Corneal Dermoid

A considerable number of corneal conditions have been identified in the dog. Congenital conditions include corneal dermoid which is reasonably common. Dermoids are superficial masses present from birth which contain many of the elements of normal hairy skin. They usually involve the cornea and conjunctiva, nictitating membrane (membrane involved in winking of the eyelids) and, less commonly, the eyelids. Dermoids are fairly common in the dog and usually affect one eye. Technically, corneal dermoid is classified as a type of choristoma. A choristoma is a developmental defect in which groups of cells of one organ are located in a nearby organ where they don't belong.

Corneal dermoid is a congenital tumor on the surface of the eye observed in newborn animals, and may involve one or both eyes. The affected cornea appears to be covered over part of its surface with white, sometimes haired and usually pigmented skin. Hair follicles, sebaceous glands, and cysts lined with epithelium and filled with keratin (the main component of the tissues such as hair and nails), sweat glands are common. The corneal connective tissue may be thickened and lined with blood vessels but is otherwise unaffected. Cysts may also affect the cornea; they resemble the lesions seen on the skin.

Breeds Affected by Corneal Dermoid

This condition is known to occur in large breed dogs such as St. Bernards, German Shepherds, short-legged dogs such as Basset Hounds, Dachshunds and Welsh Corgis and cats.

Some puppies may have chronic epiphora and eye discharge. Surgical removal of dermoids (superficial keratectomy) is usually performed when the puppy is old enough for routine general anesthesia. Surgery may lead to complete remission of signs and minimal scarring of the cornea. Although hair may be removed by manual epilation or electroepilation, it may regrow. If the dermoid has is not totally removed. some degree of recurrence can be expected.

References:
1. Veterinary Pathology. Thomas Carlyle Jones, Ronald Duncan Hunt, Norville W. King
2. Notes on Veterinary Ophthalmology. Sheila M. Crispin
3. Surgical correction of corneal dermoid in a dog. Lee JI, Kim MJ, Kim IH, Kim YB, Kim MC.

Canine Eye Diseases and Vision Disorders