Listeria keratitis in a horse.

The research article reports a rare case of keratitis, an inflammation of the cornea, in a mare caused by the bacterium, Listeria monocytogenes. This is distinctive as there is no other reported case of keratitis associated with L. monocytogenes in horses.

Overview of the case

• The mare showed symptoms of epiphora, a condition characterized by an excess of tears, and signs of pain in the right eye, leading the veterinarians to suspect an ocular problem.
• The researchers took a sample from a lesion on the cornea from which they successfully isolated Listeria monocytogenes.
• The presence of the bacteria was further supported by cytologic examination, a diagnostic test that examines the cells under a microscope.
• These findings confirmed that the horse’s eye condition, keratitis, was attributable to L. monocytogenes infection.

Significance of Listeria monocytogenes

• Listeria monocytogenes is known to be commonly found in various environmental sources, but rarely identified as a cause of keratitis in animals.
• The bacterium is known to cause listeriosis, a dangerous infection, primarily in humans. Animals may also contract the infection, but this usually results in gastrointestinal problems rather than ocular ailments.
• This case therefore marks the first reported instance of L. monocytogenes causing keratitis in a horse, and expands our understanding of the diseases the bacterium can cause.

Implications of the study

• This first reported instance of keratitis in a horse associated with L. monocytogenes sheds light on the potential for this bacterium to cause not only gastrointestinal issues, but also rare ocular conditions in animals.
• The case suggests that veterinarians need to include L. monocytogenes as a possible cause when diagnosing keratitis in horses.
• Further research is needed to explore the prevalence and pathology of Listeria keratitis in equine medicine and to establish adequate treatment protocols.