The Bullmastiff is a very large and strong dog, but like all dogs is prone to some health issues - specifically eye disorders. Although this does not mean all Bullmastiffs will develop these eye disorders, they are more prone to them than other breeds of dog.

The two eye disorders that most often affect the Bullmastiff are Ectropion and Entropion. Ectropion is a defect in the conformation of the eye. The eyelids will sag or have a rolling out appearance, which results in too much of the eye being exposed, causing irritation to the eye. Ectropion is inherited by mean of polygenic inheritance. Polygenic inheritance is something inherited by a number for factors such as gender, breed, nutrition, rate of growth, etc. rather than by just one gene.

Ectropion comes from the genes that determine the make up of the structure of the eyelids as well as the skin on the head, face, and all areas surrounding the eyes. The dogs most affected by Ectropion are dogs with exaggerated facial features characteristic of that specific breed - dogs like boxers, Basset hounds, Great Danes, Saint Bernards, mastiffs, and bullmastiffs. Some of the giant breeds like Great Danes, Saint Bernards, and mastiffs have an ectropic lower lid and entropic corner lids.

Dogs that have Ectropion are more likely to develop allergies and bacterial conjunctivitis, which is an inflammation of the membrane that covers the periphery of the eye surface and eyelid liner. This is because so much of their eyes are exposed. Ectropion is usually diagnosed because they have a discharge in their eyes, decreased amount of tear production, and reddened conjunctiva, all of which can be very painful to the dog.

Treatment can vary depending on the severity of the Ectropion, ranging from mild requiring no treatment to severe Ectropion, which will require surgery to remove a small amount of tissue from the eyelid.

Entropion is a medical condition affecting dogs where the eyelid folds inward. It causes the eyelashes to rub against the cornea constantly causing the dog a lot of pain. Symptoms of Entropion are pain and redness around the eye, puffiness around the eye, sagging skin around the eye, excessive tearing, sensitivity to light and wind, and decreased vision. Treatment for this disorder is a surgical procedure where the excess skin on the outside lids is removed. It is important to have this surgery performed early enough before the cornea is permanently damaged.

Progressive retinal atrophy (PRA) is another genetic disease that affects certain breeds of dog, the bullmastiff being one of them. One of the characteristics of PRA is the gradual bilateral degeneration of the retina, eventually leading to vision loss and then blindness. There are specific tests to determine if your dog is suffering from PRA. Unfortunately, there is no treatment for this disease.