The pandemic of ocular surface disease in brachycephalic dogs: The brachycephalic ocular syndrome

Abstract

Brachycephalic dog breeds are popular around the world, yet many brachycephalic dogs are affected by numerous health problems, including several headrelated diseases that are directly linked to their conformation. In addition to the well-recognized disorders associated with the respiratory system (brachycephalic obstructive airway syndrome, i.e., BOAS), brachycephalic dogs have a concerningly high prevalence of ocular surface disorders that can cause chronic discomfort, loss of the globe, and/or require long-term, daily therapy. This review offers a summary of the physiological and anatomical features of brachycephalic ocular syndrome (BOS) that predispose brachycephalic dogs to develop ocular surface disease, followed by a concise description of common ocular diseases associated with BOS. It ends with an overview of evidence-based guidelines and animal welfare legislation that some in the veterinary community have already implemented but that requires a wider, international effort in order to reduce the prevalence of BOS-associated disorders and improve the ocular health of affected dogs.

Comprehensive Review of Canine Entropion: Types, Surgical Techniques, and Prognosis

“…Entropion is an ophthalmic condition characterized by the partial or complete inversion of the eyelid margin and is a highly prevalent disease in dogs [1,2]. A study by O'Neill et al [3], revealed that out of a population of 455,557 patients, the prevalence of entropion is 17.88%.…”

Shih-Tzu dogs show alterations in ocular surface homeostasis despite adequate aqueous tear production

“…The most common alteration in the PTF in dogs is dry eye disease (DED), which can occur due to inadequate tear film production or excessive evaporation [ 17 , 18 ]. In relation to breeds, brachycephalic dogs have anatomical and physiological characteristics that predispose them to development of ocular diseases, such as brachycephalic ocular syndrome [ 19 , 20 ]. Shih-Tzu dogs are particularly affected by this syndrome, especially those related to PTF [ 20 ].…”

“…This breed has grown in popularity in recent years and was ranked as the 20th most popular out of 191 breeds in 2020 by the American Kennel Club [ 21 ]. Due to the anatomical configuration of its skull, which leads to greater exposure of the eyeball, conditions such as caruncular trichiasis [ 20 ], medial lower eyelid entropion [ 20 ], exophthalmos [ 22 ], lagophthalmos [ 20 , 23 ], DED [ 22 ], and corneal ulcers [ 17 ] are frequently reported [ 19 ]. As a result of disturbances in tear production or increased tear evaporation, Shih-Tzu dogs can show clinical signs, such as those related to DED, leading to loss of vision [ 19 , 24 , 25 ].…”

A Review of Clinical Outcomes, Owner Understanding and Satisfaction following Medial Canthoplasty in Brachycephalic Dogs in a UK Referral Setting (2016–2021)

“…Brachycephalic dog breeds are reported to have twenty times increased risk in corneal ulceration compared to non-brachycephalic breeds and have increased risk of deep stromal involvement [ 2 , 5 ]. This may be associated with persistent conformation abnormalities, compromised tear film and reduction in corneal sensitivity [ 2 , 5 , 6 , 7 ]. Corneal grafting procedures are over-represented in brachycephalic breeds [ 8 , 9 , 10 , 11 , 12 ].…”

“…While the evidence for a negative impact from BOS on health and welfare is strong, the appealingly large eyes and short nose of brachycephalic breeds are still considered desirable traits for many owners [ 6 ]. There is ongoing investigation to try to understand the emotional reasoning behind purchasing a breed with known disease predispositions detrimental to their welfare, including cultural (e.g., fashion) drivers, as well as biological drivers (e.g., the ‘cute effect’ due to their baby-like facial appearance) [ 32 , 33 , 34 , 35 ].…”