Impact of Facial Conformation on Canine Health: Corneal Ulceration

Abstract

Concern has arisen in recent years that selection for extreme facial morphology in the domestic dog may be leading to an increased frequency of eye disorders. Corneal ulcers are a common and painful eye problem in domestic dogs that can lead to scarring and/or perforation of the cornea, potentially causing blindness. Exaggerated juvenile-like craniofacial conformations and wide eyes have been suspected as risk factors for corneal ulceration. This study aimed to quantify the relationship between corneal ulceration risk and conformational factors including relative eyelid aperture width, brachycephalic (short-muzzled) skull shape, the presence of a nasal fold (wrinkle), and exposed eye-white. A 14 month cross-sectional study of dogs entering a large UK based small animal referral hospital for both corneal ulcers and unrelated disorders was carried out. Dogs were classed as affected if they were diagnosed with a corneal ulcer using fluorescein dye while at the hospital (whether referred for this disorder or not), or if a previous diagnosis of corneal ulcer(s) was documented in the dogs’ histories. Of 700 dogs recruited, measured and clinically examined, 31 were affected by corneal ulcers. Most cases were male (71%), small breed dogs (mean± SE weight: 11.4±1.1 kg), with the most commonly diagnosed breed being the Pug. Dogs with nasal folds were nearly five times more likely to be affected by corneal ulcers than those without, and brachycephalic dogs (craniofacial ratio <0.5) were twenty times more likely to be affected than non-brachycephalic dogs. A 10% increase in relative eyelid aperture width more than tripled the ulcer risk. Exposed eye-white was associated with a nearly three times increased risk. The results demonstrate that artificially selecting for these facial characteristics greatly heightens the risk of corneal ulcers, and such selection should thus be discouraged to improve canine welfare.

Corneal ulcerative disease in dogs under primary veterinary care in England: epidemiology and clinical management

“…Previous studies on smaller, referral populations have also suggested that brachycephalic breeds and those non-brachycephalic breeds that also have prominent eyes could be overrepresented for CUD [7, 9, 31, 49]. Brachycephalic conformation has been associated with reduced numbers of corneal nerve endings [50].…”

Septic keratitis in dogs, cats, and horses in Switzerland: associated bacteria and antibiotic susceptibility

“…In this study, the Toy Terrier breed, with one individual representing the breed in the study population and 13 dogs representing the breed in the reference population (OR: 132.97, CI: 16.94–1043.32), is an example of a likely coincidentally increased OR with a wide CI suggesting great statistical uncertainty. Packer et al . reported that brachycephalism (20x), the presence of nasal folds (5x), a 10% increase in relative eyelid aperture width (3x), and exposed scleral tissue (3x) predispose dogs to the development of corneal ulceration by the multiplication factors listed between parentheses.…”

Bacterial Keratitis Risk Factors, Pathogens and Antibiotic Susceptibilities: A 5- Year Review of Cases at Dubai hospital, Dubai

“…Typical viral ulcers and healing ulcers were excluded. These will include Mooren's ulcers [14], marginal ulcers [15], interstitial keratitis [16], sterile neurotrophic ulcers [17], and any ulcers associated with autoimmune conditions. Inclusion criteria: All patients' data with a corneal scraping for culture over a 5-year period were included in this study.…”