Congenital Ocular Malformations

In the literature

Saraiva IQ, Delgado E. Congenital ocular malformations in dogs and cats: 123 cases. Vet Ophthalmol. 2020;23(6):964-978.

The Research …

Congenital ocular malformations are rare in dogs and cats and include abnormalities present at birth, after the eye opens, or at ≈6 to 8 weeks of age. These malformations result from abnormal embryonic development, which may occur spontaneously or due to gestational teratogens, including both genetic and nongenetic factors. Some congenital ocular disorders have been identified as heritable within a breed (eg, collie eye anomaly) and form the basis for breeding recommendations by veterinary ophthalmologists. In humans, congenital ocular malformations are a leading cause of childhood blindness, and veterinary models are often used to investigate disease mechanisms and treatment options. 

This study sought to identify the prevalence and epidemiology of congenital ocular malformations in dogs and cats presented to a veterinary teaching hospital in Portugal. A prospective and retrospective evaluation of medical records included data on age, breed, sex, medical history, reason for presentation, clinical findings, vision impairment, and treatment options.

Of the 32,974 dogs and 13,977 cats evaluated, 103 (0.3%) dogs and 20 (0.1%) cats were diagnosed with a congenital malformation in one or both eyes. The most commonly identified ocular malformations in both dogs and cats were congenital cataracts, microphthalmia, and persistent pupillary membranes. Among dogs with ocular dermoids, French bulldogs were significantly overrepresented (75% of cases). No sex predisposition was identified for any congenital ocular malformation. 

Surgery was performed on 25 dogs to address congenital ocular malformations. The most common procedures were ocular dermoid removal (12 dogs) and cataract phacoemulsification with intraocular lens implantation (9 dogs). Four cats underwent surgery (3 for microphthalmos and/or entropion and 1 for enucleation due to congenital glaucoma).  

This study highlighted the rarity of congenital ocular malformations in dogs and cats and provided insight into these conditions. It is important to be aware of the most common congenital eye conditions, as treatment options may be available. Additional exploration of the possible hereditary nature of ocular dermoids in French bulldogs is warranted.

… The Takeaways

Key pearls to put into practice:

• Congenital ocular malformations are rare in dogs and cats. The most frequently diagnosed conditions are congenital cataracts, microphthalmia, and persistent pupillary membranes. Congenital cataracts and microphthalmia may affect vision, and referral to a veterinary ophthalmologist for surgical evaluation is recommended.

• Persistent pupillary membranes vary in appearance and are named based on the structures with which they associate (ie, iris-to-iris, iris-to-lens, iris-to-cornea). In addition, persistent pupillary membranes may simply appear as a cluster of pigment on the anterior lens capsule without overt pigment strands; this type of persistent pupillary membrane is common in dogs, especially cocker spaniels. The most common type of persistent pupillary membrane in cats is iris-to-cornea, and a corneal opacity is usually present at the endothelial attachment point.

• French bulldogs appear to be predisposed to ocular dermoids. Clinically, dermoids are typically located on the eyelids, conjunctiva, or limbus of the cornea. The most common complication is corneal irritation, and surgery to remove the dermoid is often recommended.