Clinical signs of brachycephalic ocular syndrome in 93 dogs.

Background: Brachycephalic breeds have anatomical skull changes that are responsible for ocular clinical signs, known as the brachycephalic ocular syndrome (BOS). Their popularity has increased in recent years but the excessive pressure of selection lead to extreme conformation of skull shapes, resulting in facial alterations that can put these dogs' vision at risk.

Objectives: This study aimed to analyse the ocular disorders in a sample of 93 brachycephalic dogs to better characterize the disease complex BOS.

Material and methods: Brachycephalic dogs were submitted to a complete ophthalmological examination. The studied parameters included animal's sex, age and breed, age, ophthalmological tests performed, results of complementary exams, clinical signs, ocular disorders, treatment protocols and their outcomes. Data were organized using Microsoft Office Excel 2007® and statistical analysis was performed with IBM SPSS Statistics 20®.

Results: The studied population included 93 brachycephalic dogs 45 males (48%) and 48 females (52%) from different breeds: French Bulldog (n = 38), Shih-Tzu (n = 22), Pug (n = 17), English Bulldog (n = 5), Pekingese (n = 4), Boxer (n = 4) and Boston Terrier (n = 3), aged between 0.2-16 years, median 4.65 years. The most frequent ocular abnormalities were corneal ulcers in 44%, corneal pigmentation in 36%, corneal fibrosis in 25% and entropion in 22% of the animals. There was a higher incidence of corneal pigmentary keratitis in Pugs (53%) and corneal fibrosis in Shih Tzus (36%). The most common surgical techniques were medial canthoplasty in 22%, conjunctival flap in 10% and electroepilation in 7% of the cases, without post-operative complications.

Conclusions: This study contributed to a better characterization of the disease complex brachycephalic ocular syndrome. The percentage of ocular disorders like entropion, corneal pigmentation, fibrosis and ulcers was high, highlighting the importance of a regular ophthalmological check-up, and early diagnosis of the primary disorders. A higher incidence of corneal pigmentation was noticed in Pugs and corneal fibrosis in Shih Tzus, which suggests that some brachycephalic breeds may be predisposed to certain ocular abnormalities. A responsible reproductive strategy should be implemented to avoid undesired transmission of the abnormal traits to the offspring.