Horse-breeding Farms Research Articles

Features of the clinical picture of keratitis in horses with different forms of the course of the disease.

Keratitis is a common cause of eye diseases in horses, often resulting in complete loss of vision. The purpose of this article is to study the features of the clinical picture of primary and secondary keratitis in horses, depending on the form of the course of the disease. The study was conducted in 2019 at 22 private horse breeding farms. The study involved 80 horses with keratitis, which were divided into two equal groups depending on the diagnosis of primary or secondary keratitis. The effectiveness of the therapies was compared 1, 3, and 6 months after the start of treatment. Following a 1-month therapy, only a minority of horses with primary keratitis had their eye functions fully restored, the number of horses with macula was two times higher (p ≤ 0.05), the number of horses with nebula was seven times higher (p ≤ 0.001), and leukomas were reported in most of the cases ( p ≤ 0.0001). The effectiveness of the therapy for keratitis is directly related to the peculiarities of treatment and adherence to the regimen.

Efficiency of Equilume light mask on the resumption of early estrous cyclicity and ovulation in Thoroughbred mares.

Equilume light masks had no impact on hastening the resumption of estrous cyclicity in mares maintained in outdoor pastures on the mainland of Korea due to the cold weather conditions. Jeju Island is a major horse-breeding site in Korea and is warmer than the mainland during the winter season. Therefore, the primary objective of this study was to explore the efficiency of the Equilume light mask on the resumption of seasonal estrous cycles in Thoroughbred mares on Jeju Island. A total of 20 nonpregnant mares were randomly divided into the Equilume light mask (n = 9) and stable lighting (n =11) groups. The experiment was performed at seven different horse-breeding farms located on Jeju Island from November 15, 2020, to February 15, 2021. The mares were exposed to the respective lights from 16:00 to 23:00. Follicle size and uterine edema were measured by ultrasound scanning. Body condition scores (BCS) were also monitored during the experiment. Statistical analysis was conducted using the SAS and SPSS software, and p-values of < 0.05 were considered statistically significant. Two of the nine (22.2%) mares in the Equilume light mask group and three of the 11 (27.28%) mares in the stable lighting group were still cycling in December and January, which were considered as all-year-round cycling mares. On February 15, there was no difference between groups in the resumption of early seasonal estrus cycle, which was determined by follicles > 25 mm in addition to uterine edema. All mares in the Equilume light mask group and five of the eight mares (62.5%) in the stable lighting group had resumed cycling. Interestingly, six of the seven mares (87.5%) in the Equilume light mask and four of eight mares (50%) in the stable lighting group had already ovulated on February 15 (p > 0.05), as determined by the presence of a recent corpus luteum. No difference was observed in BCS and uterine edema between groups (p > 0.05). In conclusion, the Equilume light mask can be an effective approach to induce early seasonal estrus cycles of mares in Jeju Island, and it also enhances the efficiency of farm management by reducing labor.

Isolation of Rhodococcus equi from the gastrointestinal contents of earthworms (family Megascolecidae).

Rhodococcus equi was isolated from the gastrointestinal contents of earthworms (family Megascolecidae) and their surrounding soil collected from pastures of two horse-breeding farms in Aomori Prefecture, outdoor pig pens, forest in Towada campus, orange groves and forest where wild boars (Sus scrofa) are established in Tanabe, Wakayama Prefecture. The number of R. equi in the lower gastrointestinal contents of 23 earthworms collected from our campus was significantly larger than that of the upper gastrointestinal content. The mean numbers of R. equi from the gastrointestinal contents of earthworms collected from the various places were 2·3-fold to 39·7-fold more than those of the surrounding soil samples. In all, 1771 isolates from the earthworms and 489 isolates from the soil samples were tested for the presence of vapA and vapB genes using polymerase chain reaction. At the horse-breeding farm N, 9 of the 109 isolates (8·3%) from the earthworms and 7 of the 106 isolates (6·6%) from the soil samples were positive for the vapA gene. At the University's forest, one of the 250 isolates (0·4%) from the gastrointestinal contents of the earthworm was positive for the vapB gene. These results revealed that R. equi can be found in significant quantities in the gastrointestinal contents of earthworms, suggesting that they act as an accumulator of R. equi in the soil environment and as a source or reservoir of animal infection.

Ecology of microorganisms in the conditions of permafrost

The results of research into the ecology of pathogens of infectious diseases in permafrost conditions are presented. The work was carried out in laboratory conditions and horse breeding farms of the Republic of Sakha (Yakutia), located in the permafrost zone. Isolation and identification of pathogenic and conditionally pathogenic microorganisms were carried out by generally accepted methods used in microbiological practice. The survival rate of microorganisms was studied by methods of veterinary sanitation. The studies conducted showed that the survival time of some microorganisms on the objects of the environment in permafrost conditions is 2-3 times longer than the survival time of similar microorganisms in the southern and European territories of Russia and abroad. When studying microbial contamination and the survival time of microorganisms, a significant content of aerobic spore-forming bacteria (more than 2 x 106 CFU/g) in permafrost soils of Central Yakutia was established. Isolation of viable bacteria of the genus Bacillus from representatives of mammoth fauna preserved in permafrost soils (age 30-40 thousand years) proves the role of permafrost in the preservation of bacteria of the Pleistocene period. Permafrost contributes to the long-term preservation of foci and transmission factors of pathogens of infectious diseases. Isolation of pathogens of yersiniosis from the surfaces of glaciers and from wild animals indicates the danger of contamination of food during storage and consumption. The establishment of the circulation of pathogens of viral diseases among reindeer suggests the role of migratory birds in the spread of infectious diseases. The study of the epizootology of anthrax remains relevant. Knowledge of the survival time of microorganisms on the objects of the environment in the extreme conditions of the Far North and the study of the microbiota of wild animals and migratory birds are necessary to optimize antiepizootic and epidemiological measures in the prevention or elimination of infectious diseases in humans and animals.

Equine Herpesvirus Type 4 (EHV-4) Outbreak in Germany: Virological, Serological, and Molecular Investigations.

Equine herpesvirus type 4 (EHV-4) is enzootic in equine populations throughout the world. A large outbreak of EHV-4 respiratory infection occurred at a Standardbred horse-breeding farm in northern Germany in 2017. Respiratory illness was observed in a group of in-housed foals and mares, which subsequently resulted in disease outbreak. Out of 84 horses in the stud, 76 were tested and 41 horses were affected, including 20 foals, 10 stallions, and 11 mares. Virological investigations revealed the involvement of EHV-4 in all cases of respiratory illness, as confirmed by virus isolation, qPCR, and/or serological follow-up using virus neutralization test and peptide-specific ELISA. Among infected mares, 73% (8 out of 11) and their corresponding foals shed the virus at the same time. EHV-4 was successfully isolated from four animals (including one stallion and three foals), and molecular studies revealed a different restriction fragment length polymorphism (RFLP) profile in all four isolates. We determined the complete 144 kbp genome sequence of EHV-4 isolated from infected horses by next-generation sequencing and de novo assembly. Hence, EHV-4 is genetically stable in nature, different RFLP profiles, and genome sequences of the isolates, suggesting the involvement of more than one animal as a source of infection due to either true infection or reactivation from a latent state. In addition, epidemiological investigation revealed that stress caused by seasonal changes, management practices, routine equestrian activities, and exercises contributed as a multifactorial causation for disease outbreak. This study shows the importance of implementing stress alleviating measures and management practices in breeding farms in order to avoid immunosuppression and occurrence of disease.

Ways to increase the immunogenicity of inactivated vaccines against strangles

The results of the study on the specific prevention of infectious diseases in horses are presented. Methods have been developed to increase the immunogenicity of environmentally friendly vaccines against strangles, caused by the beta-hemolytic streptococcus – Sreptococcus equi. The work was carried out in laboratory conditions and horse breeding farms of the Republic of Sakha (Yakutia). The toxicity and immunogenicity of the vaccine was determined by conventional methods on young horses. Based on the study of the immunobiological reactivity of young horses, the use of immunomodulators in the development of inactivated vaccine preparations has been substantiated. Vaccines with immunomodulators were tested and registered in accordance with approved research methods for medicinal products for veterinary use. Polyribonate (polyvedrim) and culture liquid (fugate) from the bacterial strain Bacillus subtilis TNP-3 were used in the composition of vaccines as an immunomodulator. To prepare a vaccine against strangles, strains of bacteria Streptococcus equi H-34 and Streptococcus equi "H-5/1" were used, which were deposited in the Russian State Collection of Microorganism Strains of the Russian State Center for Animal Feed and Drug Standardization and Quality. After immunization with inactivated vaccines containing immunomodulators, the effectiveness of vaccines increases by 20% and reaches 90%. Vaccines increase the body's immunobiological reactivity. The most effective were the “Tabyn” vaccine and the vaccine from the Streptococcus equi strain H-5/1 with fugate, the Bacillus subtilis strain TNP-3. The polyribonate vaccine was approved in Russia (2000), the “Tabyn” vaccine is used in Kazakhstan (2018). These vaccine preparations, which ensure high antiepizootic efficacy, are environmentally friendly, since they do not contain toxic substances and antibiotics.

Association between antimicrobial treatment of subclinical pneumonia in foals and selection of macrolide- and rifampicin-resistant Rhodococcus equi strains at horse-breeding farms in central Kentucky.

To compare soil concentrations of macrolide- and rifampicin-resistant Rhodococcus equi 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 during the foaling season. 720 soil samples and 20 completed questionnaires from 20 horse-breeding farms (10 TUS farms and 10 non-TUS farms) in central Kentucky. A questionnaire was used to gather information from participating farms about their 2019 foaling season. Soil samples were collected during January, March, May, and July 2019 for bacterial culture and antimicrobial susceptibility testing to identify any isolates of MRRE. Results were compared for TUS farms versus non-TUS farms. Linear mixed-effects modeling was used to evaluate for potential associations between the soil concentration of MRRE and the use of TUS. Overall, the sum of the mean soil concentrations of MRRE was significantly higher for TUS farms (8.85 log10-transformed CFUs/g) versus non-TUS farms (7.37 log10-transformed CFUs/g). Our findings indicated that farms that use TUS to identify foals with subclinical pneumonia for antimicrobial treatment select for antimicrobial-resistant R equi strains. Because prognosis is worse for foals infected with resistant versus nonresistant strains of R equi, prudent use of antimicrobials to treat foals with subclinical pulmonary lesions attributed to R equi is recommended.

Reduced Efficacy of Fenbendazole and Pyrantel Pamoate Treatments against Intestinal Nematodes of Stud and Performance Horses.

Nematodes are an important cause of disease and loss of performance in horses. Changes in the parasitic fauna of horses have occurred in the past few decades, making cyathostomins the major parasites in adult horses, while large strongyles have become less prevalent. Parascaris spp. remains the most important parasite infecting foals and weanlings. Anthelmintic resistance is highly prevalent in cyathostomins and Parascaris spp. worldwide and it must be factored into treatment decisions. To assess anthelmintic efficacy in Northern Italy, we sampled 215 horses from 17 sport and horse-breeding farms. Fecal egg count reduction tests (FECRT) were used to assess anthelmintic efficacy. Copromicroscopic analysis was performed using MiniFLOTAC before treatment with fenbendazole, pyrantel pamoate or ivermectin, and repeated 14 days post-treatment. Strongyle-type eggs were detected in 66.91% of horses (CI95% 61.40–73.79%), while Parascaris spp. was detected in 2.79% (CI95% 1.94–5.95%). Reduced efficacy against cyathostomins was observed for fenbendazole in 55.56% of the treated animals (CI95% 41.18–69.06%), and for pyrantel pamoate in 75% of animals (CI95% 30.06–95.44%). Ground-based actions must be set in place to promote the uptake of state-of-the-art worm control plans that will prevent clinical disease while minimizing the selection pressure of resistant parasites.

Links Between Fracking and a Rare Birth Defect in Racehorses

Fracking has long been controversial for its potential to contaminate local water sources and cause damage to the environment. Dr Kathleen Mullen at Littleton Equine Medical Center in Colorado and her team have carried out novel research into how fracking in close proximity to a horse-breeding farm may be the cause of a specific birth defect in the foals born there. Her findings may be relevant to human babies and considerations of the implications of fracking on long-term health.

Entre cercas, brincadeiras e feitiços: os conflitos e as apropriações do território por crianças e jovens quilombolas

brazil has gone through a long process of colonization that still leaves violent marks in the ways of relating to quilombola communities, producing the devaluation of their cultures and knowledge. Through colonization, the lives of quilombola children and young people have become invisible in the face of scientific knowledge that uses European authors as a reference and the urban middle classes as a model. In this text, we present the results of an interventional research carried out between 2017 and 2019, with about 30 children and young people living in a quilombola community in Cafuringa, in Campos dos Goytacazes-RJ. We seek to understand how the experiences of childhood and youth are constituted from the relationships that children and young people establish with the territory, their uses and appropriations, and the modes of subjectification in the face of conflicts experienced in the community. Children take ownership of the territory through collective games held outdoors, in which they explore community spaces, and interact with the land, animals, plants and trees. For these children, these spaces can be "bewitched", "haunted", "sacred", and while fascinating, also generate fear. These ways of relating to the territory are in conflict with the agricultural produce and horse breeding farms, which consider the land as a business, and animals and plants as goods. The children's estrangement in encountering of the electric fence placed by the farm, which symbolizes the private use of the land, social inequalities, and the racial discrimination experienced in their daily lives, leads us to question the project of the overall “civilizing” project built into modernity

Assessment of Antimicrobial Susceptibility of Virulent Strains of Rhodococcus equi Isolated From Foals and Soil of Horse Breeding Farms With and Without Endemic Infections

Rhodococcus equi is an opportunistic, intracellular saprophyte that causes severe pyogranulomatous pneumonia in foals. The bacterium displays in vitro susceptibility to many antibiotics. The highest efficacy against R. equi in vitro and in vivo is achieved by using a combination of rifampicin and macrolide antibiotics. Recent years have seen an upward trend in the minimum inhibitory concentration (MIC) of rifampicin and erythromycin, suggesting increasing resistance of R. equi to these antibiotics. The aim of the study was to determine the antimicrobial activity of 24 selected antibiotics against R. equi strains isolated from dead foals and from the environment of horse breeding farms with and without endemic R. equi infections. Minimum inhibitory concentration gradient strips were used to determine the lowest concentration of the antibiotic that inhibited the growth of R. equi. Based on normal MIC distribution, an epidemiologic cutoff values (ECOFF) were assessed for particular antibiotics and R. equi strains. The results were compared with ECOFFs for S. aureus, according to the European Committee on Antimicrobial Susceptibility Testing data. The data indicate that the lowest MIC values were obtained for clarithromycin, rifampicin, imipenem, and vancomycin. The majority of R. equi strains can be classified as wild type in relation to the majority of antibiotics. A small percentage of strains presented non-WT (NWT) with the exception of SXT, for which 35% of strains were classified as NWT. The lack of interpretative criteria for R. equi creates a real problem in the assessment of antibiotic sensitivity both for clinical and scientific purposes.

The novel and transferable erm(51) gene confers macrolides, lincosamides and streptogramins B (MLSB ) resistance to clonal Rhodococcus equi in the environment.

The use of mass antimicrobial treatment has been linked to the emergence of antimicrobial resistance in human and animal pathogens. Using whole-genome single-molecule real-time (SMRT) sequencing, we characterized genomic variability of multidrug-resistant Rhodococcus equi isolated from soil samples from 100 farms endemic for R. equi infections in Kentucky. We discovered the novel erm(51)-encoding resistance to MLSB in R. equi isolates from soil of horse-breeding farms. Erm(51) is inserted in a transposon (TnErm51) that is associated with a putative conjugative plasmid (pRErm51), a mobilizable plasmid (pMobErm51), or both enabling horizontal gene transfer to susceptible organisms and conferring high levels of resistance against MLSB in vitro. This new resistant genotype also carries a previously unidentified rpoB mutation conferring resistance to rifampicin. Isolates carrying both vapA and erm(51) were rarely found, indicating either a recent acquisition of erm(51) and/or impaired survival when isolates carry both genes. Isolates carrying erm(51) are closely related genetically and were likely selected by antimicrobial exposure in the environment.

ЭПИЗООТИЧЕСКАЯ СИТУАЦИЯ ПО ГЕЛЬМИНТОЗАМ ЛОШАДЕЙ В ЧАСТНЫХ ХОЗЯЙСТВАХ ЛЕНИНГРАДСКОЙ ОБЛАСТИ

To study the spread of helminth infections and diagnosis of the helminth fauna in pri-vate horse breeding farms of the Leningrad Region, feces were survey studied from foals for a year, animals aged 1 year to 3 years, 3 years to 6 years old, 6 to 10 years old and over 10 years old. Gastrointestinal nematodoses were diagnosed using Dar-ling`s method with advanced flotation fluid, culturing larvae by the method of Petrov&amp; Gagarin, and using microscopy of contents from perianal area.The dominance of gastro-intestinal strongylides in horses of all age groups has been found. Yearlings are infest-ed with trichonemas by 94.1%.Aling with age increasing, the intensity of invasion (II) is slightly reduced. In horses older than 10 years, the prevalence rate of trichonemic infection is 63.9%. Strongyloidosis was de-tected in 70.5% of foals up to a year old.At the age of one to 3 years, a slight decline in II is observed, but when reaching 3 years and further, with increasing age, II gradually increases. Horses from 3 to 6 years of age (II = 80.0%) are more infected with parascaris-es. Yearlings are infested with parascarises by 56.2%, and in horses older than 10 years, II is 30.7%.Horses are less infested with ox-yurises compared to other nematodes.The lowest levels of II by oxyurosis (23.5%) were found in yearlings, and most of all ani-mals were invaded at the age of 6 to 10 years (II = 50.0%).It should be noted that helminth fauna is formed by nematodes, which are geohelminths in the terms of their develop-mental biology.Perhaps there is a correlation between the invasion of horses of all age groups and the characteristics of keeping animals in small private farms.

ПЕРСПЕКТИВЫ РАЗВИТИЯ ЭКСПОРТА ПРОДУКЦИИ ПЛЕМЕННОГО КОНЕВОДСТВА РОССИЙСКОЙ ФЕДЕРАЦИИ

Authores analyzed the trade foreign balance of the Russian horse industry in the years 2016-2018, estimated the prospects for local and foreign markets of the products of Russian studs and horse breeding farms and gave recommendations for the sports horse breeding.

Análise econômico-financeira de sistemas de alimentação para equinos

Objetivou-se avaliar a viabilidade econômico-financeira de sistemas de alimentação para equinos utilizando capim-elefante e silagem de milho, como suplementação alimentar. Os indicadores zootécnicos e econômicos para a caracterização dos sistemas de alimentação foram obtidos juntos a um haras de criação de cavalos da raça Mangalarga Marchador. Projetou-se um horizonte para exploração da atividade de 12 anos e, a partir do uso de planilhas eletrônicas, foram projetados os fluxos de caixa a fim de verificar a viabilidade econômico-financeira. Utilizaram-se os indicadores econômicos de rentabilidade: valor presente líquido e taxa interna de retorno, bem como foram realizadas as análises de sensibilidade e risco em cada sistema de alimentação. Os sistemas foram viáveis financeiramente, por apresentarem um valor presente líquido positivo a uma taxa de desconto de 10% ao ano. A taxa interna de retorno foi de 11,11% para o sistema de alimentação que adotou o fornecimento de capim-elefante, ao passo que para o sistema de alimentação que utilizou silagem de milho, a rentabilidade obtida foi de 11,46%. O preço compra e venda de animais, em especial, de doadoras, foram os itens de maior influência sobre os resultados obtidos para o valor presente líquido. O risco econômico-financeiro para investimento nos sistemas de alimentação foi classificado como baixo.

Prevalence and risk factors associated with emergence of Rhodococcus equi resistance to macrolides and rifampicin in horse-breeding farms in Kentucky, USA

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 < 0.05). Seventy-six percent (76%) of farms yielded resistant R. equi, and resistance to macrolides and rifampicin was associated with their use at farms. The present study is the first to report the prevalence and distribution of resistant isolates in the environment of farms in Kentucky, USA. Collectively, previous reports and the data presented herein provide irrefutable evidence of emerging antimicrobial resistance in R. equi with alarming prevalence. Widespread dissemination and maintenance of resistance genes in the environment where many other pathogenic bacteria exist is a concern for both animal and human health.

Transfusion With 2 L of Hyperimmune Plasma is Superior to Transfusion of 1 L or Less for Protecting Foals Against Subclinical Pneumonia Attributed to Rhodococcus equi

Transfusing foals with Rhodococcus equi hyperimmune plasma (REHIP) is a standard practice at many horse-breeding farms to help prevent R. equi pneumonia. At many large breeding farms, pneumonia is most commonly recognized as subclinical based on thoracic ultrasonography findings. The efficacy of REHIP transfusion and the impact of the volume of plasma transfused for reducing the cumulative incidence of subclinical R. equi pneumonia are unknown. A retrospective cohort study was conducted among foals born and residing through weaning at a large breeding farm. Foals were transfused with either 0 L (n = 2 foals), 1 L (n = 85 foals), or 2 L (n = 62 foals) of REHIP within 36 hours of birth. Volume transfused was principally based on intended use of the foals. All foals at the ranch were routinely screened using thoracic ultrasonography at 5, 7, and 9 weeks of age to detect subclinical pneumonia attributed to R. equi based on farm history. The proportion of the foals receiving < 1 L REHIP that developed subclinical pneumonia (32%; 26/82) was significantly (P = .0068; chi-squared test) greater than that among foals transfused with 2 L of REHIP (12%; 8/68). Despite the important limitations of this observational study, it provides evidence supporting the need for well-designed clinical trials to evaluate the impact of the use and dose of REHIP for preventing subclinical pneumonia. Reducing the incidence of subclinical pneumonia is important because reducing antibiotic treatment of subclinical cases will decrease selection pressure for antimicrobial resistance in R. equi.

Identification of macrolide- and rifampicin-resistant Rhodococcus equi in environmental samples from equine breeding farms in central Kentucky during 2018

Rhodococcus equi causes severe pneumonia in foals and is most often recognized in people as an opportunistic pathogen. Longitudinal studies examining antimicrobial-resistant R. equi from environmental samples are lacking. We hypothesized that antimicrobial-resistant R. equi would be detectable in the ground (pasture soil or stall bedding) and air at breeding farms with previous documentation of foals infected with resistant isolates, and that concentrations of resistant isolates would increase over time during the foaling season. In this prospective cohort study, ground and air samples were collected from stalls and paddocks in January, March, May and July of 2018 at 10 horse-breeding farms with history of foal pneumonia attributed to macrolide- or Rifampicin-resistant R. equi. Environmental samples were cultured in the presence and absence of macrolides and Rifampicin to select for resistant organisms. Data were analyzed with linear mixed-effects and Hurdle models. Concentrations of total R. equi in bedding or air of stalls were significantly (P < 0.05) higher in January than other months. The proportion of resistant R. equi in soil samples from paddocks was significantly (P < 0.05) higher than stall bedding during all months. For each month, air samples from paddocks had a significantly (P < 0.05) higher proportion of resistant isolates than those from stalls. Fifty-five percent of resistant soil isolates and 34% of resistant air isolates were considered virulent by identification of the vapA gene. Concentrations of resistant R. equi isolates did not increase over time during the foaling season. Antimicrobial-resistant R. equi can persist in the environment at farms with a history of pneumonia caused by resistant R. equi infections, and exposure to resistant isolates in paddocks and stalls appears stable during the foaling season. Resistant isolates in the environment not only pose a risk for disease but also can serve as a repository for dissemination of resistance genes.

Current Situation and Trend about the Management of Horse-breeding Farms in the Hidaka Region in Hokkaido

Current Situation and Trend about the Management of Horse-breeding Farms in the Hidaka Region in Hokkaido

Foal-Level Risk Factors Associated With Development of Rhodococcus equi Pneumonia at a Quarter Horse Breeding Farm

The occurrence of Rhodococcus equi at farms varies, with disease occurring endemically at some farms, but only sporadically, or not at all at other farms. Only some foals residing on endemic farms develop clinical signs of disease. Limited evidence is available regarding foal-level risk factors for the development of R. equi pneumonia. The purpose of this study was to identify foal-level risk factors associated with the development of R. equi pneumonia among foals at a large breeding farm in Texas with a recurrent problem of R. equi pneumonia. A retrospective cohort study was conducted using data from foals born at the farm from January 2009 through December 2011 that met the criteria for inclusion. Dam-level, foal-level, and health-related data were collected from all foals. Independent variables were analyzed with logistic regression, controlling for the effect of year. Data from 787 foals born at the farm were included, of which 209 (27%) developed R. equi pneumonia. The cumulative incidence of disease at the farm varied significantly by year. Foals that were diagnosed with a prior morbidity besides R. equi were less likely to develop R. equi pneumonia.