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.
MacKay RJ, Urquhart KA.Eight mature horses which had been affected with a moist cough for six weeks were found to have large numbers of eosinophils in tracheal mucus samples taken by transtracheal washing. These horses were kept on irrigated pasture and fed a hay-free diet. A companion yearling donkey was found to be passing Dictyocaulus arnfieldi larvae in its faeces. Two oral treatments with a dose of thiabendazole (440 mg/kg) resulted in the resolution of the clinical signs and the disappearance of eosinophils from transtracheal washings. The eosinophilic bronchitis seen in these horses was presumed to be a manif...
Amerault TE, Frerichs WM, Stiller D.An agglutinating antigen and a rapid card test (CT) for equine piroplasmosis was developed. The antigen for the CT was prepared from lyophilized Babesia caballi complement-fixation (CF) antigen. Serum and plasma samples for testing were obtained from known B caballi-infected horses and clinically normal horses maintained at the laboratory. Serum samples also were obtained from horses outside the continental United States, in areas where piroplasmosis is endemic. Comparative CT and CF tests were done on all samples. The CT correctly identified 85% of 192 plasma samples from known infected and n...
Taylor CE, Rosenthal RO, Taylor-Robinson D.The presence of allugtinins to the causative organism of contagious equine metritis (C.E.M.) in human serum has been confirmed. Agglutinins were found in the serum of 84 (37.6%) of 223 patients with non-gonococcal urethritis (N.G.U.), and in 12.5% of these patients there was a four-fold or greater rise in titre during the course of their illness. There was no evidence that these agglutinins were the result of infection by chlamydiae or ureaplasmas. Certain patients with these agglutinins seemed to respond better to therapy with antibiotics to which the C.E.M. bacterium is susceptible in vitro ...
Fernie DS, Cayzer I, Chalmers SR.A passive haemagglutination test (PHT) which has been developed for the detection of antibodies to the contagious equine metritis organism (CEMO) in serum is described. Samples from each of 30 mares with metritis were positive with titres in the range 256 to 4096. Samples from each of 239 clinically normal mares and 30 colts and fillies believed not to have been exposed to CEMO were negative with titres of less than 256, the majority of samples (97 per cent) showing a titre of 32 or less.
Dietz WH, Peralta PH, Johnson KM.The clinical and laboratory findings in ten humans infected with Venezuelan equine encephalitis virus, subtype I-D, are described in this report. Clinical and laboratory data indicate that, in contrast to equine infections, human infection with these enzootic virus strains (I-D) is similar to human infection with epizootic strains (I-ABC). In most cases there was an abrupt onset of fever, muscle pain, and vomiting. Virus was recovered from sera obtained during the first 3 days of illness. Lymphopenia occurred in all patients, and neutropenia occurred in three. No sequelae of these infections w...
Hughes JP.Contagious Equine Metritis (CEM) is a highly contagious venereal disease of horses caused by a fastidious, Gram-negative coccobacillus which grows best on chocolate agar under microaerophilic conditions (5-10% CO2). Clinically, the disease is characterized by a copious watery-to-mucopurulent, vaginal discharge two to ten days after breeding by an infected stallion (11, 13). Shortened estrous cycle lengths are common and may be the only indication of endometritis in some instances (7). Inapparent carriers of the disease in both the mare and stallion make control of the disease more difficult. O...
Charman H, Long C, Coggins L.Three structural proteins of equine infectious anemia virus were purified, labeled with 125I, and utilized in radioimmunoassays with horse sera and antisera to heterologous retroviruses. Whereas radioimmunoassay titers for the major protein, p25, were 500- to 1,000-fold higher than titers in immunodiffusion, for clinical purposes these two procedures were equivalent. Antibodies to two low-molecular-weight proteins, p12 and p10, were also found in infected horses, but with a lower frequency and lower titers. As a rule, only sera positive for p25 also contained antibody to p12 and p10. Antisera ...
Fretz PB, Babiuk LA, McLaughlin B.The serological results from this study clearly show that both equine influenza and equine rhinopneumonitis viruses were present during spring and autumn epidemics of respiratory disease on Western Canadian racetracks. Approximately 11% of the horses showed significant convalescent titres to influenza while 9% showed significant convalescent titres for equine viral pneumonitis. It was noted in our study a positive vaccination history corresponded with a reduction in the severity of the respiratory infection.
Issel CJ, Adams WV.In 1975, a survey was conducted in East Baton Rouge Parish, Louisiana, to determine the prevalence of equine infectious anemia. Using the agar gel immunodiffusion test, 94 of 1,398 horses (6.7%) were found to be infected. Infection rates were especially high in areas where clinical cases of equine infectious anemia had been diagnosed. Clinical signs compatible with the disease were noted in 1 of the 94 seropositive horses. The sample set of 1,398 horses represented 22% of the census population obtained during the 1971 Venezuelan equine encephalomyelitis vaccination campaign.
Cinco Del Fabbro M, Dougan R, Jelincic A, Piacentini I.The macroagglutination test, according Mailloux, was investigated for its feasibility in the rapid diagnosis of human and animal leptospirosis. Suspected sera examinated by Mailloux test, were also examinated by Complement Fixation and Microagglutination; the results suggest that: Mailloux macroagglutination is the serological test of choice, for screening of animal and human sera, mostly if it is not needed to know the infecting serovar.
Stratton LG, Corstvet R, Brown J, Corley L.K. pneumoniae capsule type 68 infused into the uterus of 4 mares was recovered up to 15 weeks after inoculation. The insertion of a tampon for 10 min was more effective than a swab technique in detecting the organism in the uterus. The clitoral fossa and the urethral orifice when sampled by the swab technique were also found to be infected for a comparable period. K. pneumoniae was isolated from the clitoral specimens more often and more consistently than from either urethral or uterine specimens.
Swerczek TW.Contagious Equine Metritis (CEM) was initially reported during the 1977 breeding season in England (Crowhurst, 1977) and Ireland (Timoney, Ward & Kelly, 1977. The disease has also been diagnosed in France and Australia (Huges, Bryden & MacDonald, 1978). The first occurrence of CEM in the United States followed the importation or 2 stallions from France late in 1977 which resulted in an outbreak early in the 1978 breeding season (Swerczek, 1978). Mares usually develop clinical signs of CEM 8--10 days after being covered by an infected stallion, when a copious, greyish discharge is seen. Other m...
Thomson GW, McCready R, Sanford E, Gagnon A.In the foaling season of 1977, five vaccinated horses in a Standardbred breeding stable were affected with herpesvirus myeloencephalitis. Respiratory and abortigenic forms also occurred in other individuals on the premises. Equine herpesvirus type 1 was isolated from the brain of one case of myeloencephalitis and from lungs of two aborted fetuses. Twelve of 16 horses demonstrated fourfold or greater increases in titres to equine herpesvirus type 1.
Dyke TM, Hinchcliff KW.Ceftiohr sodium was evaluated as a therapy for respiratory
infections in horses. This cephalosporin antimicrobial was
administered intramuscularly every 24 h and at a dose of 2.2
mglkg (1.0 mgllb) of body weight. The efficacy of ceftiofur
sodium was compared with that of a positive control drug,
ampicillin sodium (recommended dose of 6.6 mg/kg [3 mg/lb],
given every 12 h). Both treatments were continued for 48 h
after clinical symptoms were no longer evident (maximum of
10 days). Fifty-five (55) horses with naturally acquired
respiratory infections were included in the study; 28 were
...
Hu J, Brooks M, Fuller AL, Armstrong P, McDougald LR.Cultured Histomonas meleagridis cells were readily agglutinated in vitro by horse serum at concentrations as low as 5%, although clumping was more rapid and prominent at 15% or higher. For observation of clumping, the cultured organisms were washed twice in Hanks balanced solution (HBSS) by centrifugation (1,000 x g for 15 min) and filtered through glass wool. The test sera were added and the mixture incubated in a Petri plate or 24-well culture plates at r.t. for 15-30 min. Formation of clumps was time- and concentration-dependent. Gentle agitation hindered agglutination at low serum concentr...
Leifsson PS, Olsen SN, Larsen S.This paper is the first report of systemic tuberculosis involving the eyes in a horse. The animal lost condition and gradually became increasingly blind in both eyes; it was eventually euthanased. The pathological findings included bilateral, mycobacterial granulomatous uveitis with unilateral retinal detachment and necrosis, and disseminated, mycobacterial granulomatous foci in the myocardium, lungs, bronchial lymph nodes, kidneys, liver, pancreas, colon and visceral serosal surfaces, with the most extensive lesions in the myocardium. The mycobacteria were identified as Mycobacterium avium.
Samui KL, Gleiser RM, Hugh-Jones ME, Palmisano CT.A mosquito study based on collections from horse-baited stable traps was conducted in 1993 and 1994 at 3 sites in geographically and ecologically distinct areas of St. Tammany Parish (southeastern Louisiana) to determine the major horse-feeding mosquito species that could be possible bridging and epidemic vectors of eastern equine encephalomyelitis virus. A total of 4,535 mosquitoes in 1993 and 23,906 in 1994 involving 26 species were collected, of which, depending on the site, Culex salinarius, Cx. (Melanoconion) spp., Aedes vexans, Psophora ferox, Coquillettidia perturbans, Anopheles quadrim...
Marlow CH.Horse breeding in South Africa started in 1652, shortly after the 1st European settlement in the Cape. African horsesickness posed a serious problem and after a devastating outbreak of the disease in 1719, horses were largely replaced by oxen for agricultural and transport purposes but remained important from a sporting and military point of view. Examples of the latter are the export of horses for military use to India in the mid-19th century and for use in the Crimean War in 1854, reaching a zenith in the Anglo-Boer war in which an estimated 450 000 horses succumbed. Research and disease con...