MRSA was present in a population of horses in Australia. Genotypic analysis of the isolates identified the MRSA strain as CC8 S. aureus. Further research needs to be undertaken to evaluate MRSA infection and colonisation of horses and personnel in Australia.

Reference values for 2-D and M-mode echocardiographic variables in clinically normal Thoroughbred foals up to 4 months of age and approximately 190 kg body weight may assist in the interpretation of echocardiograms of Thoroughbred foals of similar age and body weight with suspected congenital or acquired cardiac disease.

SummaryReason for performing study: The repeatability of various echocardiographic measurements is unknown. Objectives: To determine the intraoperator, intraobserver and interoperator variability of echocardiographic measures in healthy foals. Methods: Echocardiographic examinations were carried out on 6 healthy foals by 3 experienced echocardiographers. Intraoperator variability was determined by having a single echocardiographer obtain and measure images from 6 foals scanned on 3 consecutive days. Interoperator and intraobserver variability were determined by having 3 echocardiographers each obtain images from an additional 6 sedated foals. Within-day interoperator variability was determined by having each echocardiographer measure their own images. Intraobserver variability was determined by having a single echocardiographer measure images obtained by all 3 echocardiographers. The coefficient of variation (CV) and standard error were calculated for each measure. Results: The variability for most measurements was either very low (CV<5%) or low (CV = 5-15%). Measurements of right ventricular internal diameter (RVID) in systole and E-point to septal separation (EPSS) showed moderate (CV 15-25%) to high variability (CV>25%) in all 3 categories. Measurements of the left ventricular ejection time (LVET) and velocity time integral from the right parasternal long axis view of right outflow tract in the fourth intercostal space showed moderate intraoperator variability. Measurements of the LVET, RVID in diastole and left atrial appendage (LAA) showed moderate interoperator variability and measurements of the RVID in diastole and acceleration time from the short axis view of the right outflow tract in the right third intercostal space showed moderate interobserver variability. Conclusion:The intraoperator, intraobserver and interoperator variabilities for most echocardiographic measurements in foals are low. Potential relevance: Most standard transthoracic echocardiographic measurements in foals have a low enough variability to warrant their use in serial clinical evaluations or experimental studies. Repeated measurements of RVID, EPSS, LVET and LAA should be interpreted with caution.

Summary Background During 2016–2018, 15 critically ill neonatal foals with acute respiratory distress associated with Chlamydia psittaci infection were presented to three referral hospitals in New South Wales. Chlamydia psittaci has not previously been associated with the development of neonatal respiratory disease. Objectives To investigate and describe the clinical features and outcome of C. psittaci infection in neonatal foals. Study design Multicentre retrospective case series. Methods The clinical, clinicopathological, necropsy and histological features of 15 foals with confirmed C. psittaci infection were reviewed and reported. Results Thirteen foals with C. psittaci infection died or were subjected to euthanasia within 36 h of hospitalisation and two foals survived to discharge. Findings during post‐mortem examination of nonsurviving foals included bronchopneumonia, pulmonary congestion, hepatic congestion and hepatic inflammation. Detection of C. psittaci was achieved using polymerase chain reaction (PCR) testing of swabs of nasal secretions (4/6) and rectal mucosa (5/7) from live foals, lung tissues of foals at necropsy (11/14) and foetal membranes (4/5). Main limitations Small numbers of confirmed cases of neonatal C. psittaci infection and inconsistent sampling methods. Conclusions Chlamydia psittaci should be considered a differential diagnosis for neonatal foals with signs of severe systemic disease, including equine neonatal acute respiratory distress syndrome (EqNARDS). Chlamydia psittaci is a zoonotic pathogen and a personal protective equipment (PPE) should be worn for the management of foals with suspected or confirmed infection.

The prevalence of severe hyponatraemia in this study population was 4%. The majority of foals with severe hyponatraemia did not demonstrate direct clinical manifestations as a result of the low serum sodium concentration. The outcome of foals with severe hyponatraemia was mostly favourable.