Pneumonia in horses is a respiratory condition characterized by inflammation of the lungs, often caused by bacterial, viral, or fungal infections. It can affect horses of all ages, though young and immunocompromised animals are more susceptible. Clinical signs of pneumonia in horses may include coughing, nasal discharge, fever, and labored breathing. Diagnosis typically involves a combination of clinical examination, imaging techniques such as radiography or ultrasonography, and laboratory tests including blood work and microbial cultures. Treatment strategies vary depending on the underlying cause and may involve antimicrobial therapy, supportive care, and environmental management. This page compiles peer-reviewed research studies and scholarly articles that explore the etiology, pathophysiology, diagnosis, and treatment of pneumonia in equine populations.
Venturini C, Bowring B, Partridge SR, Ben Zakour NL, Fajardo-Lubian A, Lopez Ayala A, Qin J, Totsika M, van Galen G, Norris J, Iredell J.The global epidemiology of multidrug resistant Klebsiella pneumoniae, a serious threat to both animal and human health, is dominated by the spread of pathogenic clones, each separately evolving via acquisition of transferable antibiotic resistance or niche-specific virulence determinants. In horses, K. pneumoniae infection can lead to severe respiratory illness. Here, we characterized multiple isolates recovered from bronchial aspirates of a mare with pneumonia refractory to antibiotics. First, we used a combination of standard microbiology, bacteriophage cross-susceptibility and antibiotic re...
Rahman A, Uzal FA, Hassebroek AM, Carvallo FR.Pneumonia is a significant disease of horses. Although pneumonia has traditionally been studied in racehorses, little information is available for non-racing horses. Non-racing horses that died with pulmonary lesions ( = 156) were available from cases submitted for autopsy from January 2015 to June 2020. Bronchopneumonia (35%), interstitial pneumonia (29%), embolic pneumonia (21%), granulomatous pneumonia (13%), and pleuritis (2%) were observed in the examined horses. Seventy-four horses died or were euthanized because of pulmonary diseases, and 82 horses died or were euthanized because of...
Narváez SÁ, Fernández I, Patel NV, Sánchez S. is an important veterinary pathogen that takes the lives of many foals every year. With the emergence and spread of MDR to current antimicrobial treatment, new tools that can provide a fast and accurate diagnosis of the disease and antimicrobial resistance profile are needed. Here, we have developed and analytically validated a multiplex qPCR for the simultaneous detection of and related macrolide resistance genes in equine respiratory samples. The three sets of oligos designed in this study to identify housekeeping gene and macrolide resistance genes (46) and (51) showed high analytic se...
Cohen ND, Flores-Ahlschewde P, Gonzales GM, Kahn SK, da Silveira BP, Bray JM, King EE, Blair CC, Bordin AI.Diagnostic accuracy of real-time, quantitative PCR (qPCR) assays to quantify virulent Rhodococcus equi using rectal swab samples has not been systematically evaluated. Objective: To evaluate the accuracy of qPCR of rectal swab samples to differentiate foals with pneumonia from healthy foals of similar age from the same environment. Methods: One hundred privately owned foals born in 2021 from 2 farms in New York. Methods: An incident case-control study design was used. Rectal swabs were collected from all foals diagnosed with R. equi pneumonia at 2 horse-breeding farms (n = 47). Eligible pneu...
Suzuki Y, Takai S, Kubota H, Hasegawa N, Ito S, Yabuuchi Y, Sasaki Y, van Duijkeren E, Kakuda T.Rhodococcus equiis the causative agent of pyogenic pneumonia in foals, and a virulence-associated protein A (VapA) encoded on the pVAPA virulence plasmid is important for its pathogenicity. In this study, we analyzed the virulence of R. equi strain U19, originally isolated in the Netherlands in 1997 and the genetic characteristics of the pVAPA_U19 plasmid. U19 expressed VapA that was regulated by temperature and pH and underwent significant intracellular proliferation in macrophages. The restriction fragment length polymorphism of pVAPA_U19 digested with EcoRI was similar to that of pREAT701 (...
Malek G, Leclere M, Masseau I, Zur Linden A, Beauchamp G, Finck C.Published studies describing the effects of bilateral radiographic projections on the detection of equine pulmonary lesions are currently lacking. The objectives of this retrospective, single center, observational study were to compare unilateral and bilateral thoracic radiographic projections for the detection of pulmonary lesions in a group of horses. Based on their clinical diagnosis, 167 adults and foals with bilateral thoracic radiographs were classified as having pneumonia (n = 88), inflammatory or diffuse pulmonary disease (n = 72), and pulmonary masses (n = 7). After an initial i...
Arafa AA, Hedia RH, Dorgham SM, Ibrahim ES, Bakry MA, Abdalhamed AM, Abuelnaga ASM.The World Health Organization considers multidrug-resistant (MDR) a major global threat. Horses harbor commensal isolates of this bacterial species and potentially serve as reservoirs for human MDR bacteria. This study investigated antimicrobial resistance in horses caused by extended-spectrum β-lactamase (ESBL)-producing . Unassigned: One hundred fifty-nine nasal swab samples were collected from horses with respiratory distress not treated with cefotaxime and erythromycin. Biochemical and serological identification was performed on all samples. Polymerase chain reaction (PCR) was used to de...
Cohen ND, Kahn SK, Bordin AI, Gonzales GM, da Silveira BP, Bray JM, Legere RM, Ramirez-Cortez SC.Intragastric administration of virulent Rhodococcus equi protects foals against subsequent experimental intrabronchial (IB) infection, but it is unknown whether R. equi naturally ingested by foals contributes to their susceptibility to pneumonia. Objective: Fecal concentration of virulent R. equi before IB infection with R. equi is positively associated with protection from pneumonia in foals. Methods: Twenty-one university-owned foals. Methods: Samples were collected from experimental studies. Five foals were gavaged with live, virulent R. equi (LVRE) at age 2 and 4 days; the remaining 16 f...
Bordin AI, Huber L, Sanz MG, Cohen ND.Pneumonia in foals caused by the bacterium Rhodococcus equi has a worldwide distribution and is a common cause of disease and death for foals. The purpose of this narrative review was to summarise recent developments pertaining to the epidemiology, immune responses, treatment, and prevention of rhodococcal pneumonia of foals. Screening tests have been used to implement earlier detection and treatment of foals with presumed subclinical R. equi pneumonia to reduce mortality and severity of disease. Unfortunately, this practice has been linked to the emergence of antimicrobial-resistant R. equi i...
Mureşan A, Mureşan C, Siteavu M, Avram E, Bochynska D, Taulescu M.Equine herpesviruses are important pathogens causing significant economic loss in equine and asinine populations. EHV-1/4 strains are mainly associated with respiratory distress. The aim of this study is to report the first EHV 4-associated respiratory disease in donkeys in Romania. Thirty-seven of three hundred jennies in an ecological donkey farm in southwest Romania started initially showing signs of severe upper respiratory tract disease, with ten concomitant late abortions/neonatal deaths and three neurological cases. There were nine fatalities. Pathological examination was performed, and...
Mouncey R, Arango-Sabogal JC, de Mestre AM, Foote AK, Verheyen KL.Enhanced understanding of reasons for, and timings of, mortality in Thoroughbreds prior to entering race training is warranted to provide insight into this population's health status. The aims of this study were to describe pathologies diagnosed at post-mortem (PM) examination in Thoroughbreds aged from birth to 18 months and investigate associations between age and pathology. Reports from a pathology laboratory in Newmarket, UK, were used to identify eligible cases examined between January 2006 and December 2020. Reported pathologies were extracted and categorised where appropriate. Comorbidi...
Takai S, Yoda A, Sasaki Y, Kakuda T, Suzuki Y, Oikawa M.Tracheal washing fluid was collected from 170 foals at 28 and 35 d old from February to July in a foaling season on horse-breeding farms with sporadic rhodococcosis in Japan and was investigated by quantitative culture. The history of the 170 foals followed up for the next few months. The proportion of R. equi-positive foals at 28 and 35 d old was significantly increased according to the birth month. Furthermore, the mean number of R. equi in the tracheal washing fluid of each month group increased according to their birth month with the rise in outside temperature. During the follow-up observ...
Leise BS, Fugler LA.Sepsis or systemic inflammatory response syndrome (SIRS) -associated laminitis is a sequela to primary inflammatory conditions (eg, colitis, ischemic intestinal injury, pneumonia, metritis) and results from a dysregulated systemic inflammatory response that ultimately affects the digital lamellae. Local chemokine production, leukocyte migration, and proinflammatory mediator production occur within the lamellae that can lead to catastrophic lamellar failure. Controlling the primary disease, providing supportive care and anti-inflammatory therapy, applying digital cryotherapy, and providing mech...
Kahn SK, Cywes-Bentley C, Blodgett GP, Canaday NM, Turner-Garcia CE, Flores-Ahlschwede P, Metcalfe LL, Nevill M, Vinacur M, Sutter PJ, Meyer SC....Hyperimmune plasma raised against β-1→6-poly-N-acetyl glucosamine (PNAG HIP) mediates more opsonophagocytic killing of Rhodococcus equi (R equi) than does R equi hyperimmune plasma (RE HIP) in vitro. The relative efficacy of PNAG HIP and RE HIP to protect foals against R equi pneumonia, however, has not been evaluated. Objective: Transfusion with PNAG HIP will be superior to RE HIP in foals for protection against R equi pneumonia in a randomized, controlled, blinded clinical trial. Methods: Four hundred sixty Quarter Horse and Thoroughbred foals at 5 large breeding farms in the Un...
Akter R, El-Hage CM, Sansom FM, Carrick J, Devlin JM, Legione AR.Abortion in horses leads to economic and welfare losses to the equine industry. Most cases of equine abortions are sporadic, and the cause is often unknown. This study aimed to detect potential abortigenic pathogens in equine abortion cases in Australia using metagenomic deep sequencing methods. Results: After sequencing and analysis, a total of 68 and 86 phyla were detected in the material originating from 49 equine abortion samples and 8 samples from normal deliveries, respectively. Most phyla were present in both groups, with the exception of Chlamydiae that were only present in abortion sa...
Equine pulmonary aspergillosis is a rare deep mycosis often due to the hematogenous spread of hyphae after gastrointestinal tract disease. We describe herein the main clinic-pathological findings observed in a foal, which spontaneously died after showing diarrhea and respiratory distress. Necropsy and histopathological investigations allowed to diagnose pulmonary aspergillosis, which likely developed after necrotic typhlitis-colitis. Biomolecular studies identified section strain as the causative agent. Notably, severe oxalate nephrosis was concurrently observed. Occasionally, oxalate nephro...
Kahn SK, Cywes-Bentley C, Blodgett GP, Canaday NM, Turner-Garcia CE, Vinacur M, Cortez-Ramirez SC, Sutter PJ, Meyer SC, Bordin AI, Vlock DR, Pier GB....The efficacy of transfusion with hyperimmune plasma (HIP) for preventing pneumonia caused by Rhodococcus equi remains ill-defined. Quarter Horse foals at 2 large breeding farms were randomly assigned to be transfused with 2 L of HIP from adult donors hyperimmunized either with R. equi (RE HIP) or a conjugate vaccine eliciting antibody to the surface polysaccharide β-1→6-poly-N-acetyl glucosamine (PNAG HIP) within 24 hours of birth. Antibody activities against PNAG and the rhodococcal virulence-associated protein A (VapA), and to deposition of complement component 1q (C՛1q) onto PNAG were d...
Altan E, Hui A, Li Y, Pesavento P, Asín J, Crossley B, Deng X, Uzal FA, Delwart E.Six foals with interstitial pneumonia of undetermined etiology from Southern California were analyzed by viral metagenomics. Spleen, lung, and colon content samples obtained during necropsy from each animal were pooled, and nucleic acids from virus-like particles enriched for deep sequencing. The recently described equine copiparvovirus named eqcopivirus, as well as three previously uncharacterized viruses, were identified. The complete ORFs genomes of two closely related protoparvoviruses, and of a bocaparvovirus, plus the partial genome of a picornavirus were assembled. The parvoviruses were...
Cohen ND, Kahn SK, Cywes-Bentley C, Ramirez-Cortez S, Schuckert AE, Vinacur M, Bordin AI, Pier GB.Rhodococcus equi is a prevalent cause of pneumonia in foals worldwide. Our laboratory has demonstrated that vaccination against the surface polysaccharide β-1→6-poly-N-acetylglucosamine (PNAG) protects foals against intrabronchial infection with R. equi when challenged at age 28 days. However, it is important that the efficacy of this vaccine be evaluated in foals when they are infected at an earlier age, because foals are naturally exposed to virulent R. equi in their environment from birth and because susceptibility is inversely related to age in foals. Using a randomized, blind experim...
Kushugulova A, Löber U, Akpanova S, Rysbekov K, Kozhakhmetov S, Khassenbekova Z, Essex M, Nurgozhina A, Nurgaziyev M, Babenko D, Markó L....Probiotics and prebiotics are widely used for recovery of the human gut microbiome after antibiotic treatment. High antibiotic usage is especially common in children with developing microbiome. We hypothesized that dry Mare's milk, which is rich in biologically active substances without containing live bacteria, could be used as a prebiotic in promoting microbial diversity following antibiotic treatment in children. The present pilot study aims to determine the impacts of dry Mare's milk on the diversity of gut bacterial communities when administered during antibiotic treatment and throughout ...
Allegro AR, Barhoumi R, Bordin AI, Bray JM, Cohen ND.Rhodococcus equi is a soil saprophytic bacterium and intracellular pathogen that causes pneumonia in foals. Strains of R. equi that are virulent in foals contain a plasmid that encodes a virulence-associated protein A (VapA) necessary for replication in macrophages. Because other intracellular pathogens survive and replicate inside amoebae, we postulated that the VapA-bearing plasmid (pVAPA) confers a survival advantage for R. equi against environmental predators like amoebae. To test this hypothesis, we compared phagocytosis by and survival in Acanthamoeba castellanii of isogenic strains of p...
Punsmann S, Hellige M, Hoppe J, Freise F, Venner M.Acute interstitial pneumonia (AIP) in foals is a rare but challenging syndrome. Diagnostic imaging is crucial for its diagnosis. While there are some reports on radiographic findings, ultrasound is sparsely described. Variability in the evaluation of radiographs in AIP has been well described in human literature. Part one of this study is a prospective, observational, observer agreement study investigating inter- and intraobserver agreement in the assessment of thoracic radiographs. Part two is a prospective, controlled, descriptive study on thoracic ultrasonography in foals with AIP. Eighteen...
Huber L, Giguère S, Hart KA, Slovis NM, Greiter ME, Dailey CA, Cohen ND.To compare soil concentrations of macrolide- and rifampicin-resistant strains (MRRE) on horse-breeding farms that used thoracic ultrasonographic screening (TUS) to identify foals with subclinical pneumonia combined with subsequent administration of macrolides and rifampin to affected foals (TUS farms) versus soil concentrations on farms that did not (non-TUS farms), determine whether the combined use of TUS and antimicrobial treatment of subclinically affected foals was associated with soil concentration of MRRE, and assess whether there were temporal effects on soil concentrations of MRRE du...
Mondo E, Rinnovati R, Spadari A, Giacometti F, Serraino A, Savini F, Piva S.Respiratory diseases are the second most common cause of illnesses in horses, their etiology can be viral, bacterial, immune-mediated, or mechanical (Racklyeft and Love DN, Aust Vet J 78:549-59, 2000; Austin et al., J Am Vet Med Assoc 207:325-328, 1995; Arroyo et al., J Vet Intern Med 31:894-900, 2017). Klebsiella variicola is a Gram-negative bacterium that was initially identified as an endophyte in soil and plants such as bananas, rice, sugar cane and maize but recent studies have identified this microorganism as an emerging pathogen in humans (Rodríguez-Medina et al., Emerg Microbes Infec...
Sanclemente JL, Rivera-Velez SM, Dasgupta N, Horohov DW, Wood PL, Sanz MG.Many foals that develop thoracic ultrasonographic lesions as a result of Rhodococcus equi infection heal on their own. However, most of these foals receive antimicrobials because foals at risk of developing clinical pneumonia cannot be identified. Untargeted lipidomics is useful to identify candidate biomarkers. Objective: (a) To describe the changes that occur in foal lipidomics as a result of ageing (birth to 8 weeks) and (b) To compare these results with those observed in foals after experimental infection with R. equi. Methods: Experimental study. Methods: Healthy newborn foals (n = 9) ...
Bordin AI, Cohen ND, Giguère S, Bray JM, Berghaus LJ, Scott B, Johnson R, Hook M.Pneumonia caused by the intracellular bacterium Rhodococcus equi is an important cause of disease and death in immunocompromised hosts, especially foals. Antibiotics are the standard of care for treating R. equi pneumonia in foals, and adjunctive therapies are needed. We tested whether nebulization with TLR agonists (PUL-042) in foals would improve innate immunity and reduce the severity and duration of pneumonia following R. equi infection. Neonatal foals (n = 48) were nebulized with either PUL-042 or vehicle, and their lung cells infected ex vivo. PUL-042 increased inflammatory cytokines...
Harvey AB, Bordin AI, Rocha JN, Bray JM, Cohen ND.Evidence regarding the efficacy of equine hyperimmune plasma to prevent pneumonia in foals caused by Rhodococcus equi is limited and conflicting. Objective: Opsonization with R. equi-specific hyperimmune plasma (HIP) will significantly increase phagocytosis and decrease intracellular replication of R. equi by alveolar macrophages (AMs) compared to normal plasma (NP). Methods: Fifteen adult Quarter Horses were used to collect bronchoalveolar lavage cells. Methods: In the first experiment, AMs from 9 horses were pretreated (incubated) with either HIP, NP, or media only (control) and then infecte...
Adler DMT, Hopster K, Hopster-Iversen C, Fenner M, Buhl R, Jacobsen S.Thoracotomy is an uncommon procedure in horses but remains essential in a variety of cases of pleuropneumonia, pericarditis, thoracic trauma or diaphragmatic herniation, and for experimental thoracic and cardiac procedures. This study aimed at developing an experimental surgical procedure allowing access to the entire circumference of the heart and describing the effect of thoracotomy on pulmonary gas exchange in these horses. The study consisted of two arms, arm one (undergoing thoracotomy), was a terminal experimental study that included 11 Standardbred horses with experimentally induced (by...
Punsmann S, Hoppe J, Klopfleisch R, Venner M.Acute interstitial pneumonia in foals has been sparsely described in literature, and the individual authors disagree on the underlying aetiology. Histopathological follow-up from surviving foals is not available. Objective: Description of clinical and histopathological findings in the course of acute interstitial pneumonia and in recovery. Investigating the aetiology and possible triggering factors of acute interstitial pneumonia. Methods: Case series. Methods: Post-mortem examination of nine affected foals; seven died during the acute phase, and two had recovered from acute interstitial pneum...
Ferris RA, McCue PM, Borlee GI, Loncar KD, Hennet ML, Borlee BR.In this study, we evaluated the ability of the equine clinical treatments N-acetylcysteine, EDTA, and hydrogen peroxide to disrupt in vitro biofilms and kill equine reproductive pathogens (Escherichia coli, Pseudomonas aeruginosa, or Klebsiella pneumoniae) isolated from clinical cases. N-acetylcysteine (3.3%) decreased biofilm biomass and killed bacteria within the biofilms of E. coli isolates. The CFU of recoverable P. aeruginosa and K. pneumoniae isolates were decreased, but the biofilm biomass was unchanged. Exposure to hydrogen peroxide (1%) decreased the biofilm biomass and reduced the CF...
Cohen ND.Pneumonia caused by Rhodococcus equi is an important cause of disease and death in foals. This article reviews current knowledge of the epidemiology, clinical signs, diagnosis, treatment, prevention, and control of R equi pneumonia in foals.
Hooper PT, Ketterer PJ, Hyatt AD, Russell GM.Laboratory examinations of equine morbillivirus included experimental reproductions of the disease caused by the virus by transmission of mixed lung and spleen taken from two field equine cases into two horses and by inoculating tissue culture virus into a further two horses. The most distinctive gross lesions of the diseases that developed in three of the horses was that of pulmonary edema characterized by gelatinous distension of subpleural lymphatics. Histologically, the lesions in the lungs were those of serofibrinous alveolar edema, alveolar macrophages, hemorrhage, thrombosis of capillar...
Giguère S, Berghaus LJ, Willingham-Lane JM.Pneumonia caused by remains an important cause of disease and death in foals. The combination of a macrolide (erythromycin, azithromycin, or clarithromycin) with rifampin has been the recommended treatment for foals with clinical signs of infection caused by since the early 1980s with, until recently, only rare reports of resistance. Resistance to macrolides and rifampin in isolates of cultured from horses is increasing, with isolates resistant to all macrolides and rifampin now being cultured from up to 40% of infected foals at some farms. This text reviews the available data regarding ant...
Giguère S.Pneumonia caused by Rhodococcus equi remains an important cause of disease and death in foals. The combination of a macrolide (erythromycin, azithromycin, or clarithromycin) with rifampin remains the recommended therapy for foals with clinical signs of infection caused by R equi. Most foals with small, subclinical ultrasonographic pulmonary lesions associated with R equi recover without therapy, and administration of antimicrobial agents to these subclinically affected foals does not hasten lesion resolution relative to administration of a placebo. Resistance to macrolides and rifampin in isol...
Muscatello G, Anderson GA, Gilkerson JR, Browning GF.The ecology of virulent strains of Rhodococcus equi on horse farms is likely to influence the prevalence and severity of R. equi pneumonia in foals. This study examined the association between the ecology of virulent R. equi and the epidemiology of R. equi pneumonia by collecting air and soil samples over two breeding seasons (28 farm-year combinations) on Thoroughbred breeding farms with different reported prevalences of R. equi pneumonia. Colony blotting and DNA hybridization were used to detect and measure concentrations of virulent R. equi. The prevalence of R. equi pneumonia was associate...
Hobo S, Niwa H, Anzai T.In the present study, the concentrations of serum amyloid A and surfactant protein D in sera were measured to evaluate them for identification of the clinical condition of horses with bacterial pneumonia. The study utilized 185 clinically healthy control thoroughbreds and 9 thoroughbreds for experimental infectious study with S. zooepidemicus. Blood samples were collected from the 185 healthy control thoroughbreds. The 9 thoroughbreds were experimentally infected S. zooepidemicus using an endoscopic injection to a lung lobe and were then observed of clinical conditions. Blood samples were coll...
Dei-Cas E, Brun-Pascaud M, Bille-Hansen V, Allaert A, Aliouat EM.As in vitro culture systems allowing to isolate Pneumocystis samples from patients or other mammal hosts are still not available, animal models have critical importance in Pneumocystis research. The parasite was reported in numerous mammals but P. carinii pneumonia (PCP) experimental models were essentially developed by using rats, mice, rabbits and ferrets. The rat treated with corticosteroids for 9-12 weeks is a useful PCP model. Like laboratory rats, conventional mice develop PCP after prolonged corticosteroid administration. The ferret (Mustela putorius furo) also develop PCP under cortico...
Halbert ND, Reitzel RA, Martens RJ, Cohen ND.To evaluate sensitivity and specificity of a multiplex polymerase chain reaction (PCR) assay for simultaneous detection of Rhodococcus equi and differentiation of strains that contain the virulence-associated gene (vapA) from strains that do not. Methods: 187 isolates of R equi from equine and nonequine tissue and environmental specimens and 27 isolates of bacterial species genetically or morphologically similar to R equi. Methods: The multiplex PCR assay included 3 gene targets: a universal 311-bp bacterial 16S ribosomal RNA amplicon (positive internal control), a 959-bp R equi-specific targe...
Arroyo MG, Slovis NM, Moore GE, Taylor SD.Septic pleuropneumonia is a common cause of morbidity and mortality in horses, but there is limited data available regarding factors associated with survival. Objective: To identify factors predictive of survival in horses with septic pleuropneumonia. Methods: A total of 97 horses with septic pleuropneumonia at 2 referral institutions. Methods: A retrospective study was performed. A diagnosis of septic pleuropneumonia was based on the presence of sepsis, pleural effusion, and positive bacterial culture from tracheal aspiration (TA) or pleural fluid (PF). Results: Thirty-one percent of horses h...
Gustafsson A, Båverud V, Gunnarsson A, Rantzien MH, Lindholm A, Franklin A.In Sweden there are several reports of mares developing acute colitis while their foals were being treated orally for Rhodococcus equi pneumonia with the combination of erythromycin and rifampicin. In this study 6 adult horses were given low oral dosages of these antibiotics, singly or in combination. Within 3 days post administration of erythromycin, in one case in combination with rifampicin, 2 horses developed severe colitis (one fatal). Clostridium difficile was isolated from one of the horses, whereas no specific pathogens were isolated from the other. Both horses had typical changes in b...
Giguère S, Gaskin JM, Miller C, Bowman JL.To determine efficacy of a commercially available hyperimmune plasma product for prevention of naturally acquired pneumonia caused by Rhodococcus equi in foals. Methods: Randomized clinical trial. Methods: 165 foals. Methods: Foals were randomly assigned to 1 of 2 groups (hyperimmune plasma or nontreated controls). Foals with failure of passive transfer (FPT) of immunity were treated with hyperimmune plasma and evaluated as a third group. Foals that received plasma were given 950 ml between 1 and 10 days of age and between 30 and 50 days of age. A tracheobronchial aspirate was obtained from fo...
Whatmore AM, King SJ, Doherty NC, Sturgeon D, Chanter N, Dowson CG.Although often considered a strict human pathogen, Streptococcus pneumoniae has been reported to infect and cause pneumonia in horses, although the pathology appears restricted compared to that of human infections. Here we report on the molecular characterization of a group of S. pneumoniae isolates obtained from horses in England and Ireland. Despite being obtained from geographically distinct locations, the isolates were found to represent a tight clonal group, virtually identical to each other but genetically distinguishable from more than 120 divergent isolates of human S. pneumoniae. A co...
Cauchard S, Bermúdez-Humarán LG, Blugeon S, Laugier C, Langella P, Cauchard J.Rhodococcus equi causes severe pneumonia in foals and has recently gained attention as a significant opportunistic pathogen in immunocompromised humans. However, no effective vaccine to prevent rhodococcosis is currently available. In this study, we have engineered the food-grade bacterium Lactococcus lactis to secrete the virulence-associated protein A from R. equi (LL-VapA). The immunogenic potential of LL-VapA strain was then evaluated after either intragastric or intranasal immunization in mice either alone or in combination with LL-Lep, a recombinant strain of L. lactis secreting biologic...
Hooper-McGrevy KE, Wilkie BN, Prescott JF.The purpose of this study was to determine whether foals immunized orally from 2 days of age with virulent Rhodococcus equi developed a protective pulmonary immune response and to characterise the antibody response of the immunized foals to the virulence-associated proteins (Vaps) of the bacterium. Two groups of foals were used. One (n=4) was given live R. equi ATCC 33701 orally at 2, 7, and 14 days of age. The second group comprised three non-immunized foals age-matched to the vaccinates. At 3 weeks of age, 1 week after the final immunization, both groups were challenged intrabronchially with...
Madigan JE, Hietala S, Muller N.A 2-year field study was performed to determine the capability of increasing Rhodococcus equi specific antibody in foals via plasma transfusion or mare vaccination, to determine the kinetics of R. equi (ELISA) antibody decay and to assess the protective effects of these procedures in foals on a farm endemic for R. equi. Plasma donors were vaccinated with a killed R. equi bacterin and produced high levels of anti-R. equi antibodies, which were harvested by plasmapheresis. In Experiment 1, 68 foals were given 1 litre of hyperimmune plasma intravenously (i.v.) between 1-60 days of age. Foal plasm...
Sweeney CR, Holcombe SJ, Barningham SC, Beech J.Frequency of aerobic and anaerobic isolates in 327 aspirates and in 123 pleural fluid samples from 327 horses with pneumonia or pleuropneumonia and antimicrobial susceptibility patterns of the aerobes were reported. Of the 327 horses, 75% survived, 20% were euthanatized, and 5% died. Tracheobronchial aspirates or pleural fluid specimens from 25 of the horses did not yield growth. Of the remaining 302 horses, 221 had only aerobic organisms isolated, whereas only anaerobes were isolated from 6 of the 302 horses. The remaining 75 horses had mixed aerobic and anaerobic bacterial infections. The su...
Huber L, Giguère S, Cohen ND, Slovis NM, Hanafi A, Schuckert A, Berghaus L, Greiter M, Hart KA.The combination of a macrolide and rifampicin has been the mainstay of therapy in foals with Rhodococcus equi pneumonia for decades. Recent studies suggest that mass antimicrobial treatment of subclinically affected foals over time has selected for antimicrobial resistance. Our objective was to estimate the prevalence of R. equi strains resistant to macrolides and rifampicin at horse breeding farms in Kentucky. A hundred breeding farms in Kentucky were surveyed and R. equi were cultured from soil samples. Data were analyzed with logistic regression and generalized linear modeling (P < 0...
Hines MT, Paasch KM, Alperin DC, Palmer GH, Westhoff NC, Hines SA.Rhodococcal pneumonia is an important disease of young horses that is not seen in immunocompetent adults. Since all foals are normally exposed to Rhodococcus equi in their environment, we hypothesized that most develop protective immune responses. Furthermore, these antigen-specific responses were hypothesized to operate throughout adult life to prevent rhodococcal pneumonia. A better understanding of the mechanisms of immune clearance in adult horses would help define the requirements for an effective vaccine in foals. Adult horses were challenged with virulent R. equi by intrabronchial inocu...
Giguère S, Jacks S, Roberts GD, Hernandez J, Long MT, Ellis C.The objective of this retrospective study was to compare the efficacy of azithromycin-rifampin, clarithromycin-rifampin, and erythromycin-rifampin for the treatment of pneumonia caused by Rhodococcus equi in foals. Eighty-one foals with naturally acquired pneumonia caused by R. equi were included in the study. Information on age, sex, breed, physical examination findings, laboratory testing, and thoracic radiography was abstracted from each medical record. Foals were divided in 3 groups based on the antimicrobial agent selected for therapy. Short-term (discharge from the hospital) and long-ter...
Austin SM, Foreman JH, Hungerford LL.Risk factors for development of pleuropneumonia were determined by reviewing medical records of 45 horses with pleuropneumonia and 180 control horses examined between Jan 1, 1980 and Jan 1, 1990. Factors considered included age, breed, sex, occupation, transport farther than 500 miles within the previous week, racing within the previous 48 hours, viral respiratory tract infection or exposure to horses with viral respiratory tract disease within the previous 2 weeks, and vaccination against influenza or rhinopneumonitis within the previous 6 months. Results indicated that Thoroughbreds were at ...
Wood JL, Burrell MH, Roberts CA, Chanter N, Shaw Y.The likelihood of finding evidence of inflammation in 551 tracheal washes collected endoscopically from 278 Thoroughbred racehorses increased with the number of bacterial colony forming units (cfu) per ml of wash (P < 0.001). The aerobic bacteria Streptococcus zooepidemicus, Pasteurella/Actinobacillus-like species and Streptococcus pneumoniae were significantly associated with lower airway inflammation whereas coagulase-negative Staphylococcus spp., alpha-haemolytic Streptococcus spp., Acinetobacter spp., Bacillus spp., Escherichia coli, Pseudomonas aeruginosa, non-haemolytic Streptococcus spp...
Kleiboeker SB, Schommer SK, Johnson PJ, Ehlers B, Turnquist SE, Boucher M, Kreeger JM.Over a period of 6 years, antemortem and postmortem examinations were performed on a number of donkeys suffering from respiratory disease. For many cases, initial diagnostic efforts failed to identify an etiology consistent with the pathologic findings. However, retrospective examination of these cases using consensus primer polymerase chain reaction, designed to recognize herpesviruses from all 3 subfamilies of the Herpesviridae, amplified a fragment of the highly conserved herpesvirus DNA polymerase gene from a number of these animals. Two novel herpesviruses, herein designated asinine herpe...
Johnson JA, Prescott JF, Markham RJ.Six foals were inoculated intrabronchially with a suspension of Corynebacterium equi. Six weeks before this challenge, three foals were vaccinated with a C. equi bacterin. Three foals were unvaccinated controls. All foals developed a severe bronchopneumonia in the inoculated lung, indicating that vaccination was not protective. Three foals (two vaccinated, one control) were killed eight to nine days after infection. One control died on day 9 with lesions of disseminated intravascular coagulation. The remaining two foals (one vaccinated, one control) were killed on day 17. C. equi was cultured ...
Båverud V.In human medicine, Clostridium (C.) difficile is since many years a well-known cause of nosocomial diarrhea induced by antibiotic treatment. In horses, C. difficile was recently suggested as a possible enteric pathogen. The bacterium is associated with acute colitis in mature horses following treatment with antibiotics. C. difficile, and/or its cytotoxin, is also associated with acute colitis in mares when their foals are being treated with erythromycin and rifampicin for Rhodococcus equi pneumonia. The colitis can have resulted from an accidental ingestion of erythromycin by the mares. In an ...
Zink MC, Yager JA, Smart NL.Of 131 cases of Corynebacterium equi infection in horses submitted for necropsy to the Ontario Veterinary College or Veterinary Laboratory Services, OMAF, Guelph, Ontario from 1958 to 1984, 115 were diagnosed as suppurative pneumonia, and of these 55 had associated ulcerative enterocolitis. Only five animals had intestinal involvement without pulmonary lesions. The remaining 11 cases included arthritis/cellulitis, skin abscesses and submandibular lymphadenitis. While the lung, intestine and associated lymph nodes yielded C. equi most frequently, in 21% of cases C. equi was also cultured from p...
Chirino-Trejo JM, Prescott JF, Yager JA.Two groups of three one to three week old foals were immunized orally on four occasions over five weeks with two strains of Rhodococcus equi, a clinical isolate from a pneumonic foal and a laboratory passaged Congo red negative variant of this strain. Three nonimmunized foals of similar age acted as controls. Three weeks after the last immunization, all foals were challenged on five occasions over seven days by aerosol infection with about 10(10) of the pneumonic foal isolate on each occasion. Control foals became seriously ill and were euthanized. Immunization with either strain protected foa...
Huber L, Giguère S, Slovis NM, Carter CN, Barr BS, Cohen ND, Elam J, Erol E, Locke SJ, Phillips ED, Smith JL.The objective of this study was to determine the prevalence of strains resistant to macrolides and rifampin over time in clinical samples from foals submitted to diagnostic laboratories in central Kentucky. We performed a retrospective observational study of all clinical samples from foals that were submitted to veterinary diagnostic laboratories in Kentucky between January 1995 and December 2017. Samples were included if the bacterium was cultured and tested for susceptibility to erythromycin or rifampin. susceptibility testing to erythromycin was available for 2,169 isolates of , while s...
Martens RJ, Fiske RA, Renshaw HW.Subacute pyogranulomatous pneumonia was experimentally induced in 3 neonatal foals following multiple challenge with aerosols containing Corynebacterium equi. On each of 7 consecutive days the foals were exposed to approximately 3.5 X 10(7) viable C equi in droplets small enough to reach the terminal airways. Clinical, pathological and bacteriological features of the induced syndrome were indistinguishable from those exhibited by cases with spontaneous subacute C equi foal pneumonia. Radiographic evidence of advanced pulmonary damage preceded the appearance of clinical signs and ante mortem cu...
Barton AK, Shety T, Bondzio A, Einspanier R, Gehlen H.In chronic respiratory disease, matrix metalloproteinases (MMPs) contribute to pathological tissue destruction when expressed in excess, while tissue inhibitors of metalloproteinases (TIMPs) counteract MMPs with overexpression leading to fibrosis formation. They may be out of balance in equine pneumopathies and serve as biomarkers of pulmonary inflammation. We hypothesized that MMPs and TIMPs correlate to clinical findings and bronchoalveolar lavage fluid cytology in different equine chronic pneumopathies. Using a scoring system, 61 horses were classified controls as free of respiratory diseas...
