Infections in horses encompass a range of diseases caused by various pathogens, including bacteria, viruses, fungi, and parasites. These infections can affect different systems within the horse, such as the respiratory, gastrointestinal, and integumentary systems, leading to a variety of clinical signs depending on the pathogen and the severity of the infection. Common infectious diseases in horses include equine influenza, strangles, and equine herpesvirus. Diagnosis often involves clinical examination, laboratory testing, and sometimes imaging, to identify the causative agent and assess the extent of the disease. Treatment strategies may include antimicrobial therapy, supportive care, and preventive measures such as vaccination and biosecurity practices. This page aggregates peer-reviewed research studies and scholarly articles that explore the pathogenesis, diagnosis, treatment, and prevention of infectious diseases in equine populations.
Clayton HM, Duncan JL.Following infection with 8000 Parascaris equorum eggs in two- to four-week-old foals reared under worm-free conditions a high percentage of the infective dose completed its tissue migration and returned to the small intestine. Patent infections were establisehd between 81 and 104 days after infection and high faecal egg counts were recorded. A group of six- to 12-month-old foals, which had been either reared under worm-free conditions or exposed to natural ascarid and strongyle infections on pasture, received a similar infection of 8000 P equorum eggs. Compared with the younger foals there was...
Roberts MC.Two young ponies had the prescrotal portion of their penises accidentally amputated during castration. They both developed ascending urinary tract infections over the next 4 weeks. One pony had a necrotising cystitis and pyelonephritis, the other improved markedly after a urethrostomy had been performed but was destroyed several months later.
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...
Drudge JH, Lyons ET, Tolliver SC.Critical tests were conducted on eight horses naturally infected with several species of large and small strongyles from population B. Tested were six benzimidazoles, including thiabendazole (2 lots) (44 mg/kg of body weight); mebendazole (8.8 mg/kg); cambendazole (two formulations) (20 mg/kg); fenbendazole (10 mg/kg); oxibendazole (10 mg/kg); and oxfendazole (10 mg/kg). All compounds were administered by stomach tube except one of the two cambendazole formulations which was an intraoral paste. Removal of large strongyles (when present), Strongylus vulgaris and Strongylus edentatus, was 100% b...
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.
Allen WE, Newcombe JR.The three groups of bacteria that cause endometritis in the mare are reviewed. The different methods of swabbing are assessed and the criteria which should be observed when developing a swabbing technique listed. The choice of speculum and swabs available are described.
Blue MG.Four cases of enterolith obstruction in horses aged from six to 14 years are reported. All four cases had symptoms of persistent low grade abdominal pain and anorexia with an absence of defaecation. Examination revealed reduced gut motility and accumulation of gas, but heart and respiratory rates, rectal temperatures and complete blood counts were all within normal limits. Enteroliths of varying sizes were removed from the region of the transverse colon in all four horses.
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...
Slauson DO, Lewis RM.Glomerulonephritis constitutes an important category of renal diseases in animals and has been recognized with increasing frequency in the last decade. We report here the comparative morphologic aspects of glomerulonephritis as a naturally occurring disease of animals. We briefly review the immunopathogenesis of glomerulonephritis. The morphology of renal lesions occurring in glomerulonephritis in dogs, cats, cattle, sheep, horses and swine has been reviewed with emphasis on the range and specificity of various glomerular lesions and on the comparison of lesions between various species. A dist...
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...
van der Molen EJ.The causes of neonatal mortality in foals were studied over a period of two years. The total number of foals studied was 121. Bacterial infection was found to be an important factor. Infection caused by A. equuli (1.6%) which previously was the most important one, has been superseded by E. coli infection (56%). E. coli infections particularly occur during the first weeks of life and, depending on the course of the disease, give rise to various pathological changes. Infections running an acute course are mainly marked by pathological changes of the lung and lymphoid organs. Infections running a...
Perryman LE, Buening GM, McGuire TC, Torbeck RL, Poppie MJ, Sale GE.Six young horses with combined immunodeficiency were given liver cells intravenously or intraperitoneally and thymuses subcutaneously from equine fetuses ranging from 68 to 110 days of gestational age. Three of four horses given cells from fetuses over 90 days of age developed lesions compatible with graft versus host reactions. One horse given cells from an 80-day fetus developed mitogen-responsive lymphocytes, synthesized immunoglobulins of the four major equine classes, and survived to 11.5 months of age. The sixth foal receiving cells from a 68-day fetus showed no discernable effects from ...
Mariotti F, Cuteri V, Takai S, Renzoni G, Pascucci L, Vitellozzi G.Two horses with Rhodococcus equi infection were examined post mortem by an immunohistochemical method (peroxidase-antiperoxidase; PAP) with a monoclonal antibody (Mab 10G5) to the 15-17 kDa antigen of R. equi. One of the horses was also examined bacteriologically, R. equi being isolated in culture. Immunolabelling with this Mab was marked and widespread. On the other hand, the immunohistochemical reactivity of infected macrophages with a polyclonal antibody specific for lysozyme was slight. Thus, Mab 10G5 would appear to be a useful diagnostic reagent in R. equi infection, with or without cult...
McChesney AE.Since the advent of cell culture techniques, numerous viruses have been shown to be related to respiratory diseases in horses. Although the viruses differ in many ways, they cause disease with some common characteristics. This report is a summary of some of the available material from written sources and from personal observations. It is intended to help explain some of the changes observed in viral-induced respiratory disease.
Roberts MC, Seawright AA, Ng JC.Phenylmercuric acetate (PMA) was administered orally to a horse over a period of 27 weeks (190 days) at a dose rate of 0.4 mg Hg/kg per day. The effects produced were consistent with those of chronic inorganic mercury intoxication. The clinical features included masseter muscle atrophy, difficulty in prehension and mastication, malodorous breath, reduced appetite and weight loss, and reflected significant pathological changes involving the buccal, mandibular and dental tissues. Renal dysfunction was evident terminally and there was degeration and necrosis of the proximal tubular epithelium. Ne...
Boorman S, Boone L, Weatherall K, Caldwell F.A 7-year-old American Quarter Horse gelding was referred to the JT Vaughan Large Animal Teaching Hospital at Auburn University, College of Veterinary Medicine, for an investigation of a recurrent swelling of the nasofrontal region. Computed tomography examination of the skull was most consistent with a sequestrum of the left nasofrontal suture with associated focal osteomyelitis and left conchofrontal sinusitis. Surgery to remove the sequestrum, debride the devitalized bone, and flush the left conchofrontal sinus was performed. A microbial culture was obtained at the time of surgery, which yie...
Koblik PD, Lofstedt J, Jakowski RM, Johnson KL.Indium 111-labeled autologous leukocytes were used to image an abdominal abscess in a horse with a palpable abdominal mass and history of Streptococcus equi infection. A focal area of radioactivity was identified in the location corresponding to the abscess. Imaging of this focal uptake was optimal 48 hours after injection. Similar scans obtained in 2 clinically normal horses revealed no evidence of focal radioactivity in this region. The cell labeling procedure gave acceptable labeling efficiency (87.5%) but an excessive number of damaged WBC, resulting in persistent lung radioactivity on all...
Kim L, Morley PS, McCluskey BJ, Mumford EL, Swenson SL, Salman MD.To report clinical and serologic findings in horses with oral vesicular lesions that were consistent with vesicular stomatitis (VS) but apparently were not associated with VS virus (VSV) infection. Methods: Serial case study. Methods: 8 horses. Methods: Horses were quarantined after appearance of oral lesions typical of VS. Severity of clinical signs was scored every 2 to 5 days for 3 months. Serum samples were tested for antibodies by use of competitive ELISA (cELISA), capture ELISA for IgM, serum neutralization, and complement fixation (CF). Virus isolation was attempted from swab specimens ...
Ferraro CC, Kloss AB, De Souza DF, Deconto I, Biondo AW, Molento MB.The carthorses are used as an alternative for people of low income for collecting recyclable material. However, these horses are managed without proper assistance, suffering several problems, among them the parasites. In this study we used 41 animals, their body condition score and other parameters were analyzed and parasite egg count was performed from fecal samples. It was determined the absence of eggs on 12% and parasite infection in 88%. Strongylids were found in all contaminated animals, often associated with oocysts or Parascaris equorum. This condition may be due to poor nutritional ma...