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Topic:Infection
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.
Seasonal changes in pasture infectivity by equine cyathostomes in north central Florida. ALTHOUGH the seasonal transmission of equine cyathostomes is well documented in cool climates (Ogbourne 1978),
less is known about their transmission in warm climates.
Australian studies have suggested that these parasites do not
survive well during the long, hot summers of the humid
subtropics (English 1979a.b). Development of egg to third
stage larva (L3) was rapid during the summer but the
percentage of larvae that survived to ascend herbage was very
low. In contrast, larvae survived for longer periods during the
cooler months and the highest L3 populations were observed
during spr...
Observations of tabanid feeding on mares and foals. The occurrence of tabanid feeding between mares and foals was observed. When mares and foals were observed freely moving within a pasture situation, foals had 2.43% (4 flies in 77 observations vs 297 flies in 139 observations) of the tabanid feeding occurrences of the mares. This difference in tabanid burden varied due to herd size, herd location, and tabanid species. Lower tabanid burden of foals was indicated as a practical protective mechanism against pathogenic agents mechanically transmitted by tabanids, such as equine infectious anemia virus.
Larval cyathostomiasis (immature trichonema-induced enteropathy): a report of 15 clinical cases. Clinical and laboratory findings are recorded from a series of 15 cases (aged one to 16 years) of sudden-onset chronic diarrhoea with weight loss, progressing in many cases to emaciation and death, associated with the emergence of fourth stage cyathostome (trichoneme) larvae in large numbers through the colonic and caecal mucosae. Apart from a single incident in mid-October, disease only occurred in winter and spring (January to May). Characteristic features included hypoalbuminaemia, increased alpha and beta plasma globulin levels and neutrophilia without left shift. Faecal egg counts were fr...
Fiberoptic gastroduodenoscopy in the horse. A method of fiberoptic gastroduodenoscopy and biopsy was developed for use in large horses. A 275 cm X 13.5 mm fiberendoscope was used to examine the stomach and proximal portion of the duodenum. Food was withheld for 24 to 48 hours before examination. In more than 50 horses, gastric and duodenal structures were easily visualized. A variety of lesions was detected, including parasitic lesions, gastric ulcers, gastric neoplasia, and pyloric stenosis. Mucosal biopsy specimens were obtained in selected cases.
Prevalence and epidemiology of the major gastrointestinal parasites of horses in Perth, Western Australia. A survey was conducted on the prevalence of the major gastrointestinal parasites in 140 horses necropsied in Perth, Western Australia, during 1979 to 1982. Adult Strongylus vulgaris were found in 22.5 per cent of horses and verminous arteritis in 62.9 per cent. The peak worm prevalence was in November to January (summer). S edentatus had a similar prevalence and seasonality but S equinus was not found in this survey. Draschia megastoma and Habronema muscae were found in 66.2 per cent and 35.3 per cent of horses respectively. Infection is probably acquired in summer when 8 per cent of the Musca...
Prospective study of progeny of inapparent equine carriers of equine infectious anemia virus. Progeny of a band of horses, positive by the agar-gel immunodiffusion (AGID) test for equine infectious anemia (EIA) antibody, were observed through their weaning over a 4-year period. Sentinels (AGID test-negative) were allowed to mingle with EIA-infected mares and their foals in pasture situations in an area with high populations of potential vectors. Of 27 adult sentinels, 8 (30%) seroconverted in annual rates ranging from 0% to 75%. In contrast, only 2 of 31 (6%) foals weaned became infected. Difference in infection rates between adult sentinels and foals was significant (chi 2, P less tha...
Integrated control of Strongylus vulgaris infection in horses using ivermectin. An attempt was made to control or eliminate Strongylus vulgaris from a closed group of three horses at pasture near Perth, Western Australia, by dosing with ivermectin on four occasions during the time of year when it was believed that environmental conditions would eliminate all the non-parasitic stages of that species. At necropsy, five months after the last dose of anthelmintic and after continually grazing the same pastures, no S vulgaris or arterial lesions were found in those horses and S edentatus, Draschia megastoma and Habronema species were also almost completely eliminated.
Bilateral laryngeal paralysis in the horse. Four two-year-old Thoroughbreds suffered an acute gastrointestinal illness shortly after dosing with mineral oil which was thought to have been contaminated with an organophosphate compound. Three weeks later all four were noted to be dyspnoeic and endoscopic examination showed that they had developed bilateral laryngeal paralysis. Two of the horses died during severe bouts of dyspnoea six and eight months later and the third was killed shortly thereafter. Examination of the left and right recurrent laryngeal nerves from these horses showed a severe loss of myelinated fibres distally, especial...
[Mechanism of distribution of Strongyloidea larvae among ungulate animals at pasture]. The problem of dissimilation of larvae of strongylates of ruminants in pasture biocoenosis is discussed. A new form of their migration in horizontal direction on the basis of negative geotaxis is suggested. As a result of alternation of vertical migration of larvae on the tilting leaves of the grass and their subsequent washing off with rain or dew down on the ground proceeds their distribution on the pasture. The description of corresponding experiments is given.
Epidemiological approach to the control of horse strongyles. An investigation of the spring rise in strongyle egg output of grazing horses on two commercial horse farms in northern USA in 1981 and 1982 revealed two distinct spring and summer rises in faecal egg counts, with peaks in May and August/September. There was a marked rise in the concentration of infective larvae on pasture two to four weeks after the peaks in egg output, so that grazing horses were at serious risk from June onwards and pasture larval counts on one farm did not fall to low levels until June of the following year. The spring and summer rises in faecal egg counts appeared to be s...
Chronic eosinophilic pancreatitis and ulcerative colitis in a horse. A generalized debilitating disease in a horse was believed to be related to hypersensitivity to migrating strongyle larvae. The clinical signs included weight loss, diarrhea, and ulcers on all 4 coronary bands. The mare's condition deteriorated rapidly, so the mare was euthanatized and necropsied. The major histopathologic findings were chronic multifocal eosinophilic pancreatitis, hepatic portal fibrosis, biliary hyperplasia, and chronic ulcerative eosinophilic colitis. This case was similar to previously reported cases of chronic eosinophilic gastroenteritis in horses. Although the etiologic...
Cryptosporidiosis in two foals. Cryptosporidium oocysts were identified by phase contrast microscopy on smears from flotations of greenish-yellow pasty feces obtained from two foals. One foal, a one week old Percheron was recumbent, anorectic and lethargic, believed to be the result of a septicemia of undetermined etiology. Despite therapy and nursing care the animal died. Using light and electron microscopy, numerous stages of Cryptosporidium sp. were seen protruding from the surface of epithelial cells of intestinal villi. The other foal, a six week old Arabian had a mild diarrhea. The diarrhea and passage of oocysts event...
Intensive care of the neonatal foal. The basic concepts of diagnosis and treatment in the abnormal neonatal foal are presented. Methods of restraint, sedation, and general nursing care are discussed, as well as more specific techniques of respiratory and circulatory system support.
Common plasmid encoding resistance to ampicillin, chloramphenicol, gentamicin, and trimethoprim-sulfadiazine in two serotypes of Salmonella isolated during an outbreak of equine salmonellosis. An outbreak of equine salmonellosis occurred at the Veterinary Medical Teaching Hospital, University of California, Davis, between June 1981 and March 1982. Forty-four horses were infected with Salmonella saint-paul, a serotype rarely isolated from animals at the university before the outbreak. Unlike the isolates of S saint-paul obtained at the beginning of the outbreak, almost all strains isolated near the end were resistant to ampicillin, cephalothin, chloramphenicol, gentamicin, kanamycin, sulfadiazine, trimethoprim, and trimethoprim-sulfadiazine. A conjugal-resistance plasmid (R-plasmid) ...
Two techniques for detection of antibodies against Corynebacterium (Rhodococcus) equi in horse sera. Two techniques were developed to detect antibodies against the exosubstance of C. equi called equi-factor. In the first technique serum samples are tested against native equi-factor produced by the growth of C. equi on agar medium. A positive result is manifested by the development of precipitation lines. The second test is based on neutralization of prepurified equi-factor by antibody, resulting in the inhibition of its hemolytic synergism with staphylococcal beta toxin. Sera (125 samples) from horses of different ages, kept in localities with a history of C. equi infections, were examined. T...
Prevention and control of infection. Foal septicemia is a major cause of neonatal morbidity and mortality. In order to improve success rates, earlier diagnosis and treatment are essential. This article stresses methods to prevent and treat infections in the compromised equine neonate.
Phycomycosis caused by Basidiobolus haptosporus in two horses. Basidiobolus haptosporus was isolated from a horse with a rapidly progressive ulcerative lesion of the ventral midline. The pathologic findings of an irregular line of yellow material composed of hyphae, eosinophils, and granulomatous inflammation between the superficial edematous tissue and the underlying muscle, and hyphae in tissue sections intimately surrounded by granular eosinophilic cuffs were considered diagnostic for this and one other case diagnosed retrospectively. Both horses were successfully treated by surgery and potassium iodide.
Hematology, blood typing, and immunology of the neonatal foal. Hematologic parameters change during the first 10 days of life. Erythrocytes increase in number but decrease in size and hemoglobin concentration. The PCV, hemoglobin, and platelet count also decrease. Total blood and plasma volume and, to lesser extent, erythrocyte volume decrease. Normal neonatal foals may have immature neutrophils (up to 5 per cent bands), and their early rapid rise in neutrophil numbers may be accompanied by a lymphopenia. Monocytes, eosinophils, and basophils are all absent or low initially. Infectious processes can cause rapid and variable changes in the leukogram. Howev...
Parasites in lungs of dead equids in Kentucky: emphasis on Dictyocaulus arnfieldi. Prevalence of natural infections of parasites from the lungs of 488 dead Thoroughbreds in Kentucky was investigated. The horses varied from 1 to 32 years of age; 419 horses were from 215 farms and 69 horses were from 68 individual sources for which a specific farm was not identified. Examinations of the lungs were made from Mar 1, 1983 through Feb 29, 1984. Dictyocaulus arnfieldi was recovered from 56 (11%) of the horses. Other parasites found were larvae of Parascaris equorum in 37 (8%) and of Habronema/Draschia in 67 (14%) of the horses. The possible effect of ivermectin treatment on the pre...
Neurologic diseases. The responses of apparently healthy newborn foals to neurologic testing differ significantly from those of adult horses. These responses and the diagnostic techniques pertinent to neurologic problems are reviewed as a basis for evaluation of the compromised neonatal foal. The more frequently encountered neurologic diseases are discussed in a problem-oriented format. These clinical problems include behavioral abnormalities, convulsions, changes in consciousness, blindness, ataxia without loss of strength, ataxia with weakness and paralysis, and the floppy foal.
Lungworms (Dictyocaulus arnfieldi): prevalence in live equids in Kentucky. Prevalence of natural infections of the lungworm, Dictyocaulus arnfieldi, was investigated in Kentucky in 5,437 live equids (horses, ponies, and asses) on 91 farms by examination of fecal samples over a 15-month-period from January 28, 1983 to April 19, 1984. For the 91 farms investigated, asses only were examined on 1 farm; for the other 90 farms, examinations were made of horses on all of them, of ponies on 4 farms, and of asses on 9 farms. Larvae of D arnfieldi were found in fecal samples of 112 (2%) of 5,379 horses on the 90 farms of which 38% had greater than or equal to 1 infected animal...
Respiratory problems in foals. Despite major advances in our knowledge and ability to treat respiratory diseases in neonatal foals, neonatal respiratory medicine is still in its infancy. It is hoped that this article may serve as a guideline for diagnosis and treatment. Specific antibiotic regimens and emergency procedures are covered in other articles in this symposium. Because management factors play a critical role in the pathogenesis of respiratory disease, education of clients as to their importance would help both prophylactically and therapeutically. The necessity of very careful monitoring of neonates, which is crit...
Comparison of peripheral blood and uterine-derived polymorphonuclear leukocytes from mares resistant and susceptible to chronic endometritis: chemotactic and cell elastimetry analysis. The functional competence of peripheral blood and uterine-derived polymorphonuclear leukocytes (PMN) from 12 mares were analyzed for chemotactic responsiveness using a chemotactic chamber (filter) assay and for deformability by cell elastimetry analysis. Peripheral blood PMN obtained from control mares and from 8 mares experimentally inoculated via the uterus with 1 x 10(9) Streptococcus zooepidemicus had similar normal chemotactic responsiveness and were highly deformable before and at 12 hours after inoculation. Uterine PMN obtained 12 hours after uterine inoculation with S zooepidemicus fro...
Identification and characteristics of staphylococci isolated from lesions and normal skin of horses. One hundred and twenty eight strains of Staphylococcus from lesions, mostly of the skin, in horses were identified and compared with 29 strains isolated from the healthy skin. The pathogenic species Staphylococcus aureus, S. intermedius and S. hyicus were found almost exclusively in lesions. Other species such as S. xylosus and S. sciuri were more frequently found on the healthy skin than in lesions. The S. aureus strains formed a very heterogeneous collection. Many of these strains were staphylokinase positive and rapidly coagulated bovine plasma. Such strains are rarely found in other animal...
Aspects of pharmacology in the neonatal foal. Other therapeutic agents used in foals for specific diseases are discussed elsewhere. The marked effect of species, age, and degree of maturity on drug metabolism in the neonate reinforces the danger of interspecies extrapolation of pharmacology, the need for information specific for the foal, and the necessity for monitoring drug levels in the individual. Suggested antimicrobial doses are listed in Tables 3, 4, and 6. Recommended doses of anticonvulsants and sedatives are listed in Table 8 and in the article "Intensive Care of the Neonatal Foal." The following are recommendations for drug the...
