A retrospective study of surgical correction of 18 cases (16 dogs) of eversion of nictitating membrane

Everted third eyelid cartilage is a common ocular disease in young, large breed dogs. The inappropriate third eyelid margin position impairs optimal tear film distribution and drainage and may contribute to conjunctivitis and exposure keratopathy. This condition was presumed to be congenital in certain breeds of dogs. Possible unequal growth rates of the bulbar and palpebral cartilage surfaces and/or an unequal growth rate of the adherent conjunctiva were hypothesized as contributing factors [1,2]. Different techniques for restoration of the anatomical position of the everted nictating membrane have been reported. However, few clinical reports evaluated postoperative results and relapse rate. The purpose of this study is to describe and evaluate surgical treatment of third eyelid cartilage eversion in dogs, with or without concomitant nictitans gland prolapse. A retrospective analysis of cases of eversion of third eyelid cartilage in dogs, between January 2010 and December 2017 was performed. The sex, breed and age at the time of diagnosis were recorded. The presence of other concurrent ocular diseases and surgical treatment were also recorded. Follow-up information was obtained from medical records and subsequently by telephone conversation with the owner. Sixteen dogs representing 18 everted third eyelid cartilage were included in this study. The sex distribution included 9 intact males and 7 intact females. Six dogs were Neapolitan Mastiffs, three were English Bulldogs, two were Great Danes, two were Boxer, with one each of the following breeds: Dachshund, Cane Corso and Rhodesian Ridgeback. Ages ranged from 3 months to 8 months. Only two dogs were bilaterally affected. Surgical treatment provided the excision of 2 mm of the folded cartilage, through posterior conjunctival approach. The same approach was used to perform a Morgan Pocket technique, also in dogs without prolapse of the nictitans gland. Incisions were finally apposed by simple continuous suture with pds 5/0 until 1-2 mm of incision’s end. In one dog a double approach was performed: the excision of the folded cartilage through anterior conjunctival approach while the Pocket technique through posterior conjunctival approach, however, mild inflammation of the third eyelid was observed. All dogs had good results in terms of cartilage correction with no recurrence. In conclusion, the association of Morgan Pocket technique to the excision of folded cartilage may be considered in the dogs with everted cartilage, in order to prevent the prolapse of the gland and probably the relapse of the eversion. Bulbar approach to the scrolled portion of cartilage, in the dog has the advantage that dissection is easier with less adhesion of the cartilage to overlying conjunctiva. Although it was suggested [3] that corneal damage may occur from resulting scarring if approach through the bulbar aspect is chosen, the association of Pocket technique may be beneficial in reducing the possibility of traumatic corneal scarring in the postoperative period.