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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.
Immunologic diseases. Selected equine cutaneous diseases for which there is strong evidence of an immunological aetiology are discussed in this section. The reactive disorders of urticaria, Culicoides hypersensitivity, erythema multiforme, drug eruptions and systemic granulomatous disease are included. The autoimmune diseases of the horse with cutaneous manifestations (pemphigus foliaceus, pemphigus vulgaris, bullous pemphigoid and cutaneous lupus erythematosus) are discussed. The clinical signs and diagnostic features of these immunologically induced equine dermatoses are defined, and the challenges in making a de...
Nodular diseases. The development of a nodule is a fairly common reaction pattern in the skin and subcutaneous tissues of the horse. In many such nodules, the inciting aetiologic agent or antigen is unknown, but in some equine cases there is significant evidence for insect bite origin. The pathogenesis of some equine nodular diseases appears to involve marked collagen degeneration which varies from hyalinization to lysis and can become mineralized. The exact role the lytic collagen has in the pathogenesis of these lesions is still unknown. Vascular changes may be present in some entities. Other nodules may be c...
Unilateral nondisseminated actinomycosis of the hydrocele wall: a case report of actinomycosis in the urogenital tract. Actinomycosis of the urogenital tract is rare and predominantly an infectious disease of horses, cattle, swine, and humans. This case report describes isolated actinomycosis of the hydrocele wall presenting as an inflamed right-sighted hydrocele.
Secondary structure model for the ITS-2 precursor rRNA of strongyloid nematodes of equids: implications for phylogenetic inference. In order to maximise the positional homology in the primary sequence alignment of the second internal transcribed spacer for 30 species of equine strongyloid nematodes, the secondary structures of the precursor ribosomal RNA were predicted using an approach combining an energy minimisation method and comparative sequence analysis. The results indicated that a common secondary structure model of the second internal transcribed spacer of these nematodes was maintained despite significant interspecific differences (2-56%) in primary sequences. The secondary structure model was then used to refine...
[Equine Rhodococcus equi pneumonia: first report in Israel and its significance for man]. Rhodococcus equi is an important pathogen in young horses. In recent years it has been increasingly recognized as an opportunistic infectious agent in patients with immune deficiency. The increase in recognized cases may be related to the increased prevalence of AIDS. However, more cases may have been recognized lately due to increased awareness of the pathogenicity of this bacterium. Based on medical reports, there appears to be an association between Rhodococcus equi infections and exposure to animals, horses in particular. During the past year, 2 cases of rhodococcus pneumonia were diagnose...
Scintigraphic detection of equine orthopedic infection using Tc-HMPAO labeled leukocytes in 14 horses. The aim of this study was to evaluate the diagnostic value of 99mTc-HMPAO leukocyte scintigraphy (LS) by means of a retrospective review of its use in 14 horses that were evaluated for orthopedic infection as a cause of lameness. A total of 17 LS exams were performed in 14 horses. LS studies were positive in 10 of 14 horses. A bacterial infection was confirmed with cytology or culture in 9 of 10 positive horses. Negative LS studies occurred in 4 of 14 horses. Necropsy confirmed the lack of infection in 2 of the 4 horses. Other clinical data and a favorable clinical outcome supported a negative...
Characterization of Escherichia coli isolated from adult horses with and without enteritis. In the present study E. coli strains isolated from the faeces of ten horses with diarrhoea and 14 horses without diarrhoea were characterized. All horses were culture negative for Salmonella species. Nine colonies of E. coli from each faecal sample were picked at random and a DNA fingerprint was made by means of a polymerase chain reaction (PCR) using Enterobacterial Repetitive Intergenic Consensus (ERIC) primers. The number of E. coli genotypes did not differ significantly between horses with and without diarrhoea. In addition, all E. coli strains with different DNA fingerprints were tested b...
Transmission of Ehrlichia risticii, the agent of Potomac horse fever, using naturally infected aquatic insects and helminth vectors: preliminary report. Ehrlichia risticii, the agent of Potomac horse fever (PHF), has been recently detected in trematode stages found in snail secretions and in aquatic insects. Based on these findings, horses could conceivably be exposed to E. risticii by skin penetration with infected cercariae, by ingestion of infected cercariae in water or via metacercariae in a second intermediate host, such as an aquatic insect. In order to test this hypothesis, horses were challenged with infectious snail secretions and aquatic insects collected from a PHF endemic region in northern California. Two horses stood with their f...
Influence of bacitracin on microbial functions in the gastrointestinal tract of horses. This study investigated the influence of zinc bacitracin on the intestinal flora of horses. The functionally active intestinal flora was examined in 6 horses during treatment with zinc bacitracin. Utilising gas chromatography, spectrophotometry, gel electrophoresis and paper chromatography, samples were analysed on biochemical markers reflecting the action of parts of the intestinal flora. The following 5 flora-related functions were studied in faecal samples and intestinal samples from different sections of the hindgut: conversion of cholesterol to coprostanol and of bilirubin to urobilinogen...
Pharmacokinetics of erythromycin estolate and erythromycin phosphate after intragastric administration to healthy foals. To determine pharmacokinetics and plasma concentrations of erythromycin and related compounds after intragastric administration of erythromycin phosphate and erythromycin estolate to healthy foals. Methods: 11 healthy 2- to 6-month-old foals. Methods: Food was withheld from foals overnight before intragastric administration of erythromycin estolate (25 mg/kg of body weight; n = 8) and erythromycin phosphate (25 mg/kg; 7). Four foals received both drugs with 2 weeks between treatments. Plasma erythromycin concentrations were determined at various times after drug administration by use of high-p...
Determination of the activity of ponazuril against Sarcocystis neurona in cell cultures. The present study examined the efficacy of ponazuril in inhibiting merozoite production of Sarcocystis neurona in cell cultures. Ponazuril inhibited merozoite production by more that 90% in cultures of S. neurona treated with 1.0 microg/ml ponazuril and greater than 95% inhibition of merozoite production was observed when infected cultures were treated with 5.0 microg/ml ponazuril. Ponazuril may have promise as a therapeutic agent in the treatment of S. neurona induced equine protozoal myeloencephalitis (EPM) in horses.
Inoculation of Sarcocystis neurona merozoites into the central nervous system of horses. Equine protozoal myeloencephalitis (EPM) is a neurologic syndrome in horses from the Americas and is usually caused by infection with the apicomplexan parasite, Sarcocystis neurona. A horse model of EPM is needed to test the efficacy of chemotherapeutic agents and potential vaccines. Five horses that were negative for antibodies to S. neurona in their serum and cerebrospinal fluid (CSF) were injected in the subarachnoid space with living merozoites of the SN2 isolate of S. neurona. None of the horses developed clinical disease or died over a 132-day observation period. All five horses develope...
Equine herpesvirus 1 (EHV-1) glycoprotein D DNA inoculation in horses with pre-existing EHV-1/EHV-4 antibody. We have shown previously that equine herpesvirus 1 (EHV-1) glycoprotein D (gD) DNA elicited protective immune responses against EHV-1 challenge in murine respiratory and abortion models of EHV-1 disease. In this study, 20 horses, all with pre-existing antibody to EHV-4 and two with pre-existing antibody to EHV-1, were inoculated intramuscularly with three doses each of 50, 200 or 500microg EHV-1 gD DNA or with 500microg vector DNA. In 8 of 15 horses, inoculation with EHV-1 gD DNA led to elevated gD-specific antibody and nine horses exhibited increased virus neutralising (VN) antibody titres co...
Neospora hughesi: experimental infections in mice, gerbils, and dogs. Neospora hughesi is a recently described cause of equine protozoal myeloencephalitis (EPM). A rodent model for pathogenicity would facilitate development of therapies to be used in horses. In the present study, we examined the susceptibility of BALB/c gamma-interferon gene knockout (gamma-INFKO), BALB/c, CD-1, and C57BL/6 strains of mice and gerbils to infection with tachyzoites of the Nh-A1 strain of N. hughesi isolated from a horse from AL, USA. Only the gamma-IFNKO mice developed severe clinical disease following infection with N. hughesi and died 19-25 days after infection and exhibited se...
Detection of biological threat agents by immunomagnetic microsphere-based solid phase fluorogenic- and electro-chemiluminescence. This article reviews the recent development of two solid-phase chemiluminescence-based techniques, fluorogenic-chemiluminescence (FCL) and electro-chemiluminescence (ECL) for detection of biological threat agents. Both techniques entail a labeled sandwich immunoassay. The objectives of this work are to develop advanced techniques for sensitive and effective detection of a target analyte, particularly in cases where the analysis includes complex samples containing multiple contaminating factors. Other important considerations in developing such detection techniques include the ease of use, the ...
Concentrations of cadmium, lead and zinc in livestock feed and organs around a metal production centre in eastern Kazakhstan. This paper presents results of analysis of animal feed and meat (cattle, horse and sheep) products from a metal processing region (Oskemen) in east Kazakhstan. Samples were collected from a range of districts of differing distances from the main source of anthropogenic pollution and with differing underlying metal-containing geologies. Analyses for cadmium, lead and zinc revealed high concentrations in many feed and meat samples. Horse (an important food animal) samples had higher levels of contamination than cattle, which were higher than sheep. For example, mean cadmium concentrations in hor...
Prevalence of selected species of internal parasites in equids at necropsy in central Kentucky (1995-1999). A survey to determine current prevalence of several species of endoparasites in equids (n=350) at necropsy was conducted at the Livestock Disease Diagnostic Center in central Kentucky (1995-1999). Thelazia lacrymalis were found in 42% of the 1- to 4-year olds (n=132), which was the only age group examined for these parasites. Five- to 30-year olds (n=157), examined for Onchocerca spp. worms/lesions, had a prevalence of 24%. In > or =1-year olds (n=324), the infection rate for Gasterophilus intestinalis was 12% for second instars and 14% for third instars and for Gasterophilus nasalis was 2%...
An outbreak of type C botulism in 12 horses and a mule. A USDA Early Response Team investigated deaths of several horses and a mule in northern Arizona at the request of local animal health officials. Thirteen animals (12 horses and 1 mule) housed at 5 facilities in a 7.4 square mile area died between August 1998 and January 1999. Clinical signs consisted of muscular weakness that rapidly progressed to lateral recumbency. Ten animals had paresis of the tongue, throat, or lips. Affected animals appeared alert and were interested in eating and drinking, even while recumbent. All 13 animals were euthanatized. Clostridium botulinum type C was isolated ...
Pathogenicity of Rhodococcus equi expressing a virulence-associated 20 kDa protein (VapB) in foals. Rhodococcus equi strains of intermediate virulence (IMV) for mice possess a 20kDa protein designated Virulence Associated Protein B (VapB) and a virulence plasmid of 79-100kb, and can be recovered from the submaxillary lymph nodes of pigs. The pathogenicity of such R. equi strains for foals is unknown. In this study, two foals, 42 and 43 days of age, were infected intratracheally with 10(6) and 10(9) cells of R. equi IMV strain A5, respectively. The foal infected with 10(9) cells of strain A5 became clinically ill, with the onset of illness (pyrexia and depression) occurring 21 days after inoc...
[Sensitivity of bovine and equine streptococci to beta-lactam antibiotics (benzylpenicillin, ampicillin, oxacillin, cefotaxime) in the agar diffusion and E-test]. 368 streptococcal strains from udder secretions of cattle (Sc. agalactiae, Sc. dysgalactiae, Sc. uberis) and 191 streptococcal isolates from horse specimens (Sc. equi ssp. zooepidemicus, Sc. equi ssp. equi) originating from different agricultural regions in Germany (Lower Saxony, in particular the region of Weser-Ems, Bavaria, Altmark) were investigated for their sensitivity to 4 beta-lactam antibiotics (benzylpenicillin, ampicillin, oxacillin, cefotaxime). Two different test methods were applied: the agar diffusion test for determination of the diameter of the zone of inhibition and the E-tes...
The acute phase protein serum amyloid A (SAA) as an inflammatory marker in equine influenza virus infection. The acute phase protein serum amyloid A (SAA) has proven potentially useful as an inflammatory marker in the horse, but the knowledge of SAA responses in viral diseases is limited. The aim of this study was to evaluate SAA as a marker for acute equine influenza A2 (H3N8) virus infection. This is a highly contagious, serious condition that inflicts suffering on affected horses and predisposes them to secondary bacterial infections and impaired performance. Seventy horses, suffering from equine influenza, as verified by clinical signs and seroconversion, were sampled in the acute (the first 48 h...
Cecal amputation within the right ventral colon for surgical treatment of nonreducible cecocolic intussusception in 8 horses. To report a surgical technique for treatment of nonreducible cecocolic intussusception and outcome in 8 horses. Methods: Retrospective study. Methods: Eight horses with nonreducible cecocolic intussusception treated by cecal amputation through a right ventral colotomy. Methods: Data were obtained from medical records and telephone conversations by using a standardized questionnaire. The large colon was exteriorized and, if necessary, evacuated of its contents through a pelvic flexure enterotomy. A second colotomy was made on the ventral surface of the right ventral colon (RVC) centered over or...
Utilisation of bacteriophage display libraries to identify peptide sequences recognised by equine herpesvirus type 1 specific equine sera. Three filamentous phage random peptide display libraries were used in biopanning experiments with purified IgG from the serum of a gnotobiotic foal infected with equine herpesvirus-1 (EHV-1) to enrich for epitopes binding to anti-EHV-1 antibodies. The sequences of the amino acids displayed were aligned with protein sequences of EHV-1, thereby identifying a number of potential antibody binding regions. Presumptive epitopes were identified within the proteins encoded by genes 7 (DNA helicase/primase complex protein), 11 (tegument protein), 16 (glycoprotein C), 41 (integral membrane protein), 70 ...
Infection of aquatic insects with trematode metacercariae carrying Ehrlichia risticii, the cause of Potomac horse fever. We provide evidence of Ehrlichia risticii Holland, the agent of Potomac horse fever, in trematode stages found in aquatic insects collected from a pasture stream in northern California, using nested polymerase chain reaction (PCR) amplification and sequence analyses of the 16S rRNA, 51 kDa major antigen and groEL heat shock protein genes. E. risticii was detected in metacercariae found in the immatures and adults of the following insects: caddisflies (Trichoptera), mayflies (Ephemeroptera), damselflies (Odonata, Zygoptera), dragonflies (Odonata, Anisoptera), and stoneflies (Plecoptera). The pr...
Association of disease with isolation and virulence of Rhodococcus equi from farm soil and foals with pneumonia. To determine whether isolation and virulence of Rhodococcus equi from soil and infected foals are associated with clinical disease. Methods: Cross-sectional and case-control study. Methods: R equi isolates from 50 foals with pneumonia and soil samples from 33 farms with and 33 farms without a history of R equi infection (affected and control, respectively). Methods: R equi was selectively isolated from soil samples. Soil and clinical isolates were evaluated for virulence-associated protein antigen plasmids (VapA-P) and resistance to the beta-lactam antibiotics penicillin G and cephalothin. Mic...
Treatment of supraspinous bursitis by use of debridement in standing horses: 10 cases (1968-1999). To evaluate efficacy of debridement for treatment of supraspinous bursitis in horses and to evaluate the outcome. Methods: Retrospective study. Methods: 10 horses with clinical signs of supraspinous bursitis. Methods: Medical records were reviewed for signalment, anamnesis, results of physical and radiographic examination, microbial culture results of supraspinous bursa tissue or exudate, Brucella abortus titers, type of antimicrobial and anti-inflammatory therapies, surgical technique, complications of the surgical procedure, and findings on histologic examination of excised nuchal ligament a...
Fecal shedding of Salmonella spp by horses in the United States during 1998 and 1999 and detection of Salmonella spp in grain and concentrate sources on equine operations. To estimate prevalence of fecal shedding of Salmonella spp among horses in the US horse population and prevalence of Salmonella spp in grain or other concentrate used as horse feed on equine operations in the United States. Methods: Cross-sectional survey. Methods: Horses on 972 operations in 28 states. Methods: Fecal samples were collected from horses resident at each operation. Only a single sample was collected from any individual horse; number of horses from which samples were collected on each operation was determined on the basis of number of horses on the operation. A single sample of g...
Halicephalobus gingivalis encephalomyelitis in a horse. An 8-year-old, Arabian mare presented with acute progressive ataxia and a firm swelling over the right mandible. Radiographs revealed multiple radiolucent areas on the mandibles. The mare's neurological signs progressed, she was consequently euthanized. Postmortem examination revealed mandibular granulomatous reactions and meningoencephalitis due to the nematode Halicephalobus gingivalis.
Survival of Clostridium difficile and its toxins in equine feces: implications for diagnostic test selection and interpretation. Although Clostridium difficile is recognized as a cause of enterocolitis in horses and humans, there has been little work published regarding the lability of C. difficile and its toxins in feces. A significant decrease in recovery of C. difficile from inoculated equine fecal samples occurred during storage. Recovery after storage in air at 4 degrees C decreased from 76% (37/49) after 24 hours to 67% (33/49) at 48 hours and 29% (14/ 49) after 72 hours. In contrast to aerobic storage, 25 of 26 samples stored anaerobically at 4 degrees C yielded growth of C. difficile for 30 days, whereas the org...
