Ocular Surface Characteristics in Pugs with Pigmentary Keratitis in the Canary Islands, Spain

Simple Summary The problem addressed in this study is the development of pigmentary keratitis (PK) in Pug-breed dogs, a condition characterized by corneal pigmentation and associated with ocular manifestations and vision loss. The aim of the study was to assess the occurrence of PK in Pug dogs, identify predisposing factors, and evaluate the tear film quantity and quality in affected dogs. The study found that the prevalence of PK was high in dogs, with 94.5% of eyes showing PK. The severity of corneal pigmentation varied, with very mild (20.3%), mild (16.4%), moderate (38.2%), and severe (25.1%) categories observed. Age and previous ocular diseases were identified as potential risk factors for the development of severe PK. The main conclusion of the study is that PK in Pug-breed dogs in the Canary Islands has a high prevalence and may have a genetic basis. Our most relevant contribution is the evaluation based on the Tear Break-Up Time (TBUT) test and the Tear Ferning Test (TFT). This information can be valuable to society by helping veterinarians diagnose and treat PK in Pugs and potentially prevent the disease through genetic screening and breeding practices.Abstract This study investigated the prevalence of pigmentary keratitis (PK) in Pug-breed dogs and described the ocular surface characteristics associated with this disease. A total of 219 eyes from 110 dogs were examined, with 94.5% of them affected by PK. Age, previous ocular diseases, corneal vascularization, and corneal sensitivity were significantly associated with the presence of PF and the severity of corneal pigmentation. The study also found that low tear production and blinks incomplete with tear signs, as well as reduced corneal sensitivity, were linked to more severe forms of corneal pigmentation. The Tear Ferning Test (TFT) was identified as a valuable tool for evaluating tear quality in dogs, with worse test results indicating a higher risk of severe PK. A lower mean Tear Break-Up Time (TBUT) test was observed in dogs with PK. Additionally, the study observed a statistically significant difference in corneal thickness between the nasal and temporal zones, with the nasal zone being thicker. It was also suggested that sex and fertility status may influence the incidence of PK and the severity of corneal pigmentation. Overall, these findings provide insight into the underlying causes of PK in Pugs and can inform future treatment strategies for this breed.