Mycoplasmas associated with bovine conjunctivitis and keratoconjunctivitis

Area of Science:

• Veterinary Medicine
• Bovine Pathology
• Microbiology

Background:

• Outbreaks of ocular disease in fattening calves presented with lacrimation, resembling infectious bovine keratoconjunctivitis.
• Clinical signs progressed to include bronchopneumonia within days of initial ocular symptoms.

Purpose of the Study:

• To identify the causative agents of a sudden-onset ocular and respiratory disease outbreak in two herds of fattening calves.
• To investigate the role of Mycoplasma species and infectious bovine rhinotracheitis (IBR) virus in the observed pathology.

Main Methods:

• Collection of conjunctival swabs from affected calves for microbiological and viral isolation.
• Necropsy and lung tissue sampling from deceased calves for Mycoplasma identification.
• Ocular swab collection from unaffected bulls for comparative analysis.

Main Results:

• Mycoplasma (M.) bovigenitalium, M. bovirhinis, and infectious bovine rhinotracheitis (IBR) virus were isolated from conjunctival swabs.
• M. bovigenitalium was also detected in the pneumonic lungs of dead calves in one herd.
• Moraxella bovis, a common cause of infectious bovine keratoconjunctivitis, was not isolated.
• M. bovoculi was isolated from a chronically affected cow housed with the calves.

Conclusions:

• Mycoplasma bovigenitalium and IBR virus are implicated in the observed outbreak of keratoconjunctivitis and subsequent bronchopneumonia in calves.
• The findings suggest a multifactorial etiology, potentially involving Mycoplasma species beyond M. bovoculi.
• Further research is warranted to elucidate the pathogenesis and transmission dynamics of these agents in bovine respiratory and ocular diseases.