Detection of Chlamydophila caviae and Streptococcus equi subsp. zooepidemicus in horses with signs of rhinitis and conjunctivitis.

The study investigates the joint presence of Chlamydophila caviae and Streptococcus equi subsp. zooepidemicus pathogens in horses showing symptoms of conjunctivitis and rhinitis, proposing a synergistic effect in disease progression.

Overview of the Study

• The study was conducted at a Trakehner horse stud farm where all the 33 foals from a particular birth cohort developed signs of rhinosinusitis and conjunctivitis. Moreover, 7 older horses showed recurring signs of conjunctivitis.
• The research involved examination of nasal and eye swabs from the affected horses, which were analysed using several techniques such as bacterial and cell culture, real-time PCR, ArrayTube microarray analysis, and DNA sequencing.

Findings and Interpretations

• The analysis led to the identification of two pathogens, Chlamydophila (C.) caviae—reported for the first time in horses—and Streptococcus (S.) equi subsp. zooepidemicus.
• Researchers hypothesised a possibility of a synergistic action between these two agents where the primary lesions were possibly caused by C. caviae and then exacerbated by S. equi subsp. zooepidemicus.
• This assumption builds upon certain indications: the conjunctivitis caused by a mono-infection with C. caviae, recurring clinical symptoms in the affected animals, and the ineffectiveness of the administered antibiotic therapy including trimethoprim-sulfonamide, enrofloxacin, and amoxicillin.

Significance and Further Questions

• The discovery of C. caviae in horses provokes further questions concerning its significance and its natural host range.
• This result may suggest that the range of hosts for this agent might be broader than previously thought, which would have implications for how equine disorders are diagnosed and treated.
• The interaction between the identified pathogens and their role in disease progression also warrants further investigation, which can provide new insights into managing and treating such co-infections.