“Normal” eyelid conformation for dogs is taken to be an almond shaped palpebral fissure (eyelid opening) with the lids resting on the globe and a small amount of scleral show (white area outside the cornea) on the outside corner but none nasally.
The breed standards for many breeds unfortunately call for eyelid conformation that deviates from this ideal. This is important as the eyelid conformation affects eyelid function: to cover and protect the eyes and vitally, to spread the tear film. This means that many breeds are predisposed to eye disease are due to poor eyelid design.
Brachycephalic breeds
Brachycephalic breeds have reduced orbital space due to the flattening of their facial features. This makes for prominent eyeballs, often poorly covered by the eyelids with excessive scleral show all around. This places these breeds at risk of globe proptosis and also of risk of corneal ulcers and corneral exposure issues due to drying of the central cornea. These breeds often have a prominent nasal skin folds that can have hairs directly touching the cornea causing irritation and also the skin fold pushing the lower lid creating an entropion. At Animal Eye Care we see many dogs with serious corneal disease, up to corneal rupture, resulting from these prominent globes, and medial entropion (the inside eyelid cornea rolling in).
Causes
Breeds with large amounts of loose skin around the face often have poor supporting ligament structure around the eyes and large palpebral fissures, often manifest as a diamond shaped eyelid. This is commonly seen in the large/giant breed dogs. This allows the eyelids to collapse and fall away from the eye (ectropion) with a sequel of chronic conjunctivitis or fall in towards the eye (entropion) with corneal irritation and ulceration. In severe cases of diamond eye you can get both entropion and ectropion in the same lid.
We appreciate that some of these facial features are intrinsic to the appearance of the breed. “Good” examples of the breeds rarely require intervention however there are many individual dogs bred with extreme facial conformation causing considerable distress and expense. Some of these issues occur later in life as the skin starts with an aging “sag”. Eyelid conformation and eye health is an important component of the new veterinary checks introduced in the UK at shows before progression to the Group championships.
Breeding to improve ocular health
Breeding to improve ocular health by breeding away from extreme examples will reflect the concern that the general public have with pedigree dog breeding and will hopefully dramatically reduce the incidence of dogs requiring surgical intervention to maintain their comfort. Lid conformation is not specifically mentioned in the ACES certificate as the mode of inheritance is not proven although it is certainly breed/ line related. A “clear” ACES certificate does therefore not mean that the conformation of the eyes and face can be ignored when making breeding choices. At Animal Eye Care we are keen to improve dog health by encouraging breeding for good eyelid conformation. We will be pleased to see fewer dogs with corneal ulcers and corneal scar tissue from such problems.
