The cornea is the clear, shiny membrane, which makes up the surface of the eyeball. The cornea is made of 3 layers: The epithelium, the stroma, and the deepest layer is Descemet's membrane. When these layers wear down, this is called a corneal ulcer or a corneal abrasion.
A corneal ulcer is erosion through the whole epithelium and into the stroma. If the erosion goes through the epithelium and stroma to the level of Descemet's membrane (the very deepest layer), it is termed: descemetocele. If Descemet's membrane ruptures, the liquid that is normally inside of the eyeball leaks out and the eye actually collapses.
There are several causes for corneal ulcers in dogs. The most common is trauma. An ulcer may result from an injury, for example if a Pug dog rubs his eye too harshly on something or a foreign object scratches the eye.
The second most common cause is chemical burn of the dog's cornea. This may happen when irritating shampoo gets into the Pug’s eye. For this reason, it is strongly suggested to only use a gentle canine shampoo (never use human shampoo) and to be as careful as possible that any shampoo or conditioner does not enter into the Pug dog's eyes while you are bathing him.
Other, rarer, reasons are bacterial infections, viral infections, and other diseases. These may begin in the dog’s eye or develop elsewhere and then affect the eye.
Some diseases that may have a link to this include Keratoconjunctivitis Sicca (a drying of the cornea that happens when there is an abnormal tear formation), and diseases of the endocrine system (diabetes mellitus, hyperadrenocorticism, and hypothyroidism).
- A corneal ulcer can cause a Pug to be in a lot of pain. In reaction to pain, most dogs rub the affected eye with their paw or will try to rub it against surfaces, just as their blanket or the carpeting in an effort to find relief.
- A dog may try to protect his eye, by keeping his eyes closed.
- In some cases, there will be a discharge that puddles in the corner of the dog’s eye. It may stay there for a while and then eventually run down the dog’ face.
- To protect the eye, they keep the lids tightly closed. Occasionally, there will be a discharge that collects in the corner of the eye or runs down the face.