Clinical signs of brachycephalic ocular syndrome in 93 dogs

Abstract

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.

Keywords: Brachycephalic ocular syndrome; brachycephalic breeds; Corneal fibrosis; Corneal ulcers; Medial entropion; corneal pigmentary keratitis.

Fig. 1

Female Pug with excessive nasal folds. Notice its proximity to the medial canthus

Fig. 2

A 2 years old male French Bulldog with a right eye corneal ulcer affecting the mid stroma, accompanied by corneal oedema, neovascularization and granulation tissue

Fig. 3

A male Pug with bilateral medial corneal pigmentation. In the right we can see an image of the left eye, showing the superficial pigmentary keratitis affecting the upper and lower medial quadrants of the cornea, and already impairing vision

Fig. 4

A one-year-old male French Bulldog after surgical correction of the Brachycephalic Ocular Syndrome. A bilateral medial cantoplasty was performed to shorten the eyelid fissure, correcting the lagophthalmia, addressing caruncular trichiasis and correcting the bilateral medial entropion, preserving the lacrimal puncta to avoid epiphora in the future

Fig. 5

A six-year-old female Pug before and after MCP and resection of the excessive nasal fold. Note that bilateral medial cantoplasty was performed to shorten the eyelid fissure, correcting the lagophthalmia, addressing caruncular trichiasis and correcting the bilateral medial entropion, preserving the lacrimal puncta to avoid epiphora. Moreover, the excessive nasal fold has been trimmed away to prevent facial trichiasis with consequent nasal hair rubbing the cornea leading to pigmentary keratitis formation