Infectious keratoconjunctivitis in free-ranging mule deer (Odocoileus hemionus) from Zion National Park, Utah

Area of Science:

• Veterinary Ophthalmology
• Wildlife Disease Ecology
• Microbiology

Background:

• Infectious keratoconjunctivitis (IK) is a common ocular disease affecting various animal species.
• Understanding IK outbreaks in wildlife populations is crucial for conservation and disease management.
• Mule deer (Odocoileus hemionus) are susceptible to ocular infections, impacting herd health.

Purpose of the Study:

• To investigate an epizootic of infectious keratoconjunctivitis in free-ranging mule deer.
• To identify causative agents and assess clinical signs and disease progression.
• To document the recovery of affected deer and identify potential persistent infections.

Main Methods:

• Opportunistic field study of a mule deer population in Zion National Park, Utah.
• Sample collection from conjunctiva for isolation of bacterial and parasitic agents.
• Clinical observations of affected deer, noting signs like corneal opacity, blepharospasm, and epiphora.
• Longitudinal monitoring to document disease recovery and potential persistence.

Main Results:

• Moraxella sp. and Chlamydia sp. were isolated from two of seven deer.
• Thelazia californiensis was found on the conjunctivas of six of seven deer.
• Adult deer exhibited a higher clinical incidence than juveniles; corneal opacity was prominent in 1992-1993, while blepharospasm and epiphora were more frequent in 1993-1994.
• Clinical recovery was documented in three deer, and Moraxella sp. was recovered from a clinically unaffected deer one year post-epizootic.

Conclusions:

• The study identified Moraxella sp., Chlamydia sp., and Thelazia californiensis as associated with the IK epizootic in mule deer.
• Age-related differences in clinical presentation and disease progression were observed.
• The potential for persistent Moraxella sp. infection in clinically unaffected deer warrants further investigation.