The third eyelid is situated between the cornea and the eyelids at the inside corner of the eye. In dogs it contains tear glands responsible for the lubrication and protection of the eye. This gland secretes 40–60 % of the dog’s tears. It is kept in position by a thin fibrous band which, if weakened or absent, may result in the gland prolapsing. The exposed gland can be damaged by drying out and secondary inflammation or infection. This can destroy the glandular tissue and thus result in a dry eye. This is a common problem in Bulldogs, Spaniels, Shar Pei, Chow Chow and Daschunds, but is seen in all breeds.
The enlarged gland is seen in the inner corner of the eye and is usually red, hence the name “cherry eye”. In longstanding cases the gland may become pigmented.
Because the gland secretes a substantial amount of the dog’s tears it is very important that it is not removed, but replaced, as soon as possible, before damage to the glandular tissue occurs.
The correct treatment is to salvage this gland and replace it in a small conjunctival sac. This procedure requires good magnification using an operating microscope and very fine dissolvable surgical suture material. Although the surgical procedure is very successful, re-prolapse may occur and is well described in the literature. Such prolapse may occur in cases where the gland has been exposed for an extended time or when previous surgery has resulted in scar tissue formation.