysts were found in six horses, namely four from Sardinia, one from Sicily, and one from Tuscany. The location, number, morphology, and fertility of the cysts found were determined. DNA was extracted from the germinal layers and protoscoleces of the fertile cysts and polymerase chain reactions (PCR) were performed in order to strain type DNA isolates for reduced nicotinamide adenine dinucleotide dehydrogen...
Molecular cloning and characterization of the alphaX subunit from CD11c/CD18 horse integrin. This work reports the cloning and sequence determination of the horse alpha subunit of the integrin CD11c/CD18, a marker of dendritic cells. A cDNA clone of 4582 base pairs was obtained. It encodes a protein segment of 1086 amino acid residues of the extracellular domain with 10 potential sites of glycosylation, a transmembrane domain of 32 residues and a C-terminal cytoplasmic tail of 24 residues. A phylogenetic analysis of this integrin shows close similarity (83%) with that of Canis familiaris.
Early migration of Sarcocystis neurona in ponies fed sporocysts. Sarcocystis neurona is the most important cause of equine protozoal myeloencephalitis (EPM), a neurologic disease of the horse. In the present work, the kinetics of S. neurona invasion is determined in the equine model. Six ponies were orally inoculated with 250 x 10(6) S. neurona sporocysts via nasogastric intubation and killed on days 1, 2, 3, 5, 7, and 9 postinoculation (PI). At necropsy, tissue samples were examined for S. neurona infection. The parasite was isolated from the mesenteric lymph nodes at 1, 2, and 7 days PI; the liver at 2, 5, and 7 days PI; and the lungs at 5, 7, and 9 days ...
Seroprevalence of equine babesiosis in the Black Sea region of Turkey. The prevalence of Theileria equi and Babesia caballi was determined in equid blood samples in five provinces of the Black Sea region of Turkey by using the indirect fluorescent antibody test (IFAT). Of 153 samples, 53 (34.6%) and 33 (21.5%) were seropositive to B. caballi and T. equi, respectively. In addition, 8 (5.2%) of samples were seropositive to both T. equi and B. caballi. Anti T. equi and B. caballi antibodies were detected in all five regions. The prevalence of B. caballi was higher than T. equi in all counties. Antibodies to T. equi and B. caballi were detected in horses of all ages,...
Brown-headed cowbirds (Molothrus ater) harbor Sarcocystis neurona and act as intermediate hosts. We tested the hypothesis that brown-headed cowbirds (Molothrus ater) harbor Sarcocystis neurona, the agent of equine protozoal myeloencephalitis (EPM), and act as intermediate hosts for this parasite. In summer 1999, wild caught brown-headed cowbirds were collected and necropsied to determine infection rate with Sarcocystis spp. by macroscopic inspection. Seven of 381 (1.8%) birds had grossly visible sarcocysts in leg muscles with none in breast muscles. Histopathology revealed two classes of sarcocysts in leg muscles, thin-walled and thick-walled suggesting two species. Electron microscopy sh...
Virus recovery rates for wild-type and live-attenuated vaccine strains of African horse sickness virus serotype 7 in orally infected South African Culicoides species. Previously reported virus recovery rates from Culicoides (Avaritia) imicola Kieffer and Culicoides (Avaritia) bolitinos Meiswinkel (Diptera, Ceratopogonidae) orally infected with vaccine strain of African horse sickness virus serotype 7 (AHSV-7) were compared with results obtained from concurrently conducted oral infections with five recent AHSV-7 isolates from naturally infected horses from various localities in South Africa. Culicoides were fed sheep bloods spiked with 10(7.6) TCID(50)/mL of a live-attenuated vaccine strain AHSV-7, and with five field isolates in which virus titre in the blo...
Rickettsia infection in five areas of the state of São Paulo, Brazil. This study investigated rickettsial infection in animals, humans, ticks, and fleas collected in five areas of the state of São Paulo. Eight flea species (Adoratopsylla antiquorum antiquorum, Ctenocephalides felis felis, Polygenis atopus, Polygenis rimatus, Polygenis roberti roberti, Polygenis tripus, Rhopalopsyllus lugubris, and Rhopalopsyllus lutzi lutzi), and five tick species (Amblyomma aureolatum, Amblyomma cajennense, Amblyomma dubitatum, Ixodes loricatus, and Rhipicephalus sanguineus) were collected from dogs, cats, and opossums. Rickettsia felis was the only rickettsia found infecting ...
Prevalence of latent, neuropathogenic equine herpesvirus-1 in the Thoroughbred broodmare population of central Kentucky. An emerging problem of equine herpesvirus-1 (EHV-1) infection in horses in the USA is a high-mortality myeloencephalopathy that commonly occurs where large numbers of horses are stabled. EHV-1 isolates recovered from recent neurological outbreaks represent a mutant virus strain that possesses enhanced neuropathogenicity. A central question of EHV-1 myeloencephalopathy is the latency carriage rate for these mutants of EHV-1 in USA horse populations. Objective: To estimate the prevalence of neuropathogenic strains of EHV-1 as latent infections in the Thoroughbred broodmare population of central ...
Ocular penetration of intravenously administered enrofloxacin in the horse. Information on antibiotic concentrations in the equine eye following systemic therapy is limited. Reports that Leptospira spp. are frequently present in the eyes of horses with recurrent uveitis, emphasises a need for studies on ocular concentrations of specific antibiotics. Objective: 1) Enrofloxacin, administered i.v. at 7.5 mg/kg bwt q. 24 h, results in aqueous humour concentrations greater than the reported minimum inhibitory concentration (MIC) for Leptospira pomona. 2) Aqueous humour paracentesis sufficiently disrupts the blood-aqueous humour barrier (BAB) to cause an increase in aqueous...
Sequential analysis of Anaplasma phagocytophilum msp2 transcription in murine and equine models of human granulocytic anaplasmosis. Anaplasma phagocytophilum causes human granulocytic anaplasmosis by inducing immunopathologic responses. Its immunodominant Msp2 protein is encoded by a family of >100 paralogs. Msp2 (msp2) expression modulates in the absence of immune pressure, and prolonged in vitro passage modulates in vivo virulence. Because programmed MSP2 expression occurs in Anaplasma marginale, we hypothesized a similar event in A. phagocytophilum in vivo, with specific Msp2 expression triggering immunopathologic injury or clinical manifestations of disease. We examined msp2 transcripts in 11 B6 mice and 6 horses inocu...
Equine travellers to the Olympic Games in Hong Kong 2008: a review of worldwide challenges to equine health, with particular reference to vector-borne diseases. The past 10-20 years have seen exponential growth in the volume of trade in horses and equine germplasm; and the extent of global horse movements has increased significantly in the last 4 years. In preparing for the transport of elite Olympic horses to Hong Kong in 2008, it will be very important to be as fully informed as possible of the disease situation in both the exporting and importing country, import and re-entry requirements, as well as having a vaccination strategy to protect against particular diseases. In this context the review describes the equine vector-borne disease situation in...
Prevalence of Setaria equina microfilaraemia in horses in Hungary. Peripheral blood samples were collected randomly from 195 horses in various parts of Hungary, and the presence of microfilariae was evaluated by the Knott technique. On the basis of morphological identification 18 of the horses (9.2 per cent) were infected with Setaria equina, and the infection was confirmed in 10 animals by pcr and sequencing. The level of microfilaraemia was between 1 and 1138 larvae in 2 ml of blood. There was no correlation between the time of sampling or the sex of the animals (stallions versus mares) and the prevalence of infection, but the prevalence decreased with age....
A multicenter case-control study of risk factors for equine protozoal myeloencephalitis. To identify risk factors for equine protozoal myeloencephalitis (EPM) among horses examined at 11 equine referral hospitals. Methods: Case-control study. Methods: 183 horses with EPM, 297 horses with neurologic disease other than EPM (neurologic controls), and 168 horses with non-neurologic diseases (non-neurologic controls) examined at 11 equine referral hospitals in the United States. Methods: A study data form was completed for all horses. Data were compared between the case group and each of the control groups by means of bivariate and multivariate polytomous logistic regression. Results: ...
Comparative efficacy of diminazene diaceturate and diminazene aceturate for the treatment of babesiosis in horses. The present work was conducted to study the comparative efficacy of two anti-protozoan (babesicidal) drugs on the recovery and health of horses. A total of 80 horses, showing typical clinical symptoms of the disease, were selected for this study; the presence of babesiosis was confirmed through blood smear examination. These animals were divided into two groups i.e. A and B. Horses of Group A, were treated with diminazene diaceturate, while horses of Group B were treated with diminazene aceturate. Efficacy of the drugs was determined by the reversal of clinical signs and a negative blood smear...
Safety of an attenuated West Nile virus vaccine, live Flavivirus chimera in horses. West Nile virus (WNV) infection is endemic and able to cause disease in naive hosts. It is necessary therefore to evaluate the safety of new vaccines. Objective: To establish: 1) the safety of a modified live Flavivirus/West Nile virus (WN-FV) chimera by administration of an overdose and testing for shed of vaccine virus and spread to uninoculated sentinel horses; 2) that this vaccine did not become pathogenic once passaged in horses; and 3) vaccine safety under field conditions. Methods: There were 3 protocols: 1) In the overdose/shed and spread study, horses were vaccinated with a 100x immun...
Interpretation of serum antibody response to Anoplocephala perfoliata in relation to parasite burden and faecal egg count. Increased knowledge is needed to assist in the interpretation of presently available diagnostic techniques for infection by the tapeworm Anoplocephala perfoliata in horses. Objective: The suggested cut-off level of an A. perfoliata specific ELISA may not adequately reflect the actual infection level. Hence, faecal egg counts may be a more useful diagnostic test for individual horses than previously reported. Methods: Eighty-four horses admitted for slaughter at a Danish abattoir were examined for the presence of A. perfoliata. The number of tapeworms, their stage of development and gross patho...
Efficacy, duration, and onset of immunogenicity of a West Nile virus vaccine, live Flavivirus chimera, in horses with a clinical disease challenge model. West Nile virus (WNF) is a Flavivirus responsible for a life-threatening neurological disease in man and horses. Development of improved vaccines against Flavivirus infections is therefore important. Objective: To establish that a single immunogenicity dose of live Flavivirus chimera (WN-FV) vaccine protects horses from the disease and it induces a protective immune response, and to determine the duration of the protective immunity. Methods: Clinical signs were compared between vaccinated (VACC) and control (CTRL) horses after an intrathecal WNV challenge given at 10 or 28 days, or 12 months p...
Granulomatous nephritis and meningoencephalomyelitis caused by Halicephalobus gingivalis in a pony gelding. A ten-year-old Shetland pony gelding showed low appetite, ataxia, peculiar swaying, clouding of consciousness, and ultimately died. At necropsy, multiple coalescing granulomatous foci were detected in the kidneys, and small necrotic lesions were found in the cerebellum. Histologic examination of the renal tissue sections revealed extensive granuloma, and Halicephalobus gingivalis-like nematodes were seen. Similar nematodes were found in the granulomatous or necrotic lesions of the renal lymph nodes and cerebellum, and were also frequently detected in cerebrospinal meningovascular lesions. Morp...
Factors associated with West Nile virus disease fatalities in horses. In 2003, the occurrence and location of horses with clinical signs of West Nile virus infection were identified in the southern portion of Saskatchewan with the help of veterinarians, owners, and the regional laboratory. A total of 133 clinical cases were reported between July 30 and September 19, 2003; however, postseason surveillance suggests that the number of cases was underestimated. The case fatality rate was 43.8% (95% CI 35.2, 52.4). Factors associated with fatality in clinical cases included sex, week of onset of clinical signs, and coat color. Reported clinical cases clustered within...
