Eye disorders can occur because of diseases affecting other parts of the body. They can occur with inherited, infectious, degenerative, and cancerous disorders. Often, discovering a change in the eyes can help uncover the systemic disorder sooner than if the eyes had not been examined. Diseases affecting the blood vessels or nervous system are likely to produce changes in the eyes. If your horse has a disease that affects both eyes, your veterinarian will often look for diseases in the rest of the body.
In horses, generalized infectious diseases (such as adenovirus, equine influenza, strangles, Rhodococcus equi, leptospirosis, Lyme disease, and salmonellosis) can cause inflammation of the conjunctiva (conjunctivitis) or uvea (uveitis). Parasite infections (for example, onchocerciasis or habronemiasis) can also occur in or around the eyes.
Also see professional content regarding eye disorders resulting from generalized disease in animals.