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

Abstract

Background 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. Methods 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. Results 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. Conclusions 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.

English Bulldogs in the UK: a VetCompass study of their disorder predispositions and protections

“…Consequently, understanding the development of conformation-related disease within the breed, and accurately documenting the disease burden and predispositions within the current breed population [ 6 ] are key to assessing and, if possible, redressing some of the main health issues in English Bulldogs. In line with the study hypothesis, the four predispositions with the highest odds in English Bulldogs are all directly associated with the extreme conformation that defines the English Bulldog breed: skin fold dermatitis (× 38.12) [ 8 ], prolapsed nictitating membrane gland (× 26.69) [ 45 ], mandibular prognathism (× 24.32) [ 8 ] and BOAS (19.20) [ 14 ]. This evidence supports calls for urgent action to redefine the English Bulldog away from its current extreme conformation and instead to move the breed rapidly towards a moderate conformation on welfare grounds.…”

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

“…A recent study that investigated the epidemiology of prolapsed gland of the third eyelid in various breeds reported an annual prevalence 0.2% in a total of 1802 affected cases out of a population of 905 543 dogs 100 . While the authors reported that non‐brachycephalic breeds such as Neapolitan Mastiff and Cane Corso had increased odds of developing prolapsed gland of the third eyelid (odds ratios of 34.26 with a 95% CI: 15.92–73.75 and 14.66 with a 95% CI: 8.18–26.28, respectively), they also found that the English bulldog and Lhasa Apso also had increased odds (odds ratios of 24.08 with a 95% CI: 20.62–28.13, and 12.37 with a 95% CI: 10.26–14.92, respectively), and that brachycephalic breeds had much higher odds (6.71 times the odds; 95% CI: 5.89–7.64) compared with mesocephalic breeds 100 …”

“…A majority of studies of ocular surface diseases in dogs are based on referral populations (i.e., specialty care population), 5,21,39,48,72,73,96,104 and few studies focus on general practice populations, [69][70][71]100,105 while very few also include show-animals. 22,79 There are inherent biases with the use of first-line practice data, but there are also biases in the exclusive use of referral cases, as described previously.…”

Dental disease in companion rabbits under UK primary veterinary care: Frequency and risk factors

“…It is also noteworthy that the current results relate to only one disorder, so it is still possible that these exaggerated conformations are associated with one or more other health issues, as identified in dogs (e.g., Ref. 70).…”

“…Although the multivariable modelling accounts for demographic variables available to the current study, other factors such as diet, housing and insurance status were not accounted for. Insured dogs are reported with significantly higher odds of multiple diseases, suggesting high levels of diagnostic bias, 35,70,82 and a similar effect may exist for insured rabbits. Data were on the body condition score of rabbits were not available in the current study, so the presence or levels of obesity could not be considered in the analysis.…”