Brachycephaly is an oculofacial condition affecting numerous popular dog breeds. In 2015, the American Kennel Club ranked the French and English Bulldogs in the top 10 most favorite dog breeds in North America. The brachycephalic skull is disproportionately shorter and wider than is typical for the species, resulting in a markedly shortened nose and upper jaw, and a “flattened face”. The bony orbits that usually surround and protect the eyes in other dog breeds, are very shallow in the brachycephalic, creating prominently positioned “or bulgy” eyes. While these extremes in conformation can be endearing to many dog lovers, brachycephalic dogs comprise a large percentage of our patient population in veterinary ophthalmology.
Here is summarized the most common vision threatening eye conditions that we encounter every day in these beloved breeds:
Lagophthalmia refers to the impaired ability to completely close the eyelids.
Impaired lid closure is attributed to shallow bony orbits and overly large (wide) eyelid openings. As a result, these dogs often sleep with their eyelids partially open. Some commonly affected breeds include the Shih Tzu, Pug, English Bulldog, Chinese Shar Pei, Pekinese, Cavalier King Charles Spaniel, Boston Terrier, and Lhasa Apso. This desiccation (drying out) of the eye surfaces leads to abnormal eye discharge and corneal inflammation (known as keratitis). The corneas develop blood vessels, become pigmented and scarred, which reduces vision.
To help combat the effects of lagophthalmia, daily use of viscous tear substitutes (eye lubricants) is highly beneficial. Several good products are available over the counter.
When eyelid closure is significantly impaired, there are several excellent surgical options to improve eye protection.
Tear deficiency or dry eye (keratoconjunctivitis sicca, KCS) develops more often in several brachycephalic dog breeds, including the English Bulldog, Pug, Lhasa Apso, Cavalier King Charles Spaniel, and Shih Tzu.
Eyes with KCS develop a thick (mucous) discharge, increased redness, and keratitis, that when uncontrolled or untreated results in vision loss.
Topical cyclosporine is very effective in stimulating tear production in dogs. Tacrolimus is also an excellent alternative. Liberal use of tear substitutes is highly beneficial.
ENTROPION AND TRICHIASIS
Entropion, which is inward rolling of the eyelid margins, is a common condition in brachycephalic dogs. Friction between the haired eyelid skin and the surface of the eye often results in corneal ulcerations (wounds). These ulcers are painful, and can become infected and erode deep into the cornea, with the potential for perforation. Chronic corneal irritation results in scarring and pigment deposit on the cornea. Prominent skin folds over the nose can also contact the eye with similar consequences.
While lubricating the eyes with ointments and antibiotics help to temporarily improve comfort, surgical repair of these conditions is often needed to eliminate skin-corneal contact and vision threatening complications.
While eye irritation and injury can develop for numerous reasons in brachycephalic dogs, when the keratitis persists or is recurrent, the deposit of corneal pigment (melanin) can be extensive, and is referred to as pigmentary keratitis. This effectively obstructs vision, and is like having “mud on your wind shield”.
Abnormal eyelashes, such as distichiasis, and ectopic cilia are also prevalent in several brachycephalic dog breeds, including the Shih Tzu, Pug and English Bulldog, and commonly contribute to the development of pigmentary keratitis.
However, one of the most significant causes of pigmentary keratitis in brachycephalic dogs is uncontrolled or severe forms of KCS. In fact, the combination of lagophthalmia and KCS appears to be the most devastating combination to vision, resulting in the most severe cases of pigmentary keratitis.
Brachycephalic dogs are inherently at higher risk for ocular trauma due to poor eye protection.
As such, only minor forms of trauma such as jumping off furniture, playing with other pets, or during routine bathing and grooming, can result in displacement of the eye from the orbit, termed proptosis of the eye.
Urgent medical treatment of ocular injuries is particularly crucial to maximize success in preserving vision. These animals typically have a combination of anatomic features and tear film deficiencies that not only results in a higher incidence of ocular trauma, but more severe forms of injury, and have an inherently compromised ability to heal them.
SUMMARY: Diligent and daily monitoring of the eyes in brachycephalic dogs is often crucial to identify ophthalmic disease or injury quickly, in order to institute vision preserving medical and/or surgical intervention.