Breed and conformational predispositions for prolapsed nictitating membrane gland (PNMG) in dogs in the UK: A VetCompass study

• Published in: PloS one Vol. 17; no. 1; p. e0260538
• Main Authors: Dan G O'Neill, Yahui Yin, Roser Tetas Pont, Dave C Brodbelt, David B Church, Camilla Pegram, Minna Mustikka
• Format: Journal Article
• Language: English
• Published: Public Library of Science (PLoS) 01.01.2022
• ISSN: 1932-6203
• DOI: 10.1371/journal.pone.0260538

BackgroundProlapsed nictitating membrane gland (PNMG) is the most common disorder of the third eyelid in dogs. However, the epidemiology of PNMG in the wider dog population remains understudied.MethodsUsing de-identified clinical data from the VetCompass Programme, this cohort study aimed to report the prevalence, demographic and breed-related risk factors of PNMG in dogs attending UK primary care veterinary practices in 2016.ResultsThere were 1,802 PNMG cases identified from 905,543 dogs, yielding an annual prevalence of 0.20% (95% confidence interval (CI) 0.19-0.21). The median age at first diagnosis was 0.63 years (IQR 0.33-1.98, range 0.11-18.00). Dogs aged under 1 year had 10.82 times the odds (95% CI 9.17-12.76) compared with dogs aged from 2 to under 4 years. Neutered animals had higher odds than entire animals within both sexes. Breeds with the highest odds of PNMG compared with crossbred dogs included Neapolitan Mastiff (odds ratio (OR) 34.26, 95%CI 15.92-73.75), English Bulldog (OR 24.08, 95% CI 20.62-28.13), Cane Corso (OR 14.66, 95% CI 8.18-26.28), Lhasa Apso (OR 12.37, 95% CI 10.26-14.92) and American Cocker Spaniel (OR 11.57, 95% CI 5.59-23.96). Purebred dogs had 1.43 times the odds (95% CI 1.26-1.63) of PNMG compared with crossbreed dogs. Breeds with brachycephalic skull conformation had 6.71 times the odds (95%CI 5.89-7.64) compared with breeds with mesocephalic skull conformation. Insured dogs had 1.89 times the odds (95% CI 1.65-2.16) compared with uninsured dogs.ConclusionsThis study reports the largest cohort of primary-care PNMG cases assembled to date. The results showing young age at diagnosis along with the breed, purebred and brachycephalic skull conformation predispositions suggest a hereditary involvement in PNMG development. These results may help to guide breeding strategies to reduce the prevalence of PNMG and improve welfare in predisposed individuals.