Dr. Barchas,

I have a Pug whose eyes are always filled with mucus. What is the cause, and how can I fix this?

Dawn, Jacksonville, FL

Several breeds of dogs and cats are predisposed to excessive discharge from their eyes. The breeds include Pugs, Pekinese, Shih Tzus, Persians, Himalayans, Chihuahuas, and Boston Terriers, among others. These animals have shallow eye sockets, which cause the eyes to protrude (or bulge) prominently from the face.

In some cases, the discharge is harmless. The irregular shape of the eye socket in the above breeds interferes with the normal drainage of tears. Mucus is a component of tears, and it can build up. In fact, even pets (and people) with normal eye sockets occasionally develop a small amount of mucus in the central corners of the eyes, especially after sleeping.

However, if you consistently notice mucus or excessive discharge from your pet’s eyes, a more serious problem is possible. Pets with prominent or bulging eyes can have trouble closing their eyelids completely. This can lead to irritation, pain, and eye damage. In any pet, excessive discharge from the eye can be a sign of an eye infection, eye trauma, glaucoma, ulcers on the surface of the eye, or a syndrome in which the eye does not produce tears appropriately.

Therefore, although the mucus may be normal in your Pug’s case, I recommend a trip to your vet to make sure there’s nothing to worry about.