Infectious bovine keratoconjunctivitis I. Experimental production

Area of Science:

• Ophthalmology
• Veterinary Medicine
• Microbiology

Background:

• Bovine keratoconjunctivitis is a significant ocular disease in cattle.
• Multiple microorganisms, including Moraxella bovis and infectious bovine rhinotracheitis virus, are implicated in its pathogenesis.
• Understanding the specific roles of these pathogens and host responses is crucial for effective disease management.

Purpose of the Study:

• To investigate the pathogenicity of various microorganisms in inducing bovine keratoconjunctivitis.
• To determine the effects of different inoculation routes and ultraviolet irradiation on disease development.
• To assess the development of resistance following M. bovis infection.

Main Methods:

• Twenty calves were inoculated with combinations of Moraxella bovis, infectious bovine rhinotracheitis virus, bovine adenovirus, bovine parainfluenza-3 virus, and Mycoplasma bovoculi.
• Inoculations were performed via conjunctival instillation or direct inoculation of the conjunctiva or cornea.
• Calf eyes were exposed to natural or artificial ultraviolet irradiation; disease development and microbial establishment were monitored.

Main Results:

• Bovine adenovirus and parainfluenza-3 virus did not establish in the eye or cause keratoconjunctivitis.
• Moraxella bovis and infectious bovine rhinotracheitis virus established and caused disease.
• Intracorneal inoculation of M. bovis and Mycoplasma bovoculi resulted in severe keratoconjunctivitis; prior M. bovis infection conferred resistance to subsequent exposures.

Conclusions:

• Moraxella bovis and infectious bovine rhinotracheitis virus are key pathogens in bovine keratoconjunctivitis.
• Intracorneal inoculation is an effective method for inducing severe disease, particularly with M. bovis and Mycoplasma bovoculi.
• Acquired resistance following M. bovis infection suggests potential for developing preventative strategies.