Chlamydia psittaci infection as a cause of respiratory disease in neonatal foals.
Authors: Gough S L, Carrick J, Raidal S L, Keane S, Collins N, Cudmore L, Russell C M, Raidal S, Hughes K J
Journal: Equine veterinary journal
Summary
# Editorial Summary: *Chlamydia psittaci* Infection in Neonatal Foals Between 2016 and 2018, researchers across three Australian referral hospitals identified 15 critically ill neonatal foals presenting with acute respiratory distress caused by *Chlamydia psittaci*—a pathogen previously unrecognised as a cause of neonatal equine respiratory disease. The retrospective case series examined clinical presentation, clinicopathological findings, and post-mortem features across the cohort, utilising PCR testing on multiple sample types including nasal secretions, rectal mucosa, lung tissue and foetal membranes. Thirteen of the 15 foals (87%) died or were euthanised within 36 hours of hospitalisation; necropsy findings consistently revealed bronchopneumonia, pulmonary congestion, hepatic congestion and hepatic inflammation, with *C. psittaci* detected in lung tissue in 11 of 14 post-mortem cases examined. Clinicians should now include *C. psittaci* in their differential diagnosis for neonatal foals presenting with severe systemic disease or equine neonatal acute respiratory distress syndrome (EqNARDS), whilst practising strict biosecurity protocols including appropriate PPE, as this organism represents a zoonotic risk to handlers and veterinary staff. The high case fatality rate and acute presentation underscore the importance of rapid diagnostic testing in foals with unexplained acute respiratory deterioration within the first 24–48 hours of life.
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Practical Takeaways
- •C. psittaci should now be considered in the differential diagnosis for critically ill neonatal foals with severe respiratory disease, including those presenting with EqNARDS
- •Use appropriate personal protective equipment when handling foals with suspected or confirmed C. psittaci infection, as it is a zoonotic pathogen with occupational health implications
- •Diagnostic sampling should include nasal secretions, rectal swabs, and lung tissue (post-mortem) with PCR testing for optimal case detection
Key Findings
- •15 neonatal foals with C. psittaci infection presented with acute respiratory distress over 2016-2018, representing the first documented association between this pathogen and neonatal respiratory disease in foals
- •Mortality was high with 13 of 15 foals (87%) dying or euthanized within 36 hours of hospitalization
- •PCR detection was successful from lung tissue (11/14 foals at necropsy), rectal mucosa (5/7 live foals), and nasal secretions (4/6 live foals)
- •Post-mortem findings included bronchopneumonia, pulmonary congestion, hepatic congestion and inflammation