In rabbits, a number of things can cause runny eyes. Nasolacrimal duct obstruction is one of the most common causes of discharge. This duct runs from the inner eye to the nose, and normally the natural eye lubricating tears drain down this. The duct’s opening into the nasal area is very small, which makes it prone to blockage. If this is blocked obviously the tears cannot drain as usual.

The most usual treatment is to flush the ducts but a significant number of rabbits need long-term treatment. Some rabbits like this need repeated flushing, whereas others need life-long systemic (whole body) antibiotic treatment.

In nearly all other causes of runny eyes in rabbits that I am aware of, there are other obvious symptoms that affect the eyes or appetite.