Topic:Pathogens
Pathogens are microorganisms, such as bacteria, viruses, fungi, and parasites, that can cause disease in horses. These microorganisms interact with the equine immune system, often leading to a range of health issues that can affect individual horses or entire populations. Pathogens can be transmitted through various routes, including direct contact, vectors, or environmental exposure. Common equine pathogens include Streptococcus equi, Equine Herpesvirus, and Strongylus vulgaris. Understanding the interactions between equine hosts and pathogens is essential for disease prevention, management, and treatment. This page compiles peer-reviewed research studies and scholarly articles that explore the identification, transmission, and impact of pathogens on equine health.
Klebsiella and Enterobacter organisms isolated from horses. An account is given of K. pneumoniae capsule types occurring in horses, with particular reference to strains originating from the genital tract in the mare and the external genitalia of the stallion. A survey of the prevalence of K. pneumoniae and E. aerogenes strains in the preputial flora of healthy stallions is described. The majority of horses were found to be carriers of these organisms. The cultural characteristics of these preputial strains are described and compared with those of K. pneumoniae strains associated with epidemic metritis in mares. The epidemiological significance of certa...
The capybara (Hydrochoerus hydrochaeris) as a reservoir host for Trypanosoma evansi. Discovery of two ill horses and three dogs naturally infected with Trypanosoma evansi near an experimental station in the Eastern Plains of Colombia led to a search for reservoir hosts of the parasite. Infection was detected in 8/33 healthy capybaras (Hydrochoerus hydrochaeris), none of the remaining 14 horses, and none of 32 Zebu cattle (Bos indicus), 18 paca (Cuniculus paca) and 20 spiny rats (Proechimys sp.). Contrary to common opinion, the results indicated a carrier state in the capybara. Diagnosis was based on morphology, behaviour in albino rats, and pathogenicity and host range in dome...
Studies on the prevalence of ringworm among horses in racing and breeding stables. A survey of 568 horses in training and 2,535 horses on breeding farms has shown 32 percent of the horses in training to be clinically affected while only 1.1 percent of breeding horses were affected with pathogenic dermatophytes. The majority of lesions on racing horses were located on the girth areas. Trichophyton equinum var. autotrophicum, M. canis and M. equinum were found to be restricted to racing horses only. M. gypseum occurred in racing, riding and breeding horses.
Four cases of Tyzzer’s disease in foals in England. A rodent pathogen, Bacillus piliformis, has been recognised as causing a rapidly fatal hepatitis in 4 foals in England. The disease in foals has been recognised in America since 1973. A clinico-pathological account of the 4 cases is given and the differential diagnosis discussed. The 4 foals' ages fell within a very narrow range (24-34 days). Some of the properties of this unusual intracellular pathogen are reviewed. For the first time in the equine the bacillus was seen in association with myocardial lesions. There are marked differences in the epidemiology of the disease in the mouse and in ...
Search for epizootic-like Venezuelan encephalitis virus at enzootic habitats in Guatemala during 1969-1971. Seventy-four strains of Venezuelan encephalitis (VE) virus recovered from sentinel hamsters or mosquitoes at enzootic habitats in Guatemala in the two years following the 1969 epidemic-equine epizootic were examined for ability to produce small plaques in Vero African green monkey kidney cell cultures, like isolates obtained during the epizootic. (a) One strain recovered from a sentinel hamster in late October 1969 at an enzootic habitat near the epicenter of the hemagglutination-inhibition (HI) and equine-virulence properties like epizootic virus; this strain retained its small plaque charact...
Serological studies and isolations of serotype hardjo and Leptospira biflexa strains from horses of Argentina. Three pathogenic leptosipras and 12 saprophytic Leptospira biflexa strains were isolated from 72 apparently normal horse kidneys collected at an abattoir in Argentina. Cross-agglutination reaction patterns of the pathogens showed that they were antigenically homologous with members of the Hebdomadis group. When one of the strains was compared to Hebdomadis serotypes in reciprocal agglutination-absorption tests, it was found to be serologically homologous to serotype hardjo. This is the first known report of an isolation of this serotype from horses. Serological tests were also carried out on r...
Isolation of mycoplasmas from the respiratory tract of horses in Australia. Mycoplasmas were isolated from two of 43 nasal swabs taken from live horses, and from one of 28 tracheal swabs taken from slaughtered horses. The slaughtered horse that yielded mycoplasmas had no gross pathological changes in the respiratory tract, but the nasal isolations were made from horses with rhinitis. The three mycoplasmas could be distinguished by cultural characteristics, and probably they represent three different species.
Isolation of mycoplasmas from the respiratory tract of horses in Australia. Mycoplasmas were isolated from two of 43 nasal swabs taken from live horses, and from one of 28 tracheal swabs taken from slaughtered horses. The slaughtered horse that yielded mycoplasmas had no gross pathological changes in the respiratory tract, but the nasal isolations were made from horses with rhinitis. The three mycoplasmas could be distinguished by cultural characteristics, and probably they represent three different species.
Ultrastructural observations on Ehrlichia equi organisms in equine granulocytes. The ultrastructure of the etiological agent of equine ehrlichiosis, Ehrlichia equi, was studied in equine peripheral leukocytes. The organisms occurred within membrane-lined cytoplasmic vacuoles of neutrophils and eosinophils. Ovoid, round, and rod-shaped profiles were observed. From 1 to 33 organisms were present in a thin-section profile of a cytoplasmic vacuole. Many cells contained multiple organism-containing vacuoles. The organisms had a cell wall and plasma membrane, and internally they consisted of electron-dense and lucid areas. A great variation in size was observed. The morphologica...
Gastrointestinal trichomonads in horses: occurrence and identification. A survey of horses for gastrointestinal trichomonads was conducted to determine the organism's role in equine diarrhea and to establish its proper identity and morphology. Trichomonads were found by cultural examination of feces of 101 (35%) of 289 apparently healthy horses. At necropsy, trichomonads were cultured from 11 (37%) of another 30 horses which showed no signs of diarrhea at the time of death. In 4 of the 11 horses, colonies of trichomonads numbered 30,000 to 150,000/ml of cecal fluid. Diarrhea was induced in 1 of 6 horses, with the fecal fluid containing 10,000 to 110,000 trichomona...
Occurrence of second and third instars of Gasterophilus intestinalis and Gasterophilus nasalis in stomachs of horses in Kentucky. The occurrence of 2nd and 3rd instars of Gasterophilus intestinalis and Gasterophilus nasalis was determined in 476 horses during the 22-year period from 1951 to 1973. Overall, G intestinalis infected 98.7% of the horses and averaged 168/horse; whereas G nasalis infected 80.7% of the horses and averaged 52/horse. Aggregate average total numbers for G intestinalis ranged from a low of 50 in September to a high of 229 in March, and for G nasalis, from a low of 14 in September to a high of 82 in February. Horses were infected by 2nd or 3rd instars of both species on a year-round basis. Differenti...
Studies in atypical Streptococcus equi. An atypical variety of Streptococcus equi is described. It was shown to be deficient in capsular material, to be very virulent for mice and to possess a cell-wall protein similar to the M-like protein of classical Str equi. Antiserum prepared against classical Str equi effectively opsonised the atypical strains, and induced the formation of long chains by these atypical strains. It is possible that this variant of Str equi can be used to overcome many of the current problems associated with the manufacture and use of strangles vaccines.
A serologic survey of pronghorns in Alberta and Saskatchewan, 1970-1972. To determine the exposure of free-ranging pronghorns (Antilocapra americana Ord) to selected pathogens, serum samples were obtained from 33 live-trapped animals from southwestern Saskatchewan in 1970, and from 26 and 51 animals from southeastern Alberta, in 1971 and 1972, respectively. Antibodies were found to the agents of parainfluenza 3, bovine virus diarrhea, eastern and western encephalomyelitis, infectious bovine rhinotracheitis and the chlamydial group. No serologic reactors were found to the agents of bluetongue, epizootic hemorrhagic disease, brucellosis, or leptospirosis (4 serotypes...
Pathological infection of thoroughbred horses with Gastrodiscus aegyptiacus. Contrary to common belief, Gastrodiscus aegyptiacus can be pathogenic to horses. History of cases of a particular stud, necropsy findings, diagnosis, and successful treatment with hexachlorophene and with dichlorvos are recorded. The presence of eggs can be established by a special flotation technique.
Experimentally induced infection of dogs, cats, and nonhuman primates with Ehrlichia equi, etiologic agent of equine ehrlichiosis. Dogs (German Shepherd Dogs and Beagles), cates, rhesus macaques (Macaca mulatta), and baboons (Papio anubis) were inoculated with Whrlichia equi, the etiologic agent of equine ehrlichiosis. Within 3 to 7 days after inoculation, morulae were observed in the eosinophils of cats, neurtrophils of macaques and baboons, and in both neutrophils and eosinophils of dogs. The severe disease produced in horses by this agent was not a feature of E equi infection in dogs, cats, macaques, and baboons. However, a susceptible horse, inoculated with the pooled blood of 2 infected macaques, developed severe cli...