Red eyes in Boston terriers are often signs of dry eyes or corneal ulcers. According to Boston Terrier Rescue of North Texas, dry eyes, or keratoconjunctivitis sicca, are common in the breed. This condition is characterized by a lack of tear production. The rescue site reports that dry eyes have several possible causes, including infection, hypothyroidism and diseases of the immune system.
Boston Terrier Rescue of North Texas reports that terriers with keratoconjunctivitis sicca have a mucus discharge from their eyes in addition to the red coloring. A dog with these symptoms should be seen by a veterinarian and, if dry eyes are diagnosed, treatment should begin, typically involving prescription of an ointment and artificial tears.
According to Mercola, flat-faced dogs such as Boston terriers are also prone to corneal ulcers, which are injuries to the outer layer of the eye. Mercola lists numerous causes, including but not limited to, scratches, punctures, chemical burns, foreign objects in the eyes, lack of tear production and infections. In addition to redness, other symptoms are often present, such as excessive tearing, pawing at the eye and squinting. A dog with these symptoms should be seen by a vet. Treatment options, such as medication or surgery, are determined by the cause and seriousness of the injury.