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

O'Neill, Daniel; Yahui, Yin; Roser, Tetas Pont; Dave C., Brodbelt; David B., Church; Camilla, Pegram; Minn, Mustikka


Daniel O'Neill

Yin Yahui

Tetas Pont Roser

Brodbelt Dave C.

Church David B.

Pegram Camilla

Mustikka Minn


Prolapsed 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.

Using 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.

There 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.

This 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.


O'Neill, D., Yahui, Y., Roser, T. P., Dave C., B., David B., C., Camilla, P., & Minn, M. (2022). Breed and conformational predispositions for prolapsed nictitating membrane gland (PNMG) in dogs in the UK: A VetCompass study. (Con)textos Linguísticos, 17(1),

Journal Article Type Article
Acceptance Date Jan 6, 2022
Online Publication Date Jan 26, 2022
Publication Date Jan 26, 2022
Deposit Date Apr 4, 2021
Publicly Available Date Jan 27, 2022
Journal PLOS ONE
Publisher Universidade Federal do Espírito Santo
Peer Reviewed Peer Reviewed
Volume 17
Issue 1
Public URL
Publisher URL


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