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.
Sanz MG, Villarino N, Ferreira-Oliveira A, Horohov DW.Rhodococcus equi is a common cause of pneumonia in young foals worldwide and has considerable economic effects on the global equine industry. Despite ongoing efforts, no vaccine is currently available to prevent rhodococaal pneumonia. This is due, in part, to an incomplete understanding of the protective immune response to this bacterium. While antibodies to VapA, a lipoprotein produced by virulent R. equi, are useful in differentiating antibody production in response to pathogenic versus non-pathogenic strains, the significance of the humoral response of foals to this lipoprotein remains poor...
Reuss SM, Giguère S.Bacterial infections of the lower respiratory tract in adult horses occur when bacteria from the nasopharynx reach the lower airways and overwhelm normal defense mechanisms. Although Streptococcus equi subsp zooepidemicus is the most commonly isolated bacterial species, mixed infections are possible. Tracheobronchial aspiration for microbiologic culture and sensitivity is suggested in cases presenting with severe clinical signs or not responding to treatment. Early intervention and appropriate antimicrobial selection results in a good prognosis for both survival and return to athletic function...
Reuss SM, Cohen ND.Bacterial pneumonia is a common cause of disease in both neonatal and weanling foals. The causal organism or organisms differ with the age of the foal, should be identified via microbiologic culture, and will ultimately dictate appropriate treatment. Initial treatment in neonates should be broad spectrum and bactericidal, whereas weanling age foals may receive more targeted treatment. The combination of a macrolide antibiotic and rifampin remains the gold standard for treatment of Rhodococcus equi pneumonia; however, resistance to these antimicrobials is a concern.
Passamonti F, Vardi DM, Stefanetti V, Marenzoni ML, Prato S, Cévese P, Coletti M, Pepe M, Casagrande Proietti P, Olea-Popelka F.Early diagnosis and prevention of Rhodococcus equi pneumonia in foals represent important goals for equine clinicians. Recent protocols for diagnosis and treatment of Rhodococcosis in foals typically rely on a multimodal approach based on sonographic evidence suggestive of pyogranulomas, sonographic abscess scores and laboratory findings including plasma fibrinogen concentrations, blood biochemistry testing and platelet and leukocyte counts. The aim of this study was to assess the utility of weekly testing of serum amyloid A (SAA) and plasma fibrinogen concentrations in foals to achieve early ...
Passamonti F, Vardi DM, Stefanetti V, Marenzoni ML, Prato S, Cévese P, Coletti M, Pepe M, Casagrande Proietti P, Olea-Popelka F.Early diagnosis and prevention of Rhodococcus equi pneumonia in foals represent important goals for equine clinicians. Recent protocols for diagnosis and treatment of Rhodococcosis in foals typically rely on a multimodal approach based on sonographic evidence suggestive of pyogranulomas, sonographic abscess scores and laboratory findings including plasma fibrinogen concentrations, blood biochemistry testing and platelet and leukocyte counts. The aim of this study was to assess the utility of weekly testing of serum amyloid A (SAA) and plasma fibrinogen concentrations in foals to achieve early ...
Gazzerro DM, Southwood LL, Lindborg S.To compare in geriatric and mature horses the occurrence of short-term complications and short-term outcome associated with complications after colic surgery. Methods: Retrospective case-control study. Methods: Horses aged ≥20 years (geriatric, n = 78) and 4-15 years (mature non-geriatric, n = 156) that had exploratory celiotomy for colic and survived recovery from general anesthesia. Methods: Medical records (2000-2010) of horses that recovered from general anesthesia after colic surgery were reviewed. Postoperative complications evaluated included postoperative reflux (POR), diarrh...
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.
Fultz L, Giguère S, Berghaus LJ, Grover GS, Merritt DA.Administration of ceftiofur sodium via nebulisation has been recommended for the treatment of bronchopneumonia in horses, despite the lack of pharmacokinetic and safety data. Objective: To compare concentrations of desfuroylceftiofur acetamide (DCA) in plasma and pulmonary epithelial lining fluid (PELF) of foals after nebulisation or i.m. administration of ceftiofur sodium and to determine if nebulisation of ceftiofur sodium induces airway inflammation. Methods: Randomised experimental study. Methods: Six weanling foals received ceftiofur sodium (2.2 mg/kg bwt daily for 5 doses) by the i.m. ...
Bordin AI, Pillai SD, Brake C, Bagley KB, Bourquin JR, Coleman M, Oliveira FN, Mwangi W, McMurray DN, Love CC, Felippe MJ, Cohen ND.Rhodococcus equi is an important pathogen of foals that causes severe pneumonia. To date, there is no licensed vaccine effective against R. equi pneumonia of foals. The objectives of our study were to develop an electron beam (eBeam) inactivated vaccine against R. equi and evaluate its immunogenicity. A dose of eBeam irradiation that inactivated replication of R. equi while maintaining outer cell wall integrity was identified. Enteral administration of eBeam inactivated R. equi increased interferon-γ production by peripheral blood mononuclear cells in response to stimulation with virulent R. ...
Sanz MG, Oliveira AF, Page A, Horohov DW.Rhodococcus equi is the most common cause of pneumonia in young foals. A vaccine is not available and the use of R equi-specific hyperimmune plasma (HIP) is common. Despite its widespread use, the efficacy of HIP in preventing disease remains controversial. The objectives of this study were (1) to evaluate the virulence associate protein A (VapA)-specific IgG and IgG subclasses in commercially available R equi HIP and (2) to evaluate serum VapA-specific IgG and IgG subclasses in foals following administration of commercial R equi HIP. Three different lots from four commercial R equi HIP were s...
Johnson L, Montgomery JB, Schneider JP, Townsend HG, Ochs M, Singh B.To understand the mechanisms of airway inflammation associated with equine diseases such as Rhodococcus equi infection, we must identify baseline "normal" structural characteristics of the horse lung. To develop a detailed understanding of the morphology of the horse lung, we adapted and applied stereological methods to the lungs from healthy adult horses (N = 4) and 1-day (N = 5) and 30-day (N = 5) old foals. The left lung was fixed in situ by intrabronchial instillation of glutaraldehyde/paraformaldehyde fixative at 25 cm H2 O column and sampled using a fractionator design follow...
Chambers TM.Equine influenza virus (EIV) is a common respiratory pathogen of horses and other equids in most parts of the world. EIV are Type A influenza viruses and two subtypes are known: H3N8 and H7N7. Both are believed to have evolved from avian influenza virus ancestors. The H3N8 subtype circulates widely, but the H7N7 subtype is thought to be extinct. The clinical disease in horses, caused by either subtype, is an upper respiratory infection of varying severity depending upon the immune status of the individual animal. It is not normally life-threatening in itself except in very young foals; however...
Miele A, Dhaliwal K, Du Toit N, Murchison JT, Dhaliwal C, Brooks H, Smith SH, Hirani N, Schwarz T, Haslett C, Wallace WA, McGorum BC.Donkey pulmonary fibrosis (DPF) is a spontaneous syndrome of aged donkeys with a high prevalence (35%). No previous detailed characterization of DPF has been performed. We sought to determine the similarities between DPF and recognized patterns of human pulmonary fibrosis. Methods: Whole lungs were collected from 32 aged donkeys at routine necropsy. Gross examination revealed pulmonary fibrosis in 19 donkeys (DPF cases), whereas 13 (control cases) had grossly normal lungs. Eighteen whole inflated ex vivo lungs (11 DPF cases, seven control cases) were imaged with high-resolution CT (HRCT) scan,...
McQueen CM, Doan R, Dindot SV, Bourquin JR, Zlatev ZZ, Chaffin MK, Blodgett GP, Ivanov I, Cohen ND.Pneumonia caused by Rhodococcus equi is a common cause of disease and death in foals. Although agent and environmental factors contribute to the incidence of this disease, the genetic factors influencing the clinical outcomes of R. equi pneumonia are ill-defined. Here, we performed independent single nucleotide polymorphism (SNP)- and copy number variant (CNV)-based genome-wide association studies to identify genomic loci associated with R. equi pneumonia in foals. Foals at a large Quarter Horse breeding farm were categorized into 3 groups: 1) foals with R. equi pneumonia (clinical group [N = ...
Kinoshita Y, Niwa H, Katayama Y.Streptococcus equi subsp. zooepidemicus (S. zooepidemicus) is a dominant pathogenic bacterium in equine pneumonia. We developed a specific loop-mediated isothermal amplification (LAMP) method, which targets the gene encoding sorbitol-6-phosphate 2-dehydrogenase (sorD), for detecting S. zooepidemicus and examined the clinical efficacies of its use in combination with each of 3 DNA extraction methods easily used by veterinary practitioners, namely the Loopamp PURE DNA Extraction Kit, InstaGene Matrix and a conventional boiling method. The LAMP method plus the Loopamp PURE DNA Extraction Kit gave...
Preziuso S, Pinho MD, Attili AR, Melo-Cristino J, Acke E, Midwinter AC, Cuteri V, Ramirez M.Streptococcus dysgalactiae subsp. equisimilis (SDSE) can be severely pathogenic in humans and is increasingly isolated from horses with respiratory, reproductive or other diseases, although it is often considered a commensal bacterium. Here a PCR protocol is described for identifying SDSE recovered from humans. A multiplex PCR targeting the 16S rRNA and the streptokinase precursor gene has been optimized for differentiating between SDSE strains isolated from humans and those isolated from horses. Previously, the sequence of the streptokinase precursor gene of SDSE recovered from horses has bee...
Erganis O, Sayin Z, Hadimli HH, Sakmanoglu A, Pinarkara Y, Ozdemir O, Maden M.This study aimed to determine the effectiveness of a pregnant mare immunization of a Rhodococcus equi (R. equi) vaccine candidate containing a water-based nanoparticle mineral oil adjuvanted (Montanide IMS 3012) inactive bacterin and virulence-associated protein A (VapA), as well as the administration of anti-R. equi hyperimmune (HI) plasma against R. equi challenge in the mares' foals. The efficacy of passive immunizations (colostral passive immunity by mare vaccination and artificial passive immunity by HI plasma administration) was evaluated based on clinical signs, complete blood count, bl...
Berghaus LJ, Giguère S, Sturgill TL.Rhodococcus equi, a facultative intracellular pathogen of macrophages, causes life-threatening pneumonia in foals and in people with underlying immune deficiencies. As a basis for this study, we hypothesized that macrophage lineage and age would affect intracellular survival of R. equi and cytokine induction after infection. Monocyte-derived and bronchoalveolar macrophages from 10 adult horses and from 10 foals (sampled at 1-3 days, 2 weeks, 1 month, 3 months, and 5 months of age) were infected ex vivo with virulent R. equi. Intracellular R. equi were quantified and mRNA expression of IL-1β, ...
Dunowska M, Hardcastle MR, Tonkin FB.A 10-year-old polo mare presented with a history of weight loss, poor condition and inappetance. Results: The mare was tachycardic, tachypnoeic and febrile. Harsh lung sounds were auscultated over all lung fields. The mare initially responded to treatment with antibiotics, anti-inflammatory drugs and bronchodilators. Throughout the course of treatment, there was a variable lymphocytosis, monocytosis and fluctuation in concentrations of fibrinogen. The mare also developed a mild anaemia, most likely due to chronic disease. Despite treatment, the mare's condition deteriorated over the following ...
Zantingh AJ, Schwark WS, Fubini SL, Watts AE.To determine the effect of regional limb perfusion (RLP) with amikacin sulfate alone and in combination with ticarcillin/clavulanate on synovial fluid concentration and antimicrobial activity of amikacin. Methods: Experimental study. Methods: RLP with amikacin alone (A; 2.5 g) or amikacin and ticarcillin/clavulanate (AT; 2.5 g amikacin, 7 g ticarcillin/clavulanate) was performed with a tourniquet placed at mid-antebrachium in standing, sedated horses. Perfusate blood was collected immediately after injection and again before tourniquet release. Blood from the jugular vein was collected before ...
Headley SA, de Carvalho PH, Cunha Filho LF, Yamamura AA, Okano W.The cause of the death of a 16-month-old Brasileiro-de-Hipismo filly and a 3-year-old male Paint Horse with clinical manifestations of anemia and apathy from southern Brazil was investigated. These horses were maintained at the same stable; received hay as part of their diet and were submitted for routine necropsy evaluations. Significant gross findings included several nodules randomly distributed throughout the pulmonary lobes of both horses, and the kidneys, myocardium, and the frontal lobes of the cerebrum of the filly. Histopathological evaluation revealed pyogranulomatous bronchopneumoni...
Morrell JM, Klein C, Lundeheim N, Erol E, Troedsson MH.Bacteria (environmental contaminants and occasionally potential pathogens) are found in most stallion ejaculates and may negatively affect sperm quality during storage. Since the use of antibiotics can lead to the development of resistance, an alternative means of microbial control is desirable. The removal of bacteria from stallion semen using Single Layer Centrifugation through Androcoll-E was investigated. Known doses of cultured bacteria were added to freshly collected ejaculates (15mL aliquots) before processing by Single Layer Centrifugation. The resulting sperm pellets and controls (not...
Kaur N, Townsend H, Lohmann K, Marques F, Singh B.Rhodococcus equi establishes long-term pulmonary infection, survives in phagolysosomes of alveolar macrophages and causes pneumonia in foals. The failure of the foal to clear R. equi bacteria is believed to be due to its inability to produce IFN-γ and defects in Toll-like receptor(TLR) signaling. Lipid rafts sequester immune receptors such as TLRs and facilitate efficient cell signaling and therefore, a deficiency in accumulation of receptors in lipid rafts may result in failure to activate. We tested whether a Virulence Associated Protein A (VapA)/CpG vaccine against R. equi would impact the...
Kinoshita Y, Niwa H, Katayama Y, Hariu K.Obligate anaerobes are important etiological agents in pneumonia or pleuropneumonia in horses, because they are isolated more commonly from ill horses that have died or been euthanized than from those that survive. We performed bacterial identification and antimicrobial susceptibility testing for obligate anaerobes to establish effective antimicrobial therapy. We used 16S rRNA gene sequencing to identify 58 obligate anaerobes and compared the results with those from a phenotypic identification kit. The identification results of 16S rRNA gene sequencing were more reliable than those of the comm...
Schlusselhuber M, Guldbech K, Sevin C, Leippe M, Petry S, Grötzinger J, Giguère S, Cauchard J.The equine antimicrobial peptide eCATH1 previously has been shown to have in vitro activity against antibiotic-susceptible reference strains of Rhodococcus equi and common respiratory bacterial pathogens of foals. Interestingly, eCATH1 was also found to be effective in the treatment of R. equi infection induced in mice. The aim of this study was to assess the in vitro activity of eCATH1 against equine isolates of Gram-negative (Escherichia coli, Salmonella enterica, Klebsiella pneumoniae and Pseudomonas spp.) and Gram-positive (R. equi, Staphylococcus aureus) bacteria resistant to multiple cla...
Cauchard S, Bertrand F, Barrier-Battut I, Jacquet S, Laurentie M, Barbey C, Laugier C, Deville S, Cauchard J.Rhodococcus equi is the most common infectious cause of mortality in foals between 1 and 6 months of age. Because of an increase in the number of antibiotic-resistant strains, the optimization of a prophylactic strategy is a key factor in the comprehensive management of R. equi pneumonia. The objectives of this study were to assess the safety and immunogenicity of R. equi-secreted proteins (ReSP) co-administered with either the nanoparticular adjuvant Montanide™ IMS 3012 VG, or a new polymeric adjuvant Montanide™ PET GEL A, and to further investigate the most immunogenic proteins for subse...
Lawhon SD, Lopez FR, Joswig A, Black HC, Watts AE, Norman TE, Porter BF.Weissella confusa is a Gram-positive bacterium that has been identified in environmental and food samples from around the world. Rare cases of bacteremia in immunocompromised people have been reported. A 2-day-old foal was presented for weakness and suspected sepsis. Blood culture yielded pure growth of a Gram-positive coccobacillus, which was identified as W. confusa through sequencing of the 16S ribosomal DNA. Although the foal initially responded to antimicrobial therapy with ceftiofur and metronidazole, it later developed septic complications of the right tarsocrural joint and right digita...
Crowley J, Po E, Celi P, Muscatello G.Oxidative stress (OS) is most simply defined as an imbalance between oxidants and antioxidants. Oxidative stress has been suggested to play roles in various equine respiratory diseases and the significance of OS in the pathogenesis of Rhodococcus equi pneumonia is unknown. Objective: To measure and relate biomarkers of OS to lesions consistent with R. equi pneumonia. Methods: Case-control study. Methods: Various OS biomarkers were measured from blood and exhaled breath condensate (EBC) samples collected from 26 foals between 1 and 2 months of age (n = 12 cases and n = 14 controls) on 2 Thoro...
Stratton-Phelps M, Wilson WD, Gardner IA.To determine whether foals with pneumonia that were treated with erythromycin, alone or in combination with rifampin or gentamicin, had a higher risk of developing adverse effects, compared with foals treated with trimethoprim-sulfamethoxazole (TMS), penicillin G procaine (PGP), or a combination of TMS and PGP (control foals). Methods: Retrospective study. Methods: 143 foals < 240 days old. Methods: Information on age, sex, breed, primary drug treatment, total days of treatment with the primary drug, and whether the foal developed diarrhea, hyperthermia, or respiratory distress was obtained...
Okoko T, Blagova EV, Whittingham JL, Dover LG, Wilkinson AJ.Virulence and host range in Rhodococcus equi depends on the variable pathogenicity island of their virulence plasmids. Notable gene products are a family of small secreted virulence-associated proteins (Vaps) that are critical to intramacrophagic proliferation. Equine-adapted strains, which cause severe pyogranulomatous pneumonia in foals, produce a cell-associated VapA that is necessary for virulence, alongside five other secreted homologues. In the absence of biochemical insight, attention has turned to the structures of these proteins to develop a functional hypothesis. Recent studies have ...
Rocha JN, Dangott LJ, Mwangi W, Alaniz RC, Bordin AI, Cywes-Bentley C, Lawhon SD, Pillai SD, Bray JM, Pier GB, Cohen ND.Prescottella equi (formerly Rhodococcus equi) is a facultative intracellular bacterial pathogen that causes severe pneumonia in foals 1-6 months of age, whereas adult horses are highly resistant to infection. We have shown that vaccinating pregnant mares against the conserved surface polysaccharide capsule, β-1 → 6-linked poly-N-acetyl glucosamine (PNAG), elicits opsonic killing antibody that transfers via colostrum to foals and protects them against experimental infection with virulent. R. equi. We hypothesized that equine IgG might be more important than IgG for mediating protection...
Raidal SL.Pleuropneumonia is a clinically important equine disease, predisposed by a number of identifiable factors. Successful management is largely dependent on early identification and prompt initiation of appropriate treatment strategies. Rapid resolution of the disease process is associated with appropriate treatment commenced within 48 h of the causative insult. Lower airway contamination by oropharyngeal organisms and subsequent extension into the pulmonary parenchyma results in respiratory dysfunction and systemic toxaemia. Acute disease is associated with the isolation of facultatively anaerobi...
Barr BS.Lower respiratory tract infection is common in weanling- and suckling-aged animals. Increased susceptibility to disease in this age group can result from a delay in the establishment of a competent immune system and environmental factors, such as overcrowding, shipping, and sales. S zooepidemicus and R equi are the two most common bacterial isolates. S equi is primarily a disease of the lymph nodes and upper respiratory tract. Viral agents can compromise the natural defense mechanisms of the respiratory tract, resulting in secondary bacterial infections. The acute respiratory distress syndrome...
Buergelt CD, Hines SA, Cantor G, Stirk A, Wilson JH.Proliferative and fibrosing interstitial lung disease was diagnosed in 20 horses submitted for necropsy between 1982 and 1985. Most of the horses were foals ranging from 3 days to 6 months in age. Six adult horses were affected. The macroscopic and microscopic characteristics of the lesions consisted of proliferative interstitial pneumonia and were similar to those of atypical interstitial pneumonia of ruminants. Based on morphologic features of the lesions, a toxic etiology is suspected for the induction of this naturally acquired primary equine lung disorder, but could not be specifically di...
Preziuso S, Pinho MD, Attili AR, Melo-Cristino J, Acke E, Midwinter AC, Cuteri V, Ramirez M.Streptococcus dysgalactiae subsp. equisimilis (SDSE) can be severely pathogenic in humans and is increasingly isolated from horses with respiratory, reproductive or other diseases, although it is often considered a commensal bacterium. Here a PCR protocol is described for identifying SDSE recovered from humans. A multiplex PCR targeting the 16S rRNA and the streptokinase precursor gene has been optimized for differentiating between SDSE strains isolated from humans and those isolated from horses. Previously, the sequence of the streptokinase precursor gene of SDSE recovered from horses has bee...
Dunkel B, Dolente B, Boston RC.Few reports exist in the veterinary medical literature describing clinical and pathological findings resembling conditions described as (ALI) and acute respiratory distress syndrome (ARDS) in man. Objective: To document history, clinical, laboratory and diagnostic findings, treatment and outcome of foals age 1-12 months diagnosed with ALI/ARDS at a referral hospital. Methods: Medical records, including radiographic, cytological, microbiological, serological and post mortem findings, were reviewed in a retrospective manner to identify foals with acute onset of respiratory distress, a partial pr...
Shaw SD, Norman TE, Arnold CE, Coleman MC.The objective of this case series was to characterize the population, case presentations, and outcomes of 28 equids diagnosed with cleft palate over a 25-year period. The incidence of cleft palate was 0.04%. The median age at presentation was 2 mo (range: 1 d to 3 y). Fifty percent of the animals were < 2 mo old, 21% were ≥ 2 mo but < 1 y old, and 29% were 1 y of age or older. Males and females were nearly equally represented. Short-term outcomes included euthanasia in 50%, surgical repair in 11%, supportive care in 4%, and no treatment in 32% of cases; 46% of the animals survived to d...
Hines SA, Kanaly ST, Byrne BA, Palmer GH.Rhodococcal pneumonia is an important, life threatening disease of foals and immunosuppressed humans. Increased knowledge of the mechanisms of protective immunity are required in order to develop an effective immunoprophylaxis strategy for horses and immunotherapeutic regiments for people. Both humoral and cellular components of the immune system may be involved in immune clearance of R. equi. The susceptibility of foals less than 4-6 months of age is postulated to reflect waning maternal antibody, and passive transfer of hyperimmune plasma can provide protection on endemic farms. However, eff...
Passamonti F, Vardi DM, Stefanetti V, Marenzoni ML, Prato S, Cévese P, Coletti M, Pepe M, Casagrande Proietti P, Olea-Popelka F.Early diagnosis and prevention of Rhodococcus equi pneumonia in foals represent important goals for equine clinicians. Recent protocols for diagnosis and treatment of Rhodococcosis in foals typically rely on a multimodal approach based on sonographic evidence suggestive of pyogranulomas, sonographic abscess scores and laboratory findings including plasma fibrinogen concentrations, blood biochemistry testing and platelet and leukocyte counts. The aim of this study was to assess the utility of weekly testing of serum amyloid A (SAA) and plasma fibrinogen concentrations in foals to achieve early ...
Muranaka M, Yamanaka T, Katayama Y, Niwa H, Oku K, Matsumura T, Oyamada T.To investigate the pathology of equine influenza, necropsy of 7 horses experimentally infected with equine influenza A virus (EIV) subtype H3N8 was conducted on post-infection days (PID) 2, 3, 7, and 14. Histopathologically, rhinitis or tracheitis including epithelial degeneration or necrosis with loss of ciliated epithelia and a reduction in goblet cell numbers, was observed in the respiratory tracts on PIDs 2 and 3. Epithelial hyperplasia or squamous metaplasia and suppurative bronchopneumonia with proliferation of type II pneumocytes were observed on PIDs 7 and 14. Viral antigen was detecte...
Sanz MG, Oliveira AF, Page A, Horohov DW.Rhodococcus equi is the most common cause of pneumonia in young foals. A vaccine is not available and the use of R equi-specific hyperimmune plasma (HIP) is common. Despite its widespread use, the efficacy of HIP in preventing disease remains controversial. The objectives of this study were (1) to evaluate the virulence associate protein A (VapA)-specific IgG and IgG subclasses in commercially available R equi HIP and (2) to evaluate serum VapA-specific IgG and IgG subclasses in foals following administration of commercial R equi HIP. Three different lots from four commercial R equi HIP were s...
Reimer JM, Reef VB, Spencer PA.The medical records of 83 horses with pleuropneumonia and/or pulmonary abscessation, in which thoracic sonography was used, were reviewed. The sonograms of these horses were reviewed retrospectively for free gas echoes within pleural or abscess fluid. Anaerobic infection was confirmed in 27 horses, and gas echoes were observed in 21 horses. There was a significant (P less than 0.001) correlation between the observation of gas echoes and anaerobic infection in horses with pleuropneumonia and/or pulmonary abscessation. A foul odor to the breath or pleural fluid was significantly (P less than 0.0...
Flaminio MJ, Nydam DV, Marquis H, Matychak MB, Giguère S.Susceptibility of foals to Rhodococcus equi pneumonia is exclusive to the first few months of life. The objective of this study was to investigate the immediate immunologic response of foal and adult horse antigen-presenting cells (APCs) upon infection with R. equi. We measured the activation of the antigen-presenting major histocompatibility complex (MHC) class II molecule, costimulatory molecules CD40 and CD86, the cytokine interleukin-12 (IL-12), and the transcriptional factor interferon regulatory factor 1 (IRF-1) in monocyte-derived macrophages (mMOs) and dendritic cells (mDCs) of adult h...
Rakowska A, Cywinska A, Witkowski L.The aim of this review was to summarize studies on equine rhodococcosis over the last decade. For many years has remained one of the major health challenges in the equine breeding industry worldwide. Recently, many novel approaches and ideas have been described and some of them were initially implemented into the clinical practice. This study reviews a variety of new information about neonatal susceptibility, clinical appearance, considered and applied diagnostic procedures and treatment alternatives, factors limiting accurate prognosis, ideas regarding environmental management and prophylax...
Takai S, Kawazu S, Tsubaki S.Humoral immune response to Rhodococcus equi in experimentally infected foals was studied with the enzyme-linked immunosorbent assay (ELISA) method. Class-specific antibodies were measured by ELISA in the sera of foals after intratracheal or oral inoculation with R. equi ATCC 6939 or T 48 and in the lung washings of a foal after intratracheal inoculation or of normal horses. After intratracheal or oral inoculation with R. equi, serum antibodies were first detected in immunoglobulin G (IgG) followed by IgM and IgA classes, but significant levels of IgM and IgA developed only in the foal infected...
Ainsworth DM, Weldon AD, Beck KA, Rowland PH.Five 3-month-old foals presenting with fever and respiratory disease were found to have pulmonary abscesses with patchy to diffuse alveolar and interstitial pneumonia on post-mortem examination. All affected foals had evidence of Rhodococcus equi infection and had few to abundant Pneumocystis carinii cysts in the sections of affected lung. Of the 5 foals examined radiographically, 3 had a distinct reticulonodular (miliary) pattern which may aid in the ante-mortem diagnosis of P. carinii pneumonia (PCP). Leukocyte counts of foals with PCP were significantly greater than in the control group of ...
Passamonti F, Vardi DM, Stefanetti V, Marenzoni ML, Prato S, Cévese P, Coletti M, Pepe M, Casagrande Proietti P, Olea-Popelka F.Early diagnosis and prevention of Rhodococcus equi pneumonia in foals represent important goals for equine clinicians. Recent protocols for diagnosis and treatment of Rhodococcosis in foals typically rely on a multimodal approach based on sonographic evidence suggestive of pyogranulomas, sonographic abscess scores and laboratory findings including plasma fibrinogen concentrations, blood biochemistry testing and platelet and leukocyte counts. The aim of this study was to assess the utility of weekly testing of serum amyloid A (SAA) and plasma fibrinogen concentrations in foals to achieve early ...
Feige K, Schwarzwald C, Fürst A, Kaser-Hotz B.The major purpose of this investigation was to describe the causes, possible complications, and prognoses of horses with esophageal obstruction. Of 34 cases presenting with esophageal obstruction, 28 cases were due to impaction of ingesta. Obstruction due to pre-existing esophageal disease occurred in 4 horses with megaesophagus, in 1 horse with stricture in the upper third of the esophagus, and in 1 horse with esophageal diverticulum. There was no significant difference in the contamination of the trachea between horses that subsequently developed aspiration pneumonia and those that did not. ...
Prescott JF, Ogilvie TH, Markham RJ.A lymphocyte stimulation test using antigens of Corynebacterium equi was used to compare the response of peripheral blood lymphocytes from foals with C equi pneumonia with those of clinically normal foals and adult horses. The test clearly distinguished infected foals from normal foals when tested in animals less than or equal to 2 months old. After the 2nd month, stimulation response from individual normal foals sometimes exceed those from infected foals, but mean stimulation response to C equi antigens was significantly (P less than 0.025) greater in 3- to 5-month-old infected foals when com...
Chaffin MK, Cohen ND, Martens RJ, Edwards RF, Nevill M, Smith R.Rhodococcus equi causes severe pyogranulomatous pneumonia in foals and in immunocompromised people. In mice, both CD4+ and CD8+ T lymphocytes contribute to host defense against R. equi, but CD4+ T lymphocytes are required for pulmonary clearance of the bacteria. In this prospective study of 208 foals at two equine breeding farms with endemic R. equi infections, we collected peripheral blood samples at 2 and 4 weeks of age and at the time of diagnosis of R. equi pneumonia. Samples were analyzed for concentrations of total and differential leukocytes, EqCD4+ and EqCD8+ T lymphocytes, and B lymph...
Back H, Kendall A, Grandón R, Ullman K, Treiberg-Berndtsson L, Ståhl K, Pringle J.A standardbred gelding with a history of 10 days pyrexia and lethargy was referred to the Equine Hospital at the Swedish University of Agricultural Sciences in Uppsala, Sweden.The horse had tachypnea with increased respiratory effort and was in thin body condition. Laboratory findings included leukocytosis, hyperfibrinogenemia and hypoxemia. Thoracic radiographs showed signs of pneumonia with a multifocal nodular pattern, which in combination with lung biopsy findings indicated Equine Multinodular Pulmonary Fibrosis (EMPF). EMPF is a recently described disease in adult horses with clinical s...
Jacks S, Giguère S, Prescott JF.Rhodococcus equi is a facultative intracellular pathogen that causes pneumonia in foals but does not induce disease in adult horses. Virulence of R. equi depends on the presence of a large plasmid, which encodes a family of seven virulence-associated proteins (VapA and VapC to VapH). Eradication of R. equi from the lungs depends on gamma interferon (IFN-gamma) production by T lymphocytes. The objectives of the present study were to determine the relative in vivo expression of the vap genes of R. equi in the lungs of infected foals, to determine the recall response of bronchial lymph node (BLN)...
Higuchi T, Arakawa T, Hashikura S, Inui T, Senba H, Takai S.The effect on foals of prophylactic administration of hyperimmune plasma to prevent R. equi infection was investigated on three farms at which R. equi infection was endemic. Sixteen foals between 10 and 39 days of age were intravenously given 1-21 of hyperimmune plasma. ELISA antibody titres against R. equi were significantly increased and maintained at high levels for over 30 days in most of the recipient foals. The prevalence of R. equi infection was 6.3% (1/16) in the foals that received the immune plasma, and 26.3% (5/19) in the control foals not given the immune plasma on the three farms....
Takai S, Iimori S, Tsubaki S.Quantitative culture of Corynebacterium (Rhodococcus) equi from feces of 17 foals on a farm (A) with an endemic C. equi infection problem and 26 foals on a farm (B) without the disease in the past decade was done with a selective medium at weekly or monthly intervals from April to August of 1984. Corynebacterium equi was observed in the feces of 16 of 17 foals on farm A, and 19 of 26 foals on farm B. The mean viable count of C. equi in one gram of feces was 4.1 +/- 3.7 (log10) on farm A, and 3.9 +/- 3.4 (log10) on farm B. Corynebacterium equi was recovered from feces of foals as young as two w...
Raisis AL, Hodgson JL, Hodgson DR.Equine neonatal septicaemia was confirmed in 24 foals hospitalised at the Rural Veterinary Centre between 1989 and 1992 with suspected septicaemia. Septicaemia was confirmed by culture of bacteria from blood of live foals and tissues obtained at necropsy of foals that died or were euthanased. Pathogenic bacteria isolated were predominantly Enterobacteriaceae (including Escherichia coli and Salmonella serovars) and Actinobacillus equuli. Clinical manifestations of septicaemia included signs of depression, dehydration, abnormalities in body temperature and manifestations of localised infection i...
Racklyeft DJ, Raidal S, Love DN.To review relevant literature on factors associated with the development of equine pleuropneumonia. Methods: A review of the literature using a range of databases including Current Contents, Medline, ChemAbstracts, Biological Abstracts and CAB and a comprehensive search strategy which involved use of keywords, author and subject category searches. Additional sources included review of articles cited by key accumulated references. Results: Since the early years of this century, many of the "gaps" in our knowledge of the pathogenesis of this disease have been filled. We now know that equine pleu...
Giguère S, Berghaus LJ, Miller CD.Despite the paucity of data available, stall-side serum amyloid (SAA) assays are commonly used to make diagnostic and treatment decisions in foals with bronchopneumonia. Objective: Measurement of SAA concentrations can accurately differentiate pneumonic from healthy foals. Methods: Fifty-four pneumonic foals between 3 weeks and 5 months of age were compared to 44 healthy controls. In addition, 47 foals on a farm endemic for R. equi infections were studied. Methods: Serum samples were collected from pneumonic foals at hospital admission. Foals were categorized as having pneumonia caused by R. e...
