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.
Gurel V, Lambert K, Page AE, Loynachan AT, Huges K, Timoney JF, Fettinger M, Horohov DW, McMichael J.The addition of streptolysin-O (SLO) to the standard antibiotics regimen was shown to be superior to antibiotics alone after experimental infection of foals with Rhodoccocus equi (R. equi). The objective of this study is to investigate this response by determining the site-specific expression of extracellular matrix (ECM) and inflammatory response genes in biopsy samples taken from three distinct lung regions of the infected foals. Twenty-four foals were challenged by intrabronchial instillation of R. equi and assigned to four treatment groups: SLO/antibiotics adjunct therapy, antibiotics-only...
Jennings SH, Wise AG, Nickeleit V, Maes RK, Cianciolo RE, Del Piero F, Law JM, Kim Y, McCalla AC, Breuhaus BA, Roberts MC, Linder KE.Polyomaviruses produce latent and asymptomatic infections in many species, but productive and lytic infections are rare. In immunocompromised humans, polyomaviruses can cause tubulointerstitial nephritis, demyelination, or meningoencephalitis in the central nervous system and interstitial pneumonia. This report describes 2 Standardbred horses with tubular necrosis and tubulointerstitial nephritis associated with productive equine polyomavirus infection that resembles BK polyomavirus nephropathy in immunocompromised humans.
Cohen ND, Chaffin MK, Kuskie KR, Syndergaard MK, Blodgett GP, Takai S.To determine whether the concentrations of airborne virulent Rhodococcus equi in stalls housing foals during the first 2 weeks after birth are associated with subsequent development of R equi pneumonia in those foals. Methods: Air samples collected from foaling stalls and holding pens in which foals were housed during the first 2 weeks after birth. Methods: At a breeding farm in Texas, air samples (500 L each) were collected (January through May 2011) from stalls and pens in which 121 foals were housed on day 1 and on days 4, 7, and 14 after birth. For each sample, the concentration of airborn...
Chesnel MA, Aprea F, Clutton RE.A traumatic pneumothorax and severe hemorrhage were present in a mare with a large thoracic wall defect, lung perforation, and multiple rib fractures. General anesthesia was induced to allow surgical exploration. We describe the anesthetic technique, and discuss the management of the ventilatory, hemodynamic, and metabolic disturbances encountered. Gestion de l’anesthésie générale d’un cheval avec un pneumothorax d’origine traumatique. Nous décrivons le cas d’une jument présentée avec un important déficit de la paroi thoracique d’origine traumatique, une perforation pulmonaire...
Giguère S, Jordan LM, Glass K, Cohen ND.Isolation of multiple bacterial species is common in foals with Rhodococcus equi pneumonia. Objective: There is no association between isolation of other microorganisms and outcome. Methods: 155 foals with pneumonia caused by R. equi. Methods: Case records of foals diagnosed with R. equi pneumonia based on culture of the respiratory tract were reviewed at 2 referral hospitals (University of Florida [UF] and Texas A&M University [TAMU]). Results: R. equi was cultured from a tracheobronchial aspirate (TBA) in 115 foals and from lung tissue in 38 foals. Survival was significantly higher at UF...
Dunkel B, Corley KT, Johnson AL, Witte TH, Leitch M, Marr CM, Weller R.Pneumocephalus is occasionally encountered in horses but poorly described in the literature. The study aimed to describe historical, clinical and diagnostic imaging findings and outcome in horses to increase the awareness and recognition of the condition amongst equine practitioners, allowing appropriate management of these cases. Cases of pneumocephalus from 4 participating institutions were identified and case details extracted from the medical records. Five cases of pneumocephalus were identified. Head trauma with suspected or confirmed fractures of the sinuses was the underlying cause in 4...
Villarino N, Martín-Jiménez T.Macrolides are used for treatment of pneumonia and extrapulmonary conditions caused by Rhodococcus equi. In foals, macrolides have an extraordinary capacity to accumulate in different lung tissue compartments. These drugs show unique pharmacokinetic features such as rapid and extensive distribution and long persistence in pulmonary epithelial lining fluid (PELF) and bronchoalveolar lavage (BAL) cells from foals. This article reviews the pharmacokinetic characteristics of erythromycin, azithromycin, clarithromycin, tulathromycin, telithromycin, gamithromycin, and tilmicosin in foals, with empha...
Po E, Williams C, Muscatello G, Celi P.This study reports preliminary data on systemic and local biomarkers of oxidative stress (OS) in Thoroughbred foals. Blood and exhaled breath condensate (EBC) were sampled from 13 foals on two farms. Values of reactive oxygen metabolites (d-ROMs), biological antioxidant potential (BAP), antioxidant barrier (OXY-ads), thiol antioxidant barrier (SHp) and advanced oxidation protein products (AOPPs) were determined in blood, while EBC samples were assayed for hydrogen peroxide (H(2)O(2)) levels. Systemic and local OS biomarkers did not differ between farms and gender. Increased oxidative stress in...
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...
Bidaud P, Hébert L, Barbey C, Appourchaux AC, Torelli R, Sanguinetti M, Laugier C, Petry S.Rhodococcus equi is one of the most widespread causes of disease in foals aged from 1 to 6 months. R. equi possesses antioxidant defense mechanisms to protect it from reactive oxygen metabolites such as hydrogen peroxide (H(2)O(2)) generated during the respiratory burst of phagocytic cells. These defense mechanisms include enzymes such as catalase, which detoxify hydrogen peroxide. Recently, an analysis of the R. equi 103 genome sequence revealed the presence of four potential catalase genes. We first constructed ΔkatA-, ΔkatB-, ΔkatC-and ΔkatD-deficient mutants to study the ability of R. ...
Rendle DI, Armstrong SK, Hughes KJ.This report documents the treatment of a case of chronic pleuropneumonia in a 3-year-old Thoroughbred gelding. A recombinant tissue plasminogen activator (tenecteplase) and a recombinant deoxyribonucleic acidase (alphadornase) were infused into the pleural cavity as adjunctive therapy in the early stages of treatment. Instillation of fibrinolytic drugs was associated with a subjective reduction in the amount of fibrin deposition and decreased fluid accumulation within the pleural cavities. Fibrinolytic therapy may be a useful adjunctive therapy in selected cases of intrapleural disease in hors...
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...
Giguère S, Roberts GD.Our objective was to characterize the association between types of radiographic findings and outcome in foals with pneumonia caused by Rhodococcus equi. Admission lateral thoracic radiographs of 62 foals with culture-confirmed R. equi pneumonia were reviewed retrospectively. A scoring system was developed to individually assess the severity of alveolar pattern, interstitial pattern, tracheobronchial lymphadenopathy, pleural effusion, and the number of nodular opacities and cavitary lesions. Individual scores were added to obtain a total radiographic score ranging from 0 (normal) to 22. Forty-t...
Holcombe SJ, Hurcombe SD, Barr BS, Schott HC.Dysphagia due to pharyngeal dysfunction occurs in human neonates and is associated with prematurity and hypoxic episodes. This syndrome probably occurs in neonatal foals but has not been reported. Objective: The objectives of this study were to describe 1) a series of neonatal foals with dysphagia due to pharyngeal dysfunction; 2) the progression, treatment and resolution of the dysphagia; 3) the comorbidities; and 4) the prognosis for life and athleticism for affected foals. Methods: Records from 3 referral equine hospitals were reviewed from neonatal foals with dysphagia of pharyngeal origin...
Chicken C, Muscatello G, Freestone J, Anderson GA, Browning GF, Gilkerson JR.Disease caused by Rhodococcus equi is a significant burden to the horse breeding industry worldwide. Early detection of rhodococcal pneumonia, albeit important to minimise treatment costs, is difficult because of the insidious nature of the disease and the lack of definitive diagnostic tests. Objective: To investigate air sampling from the breathing zone of neonatal foals as a predictor of subsequent rhodococcal pneumonia. Methods: Air samples were collected from the breathing zone of 53 neonatal foals (age ≤10 days) and again at the time of routine ultrasonographic screening for R. equi p...
Bordin AI, Liu M, Nerren JR, Buntain SL, Brake CN, Kogut MH, Cohen ND.Rhodococcus equi is an intracellular bacterium that causes pneumonia in foals and immunocompromised adult horses. Evidence exists that foals become infected with R. equi early in life, a period when innate immune responses are critically important for protection against infection. Neutrophils are innate immune cells that play a key role in defense against this bacterium. Enhancing neutrophil function during early life could thus help to protect foals against R. equi infection. The objective of our study was to determine whether in vitro incubation with the TLR9 agonist CpG 2142 would enhance d...
Giguère S, Cohen ND, Chaffin MK, Slovis NM, Hondalus MK, Hines SA, Prescott JF.Rhodococcus equi, a gram-positive facultative intracellular pathogen, is one of the most common causes of pneumonia in foals. Although R. equi can be cultured from the environment of virtually all horse farms, the clinical disease in foals is endemic at some farms, sporadic at others, and unrecognized at many. On farms where the disease is endemic, costs associated with morbidity and mortality attributable to R. equi may be very high. The purpose of this consensus statement is to provide recommendations regarding the diagnosis, treatment, control, and prevention of infections caused by R. equi...
Muscatello G.Various challenges face clinicians and farm managers in diagnosing, treating and preventing Rhodococcus equi pneumonia. The use of ultrasound imaging has aided in the early diagnosis of the disease, reducing treatment duration and improving therapeutic outcomes. Antimicrobial resistance in R. equi is an emerging issue that necessitates prudent antimicrobial therapy of diseased foals. Alternative methods of disease transmission, such as contagious foal-to-foal aerosol transmission, may need to be addressed to complement dust reduction environmental strategies and to minimise the overall risk of...
Dawson DR, Nydam DV, Price CT, Graham JE, Cynamon MH, Divers TJ, Felippe MJ.To investigate the effect of opsonization of Rhodococcus equi with R. equi-specific antibodies in plasma on bacterial viability and phagocyte activation in a cell culture model of infection. Methods: Neutrophils and monocyte-derived macrophages from 6 healthy 1-week-old foals and 1 adult horse. Methods: Foal and adult horse phagocytes were incubated with either opsonized or nonopsonized bacteria. Opsonization was achieved by use of plasma containing high or low concentrations of R. equi-specific antibodies. Phagocyte oxidative burst activity was measured by use of flow cytometry, and macrophag...
Goodyear A, Troyer R, Bielefeldt-Ohmann H, Dow S.The Gram-negative bacterium Burkholderia mallei causes rapidly fatal illness in equines and humans when contracted by inhalation and also has the potential to be used as a bioweapon. However, little is known regarding the early innate immune responses and signaling mechanisms required to generate protection from pneumonic B. mallei infection. We showed previously that monocyte chemoattractant protein 1 (MCP-1) was a critical chemokine required for protection from pneumonic B. mallei infection. We have now extended those studies to identify key Toll-like receptor (TLR) signaling pathways, effec...
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...
Muscatello G.Rhodococcus equi pneumonia is a worldwide infectious disease of major concern to the equine breeding industry. The disease typically manifests in foals as pyogranulomatous bronchopneumonia, resulting in significant morbidity and mortality. Inhalation of aerosolised virulent R. equi from the environment and intracellular replication within alveolar macrophages are essential components of the pathogenesis of R. equi pneumonia in the foal. Recently documented evidence of airborne transmission between foals indicates the potential for an alternative contagious route of disease transmission. In the...
Giguère S, Cohen ND, Chaffin MK, Hines SA, Hondalus MK, Prescott JF, Slovis NM.Pneumonia is a major cause of disease and death in foals. Rhodococcus equi, a gram-positive facultative intracellular pathogen, is a common cause of pneumonia in foals. This article reviews the clinical manifestations of infection caused by R. equi in foals and summarizes current knowledge regarding mechanisms of virulence of, and immunity to, R. equi. A complementary consensus statement providing recommendations for the diagnosis, treatment, control, and prevention of infections caused by R. equi in foals can be found in the same issue of the Journal.
Graubner C, Gerber V, Imhasly A, Gorgas D, Koch C.Three horses (age 17 - 23 years) were referred to the equine clinic of the University of Berne due to colic, fever, tachycardia and tachypnea. All horses showed pleural effusion. Clinical findings in 2 of the horses were highly suggestive of an intra-thoracic esophageal perforation. Severe septic pleuropneumonia without suspicion of an esophageal lesion was diagnosed in the 3rd horse. In addition, an 11 year old stallion was referred to the equine clinic for treatment of a presumptive large colon impaction. The horse was given laxatives after nasogastric intubation. Subsequent dramatic clinica...
Venner M, Rödiger A, Laemmer M, Giguère S.Mass antimicrobial treatment of foals with small ultrasonographic pulmonary lesions is common on farms with endemic disease caused by Rhodococcus equi. The objectives of this study were to compare the relative efficacy of three antimicrobial protocols for the treatment of pulmonary abscesses on a farm with endemic infections caused by R. equi and to determine the frequency of spontaneous resolution of subclinical pulmonary lesions. Foals with ultrasonographic evidence of pulmonary abscesses ≥ 1.0 cm in diameter (n=128) were randomly allocated to one of four equal treatment groups. Animals wi...
van der Geize R, Grommen AW, Hessels GI, Jacobs AA, Dijkhuizen L.Rhodococcus equi causes fatal pyogranulomatous pneumonia in foals and immunocompromised animals and humans. Despite its importance, there is currently no effective vaccine against the disease. The actinobacteria R. equi and the human pathogen Mycobacterium tuberculosis are related, and both cause pulmonary diseases. Recently, we have shown that essential steps in the cholesterol catabolic pathway are involved in the pathogenicity of M. tuberculosis. Bioinformatic analysis revealed the presence of a similar cholesterol catabolic gene cluster in R. equi. Orthologs of predicted M. tuberculosis vi...
Willingham-Lane JM, Berghaus LJ, Berghaus RD, Hart KA, Giguère S. is a leading cause of severe pneumonia in foals. Standard treatment is dual antimicrobial therapy with a macrolide and rifampin, but the emergence of macrolide- and rifampin-resistant isolates is an increasing problem. The objective of this study was to determine the effect of macrolide and/or rifampin resistance on fitness of Three unique isogenic sets were created, each consisting of four strains, as follows: a susceptible parent isolate, strains resistant to macrolides or rifampin, and a dual macrolide- and rifampin-resistant strain. Each isogenic set's bacterial growth curve was genera...
Lakritz J, Wilson WD, Berry CR, Schrenzel MD, Carlson GP, Madigan JE.Twenty-three foals, between 1 and 7 months old, with signs of acute respiratory distress, were examined at the Veterinary Medical Teaching Hospital (VMTH), University of California, Davis, between 1984 and 1989. Characteristic features included sudden onset of severe respiratory distress and tachypnea, cyanosis unresponsive to nasal oxygen, pyrexia, hypoxemia, hypercapneic respiratory acidosis, poor response to treatment, and histopathologic lesions of bronchiolitis and bronchointerstitial pneumonia. Seven of the 23 foals were normal before the onset of respiratory distress, 3 foals were found...
Takiguchi M, Fujinaga T, Naiki M, Mizuno S, Otomo K.C-reactive protein (CRP) was isolated from equine serum by use of calcium-dependent affinity chromatography conjugated pneumococcal C-polysaccharide, anion exchange chromatography, and gel filtration. It was identified as genuine CRP by its immunochemical cross-reactivity with anti-human CRP, its homology with human CRP in amino acid composition, and its pentameric structure as revealed by electron microscopy. Purified equine CRP had a molecular weight of approximately 118,000 and was composed of 5 identical, nonglycosylated and noncovalently associated subunits with molecular weight of approx...
Leclere M, Magdesian KG, Kass PH, Pusterla N, Rhodes DM.The purpose of this study was to compare the clinical, microbiological, radiological, haematological and cytological features of foals with pneumonia caused by Rhodococcus equi infection and with other bacteria, in order to provide markers for early diagnosis and treatment. A retrospective study of 113 cases of bacterial pneumonia was undertaken. Although there was considerable overlap in the affected populations, foals with R. equi pneumonia were significantly younger and had higher respiratory rates. Radiological evidence of thoracic abscessation had a sensitivity of 71% and a specificity of...
Sanz MG.Foals become infected shortly after birth; most develop subclinical pneumonia and 20% to 30% develop clinical pneumonia that requires treatment. It is now well established that the combination of screening programs based on thoracic ultrasonography and treatment of subclinical foals with antimicrobials has led to the development of resistant Rhodococcus equi strains. Thus, targeted treatment programs are needed. Administration of R equi-specific hyperimmune plasma shortly after birth is beneficial as foals develop less severe pneumonia but does not seem to prevent infection. This article provi...
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...
McQueen CM, Dindot SV, Foster MJ, Cohen ND.Rhodococcus equi pneumonia is a major cause of morbidity and mortality in neonatal foals. Much effort has been made to identify preventative measures and new treatments for R. equi with limited success. With a growing focus in the medical community on understanding the genetic basis of disease susceptibility, investigators have begun to evaluate the interaction of the genetics of the foal with R. equi. This review describes past efforts to understand the genetic basis underlying R. equi susceptibility and tolerance. It also highlights the genetic technology available to study horses and des...
De La Peña-Moctezuma A, Prescott JF, Goodfellow M.Four isolates of Rhodococcus equi, from pneumonic foals, and containing the 85 kb virulence plasmid, a porcine isolate containing an 80 kb plasmid, and their plasmid cured derivatives, were examined for 239 phenotypic properties in an attempt to find characters other than the virulence-associated protein (VapA) which might be encoded by the virulence plasmid in organisms grown at 37 degrees C. Tests chosen included those which have previously given variable results for R. equi isolates, since such variability might be attributed to plasmid curing, and characteristics which have been described ...
Sellon DC, Walker K, Suyemoto M, Altier C.To evaluate the ability of nucleic acid amplification techniques to detect Rhodococcus equi in equine buffy coat, blood, and tracheal wash fluid and to differentiate between virulent and avirulent strains of the bacteria. Methods: Blood anticoagulated with EDTA and tracheal wash fluid from healthy horses. Methods: Logarithmic dilutions of virulent and avirulent strains of R equi were added to equine buffy coat and tracheal wash fluid samples. The DNA was extracted and amplified by polymerase chain reaction (PCR), using primers specific for the 16S ribosomal subunit gene and the virulence plasm...
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...
Prescott JF, Sweeney CR.Combined antimicrobial drug treatment was recommended for foals with Corynebacterium equi pneumonia. The preferred combination is orally administered erythromycin estolate (25 mg/kg of body weight, QID) plus rifampin (10 mg/kg, BID). Erythromycin estolate also can be combined for synergistic effect with sodium benzyl penicillin given IV (100,000 IU/kg, QID) or with ampicillin given IV (11 to 15 mg/kg, QID). A third choice is sodium benzyl penicillin IV with gentamicin IM (2.2 mg/kg, TID) or with kanamycin IM (10 mg/kg, QID). Gentamicin should be combined with penicillin G or ampicillin and not...
Hooper PT, Williamson MM.The most important clinical and pathological manifestation of Hendra virus infection in horses and humans is that of severe interstitial pneumonia caused by viral infection of small blood vessels. The virus is also capable of causing nervous disease. Hendra virus is not contagious in horses and is spread by close contact with body fluids, such as froth from infected lungs. Diagnosis should be based on the laboratory examination of blood, lung, kidney, spleen, and, if nervous signs are present, also of the brain. Evidence of infection with the more recently identified and related Nipah virus wa...
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...
Carvallo FR, Uzal FA, Diab SS, Hill AE, Arthur RM.Respiratory diseases have a major impact on racehorses in training and are often cited as the second most common reason of horses failing to perform. Cases were submitted by the California Horse Racing Board to the California Animal Health and Food Safety laboratory for postmortem examination between January 1, 2005 and December 31, 2014. We determined the demographics of racehorses with fatal pneumonia, characterized the pathologic findings in animals with a postmortem diagnosis of respiratory infection, and determined the most significant pathogens associated with lower respiratory tract dis...
Woolcock JB, Mutimer MD, Bowles PM.Normal horses of all ages regularly show evidence of having responded immunologically to R. equi, thus adding serological support to epidemiological evidence that this organism is a normal intestinal inhabitant. More animals from "diseased" farms show a stronger antibody response when compared with foals from "healthy" farms. Various serological tests have been used to detect evidence of infection and to relate antibody level to severity of disease. Anti-R. equi IgG antibody levels, as measured by ELISA, are raised significantly during natural infection. Clinical severity of pneumonia can be c...
Chaffin MK, Cohen ND, Martens RJ.To determine whether foal management practices, environmental management, and preventative health practices are risk factors for development of Rhodococcus equi pneumonia in foals. Methods: Prospective matched case-control study. Methods: 2,764 foals on 64 equine breeding farms with 9,991 horses. Methods: During 1997, participating veterinarians completed paired data collection forms for comparison; 1 for an affected farm (containing > or = 1 foal with pneumonia caused by R equi) and 1 for a control farm. Information collected pertained to stabling facilities, environmental management, foal hu...
Berlin S, Randow T, Scheuch E, Grube M, Venner M, Siegmund W.The long-acting azalide antibiotic gamithromycin is marketed for intramuscular treatment of bovine and swine infections. Off-label use in foals leads to severe local lesions likely caused by hyperosmolality of the injected solution. We provide evidence from a pharmacokinetic study in 10 warm-blooded healthy foals for intravenous bolus injection of gamithromycin diluted in distilled water to be a safe and well tolerated alternative. By intravenous dosing, markedly higher plasma exposure and better penetration into bronchoalveolar lavage cells but lower distribution into epithelial lining fluid ...
Ito S, Hobo S, Eto D, Sato H.To evaluate a hypothese that use of bronchoalveolar lavage (BAL) for early treatment of pneumonia would improve their prognosis by reducing bacterial numbers and excessive numbers of neutrophils in the lung, initial experiences with BAL in the diagnosis and treatment of pneumonia were performed in 36 racehorses that became ill within 24 hr of long distance travel (1,200-1,600 km, 26-32 hr) by road. Comparisons were made of the outcomes of the 36 horses and those of 42 horses (81.0% recovered, 50.0% returned to racing) treated for transport associated pneumonia without BAL. The total amount of ...
Takai S, Henton MM, Picard JA, Guthrie AJ, Fukushi H, Sugimoto C.The prevalence of virulent Rhodococcus equi in soil isolates from two horse farms in South Africa and nine clinical isolates from six foals, a foal foetus, a dog, and a monkey was investigated. The isolates were tested for the presence of virulence plasmid DNA and 15- to 17-kDa antigens by immunoblotting. Rhodococcus equi was isolated from almost all of the soil samples obtained from the two farms with 5.0 x 10(1) to 3.3 x 10(4) colony forming units per gram of soil. Virulent R. equi was isolated from three soil samples from one of the farms and appeared in 3.8% (three of 80 isolates), but not...
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. ...
Higgins C, Huber L.Rhodococcus equi, a gram-positive facultative intracellular pathogen and a soil saprophyte, is one of the most common causes of pneumonia in young foals. It poses a threat to the economy in endemic horse-breeding farms and to animal welfare annually. Many farms use thoracic ultrasonographic screening and antimicrobial treatment of subclinically affected foals as a preventive measure against severe R. equi infections. The wide use antimicrobials to treat subclinically affected foals has contributed to the emergence of multidrug resistant (MDR)-R. equi in both clinical isolates from sick foals a...
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...
Haites RE, Muscatello G, Begg AP, Browning GF.The prevalence of the plasmid-encoded virulence-associated gene (vapA) of Rhodococcus equi, as determined by PCR, was found to be 98% in isolates from 154 foals with pneumonia, confirming the strong association of vapA with virulence. The vapA genes from 60 representative isolates were compared by digestion with the restriction endonuclease HinfI, and no evidence of sequence variation was detected.
Whitfield-Cargile CM, Cohen ND, Suchodolski J, Chaffin MK, McQueen CM, Arnold CE, Dowd SE, Blodgett GP.In equids, susceptibility to disease caused by Rhodococcus equi occurs almost exclusively in foals. This distribution might be attributable to the age-dependent maturation of immunity following birth undergone by mammalian neonates that renders them especially susceptible to infectious diseases. Expansion and diversification of the neonatal microbiome contribute to development of immunity in the gut. Moreover, diminished diversity of the gastrointestinal microbiome has been associated with risk of infections and immune dysregulation. We thus hypothesized that varying composition or reduced div...
Lavoie JP, Fiset L, Laverty S.A retrospective study of 40 horses with primary lung abscesses without pleuropneumonia showed that lung abscesses occurred predominantly in young horses, usually in foals aged < or = 6 months. Hyperfibrinogenaemia was present in all but 2 horses, and other common clinical and haematological findings were hyperthermia, tachycardia, polypnoea, and neutrophilic leucocytosis. The most common bacterial species isolated from transtracheal aspirates were Streptococcus zooepidemicus (20/34) and Rhodococcus equi (13/34). Most horses (23/27) discharged from the hospital were long term survivors. Of t...
Bidaud P, Hébert L, Barbey C, Appourchaux AC, Torelli R, Sanguinetti M, Laugier C, Petry S.Rhodococcus equi is one of the most widespread causes of disease in foals aged from 1 to 6 months. R. equi possesses antioxidant defense mechanisms to protect it from reactive oxygen metabolites such as hydrogen peroxide (H(2)O(2)) generated during the respiratory burst of phagocytic cells. These defense mechanisms include enzymes such as catalase, which detoxify hydrogen peroxide. Recently, an analysis of the R. equi 103 genome sequence revealed the presence of four potential catalase genes. We first constructed ΔkatA-, ΔkatB-, ΔkatC-and ΔkatD-deficient mutants to study the ability of R. ...
