Abstract

In order to better understand risk factors for corneal diseases in pinnipeds housed at the Aquarium du Québec, we conducted a study evaluating associations between clinical manifestations of corneal diseases and different environmental parameters. Three grey seals (Halichoerus grypus), three harp seals (Phoca groenlandica), and three walruses (Odobenus rosmarus), housed in outdoor enclosures with pools supported by a single recirculating saltwater filtration system, were evaluated daily during 31 months for the presence of corneal opacities and blepharospasm. Eleven water parameters were regularly monitored (pH, alkalinity, salinity, hardness, temperature, [free chlorine], [total residual chlorine], [potassium], [nitrite], [nitrate] and [ammonium]). Data on daily air temperature, rain, snowfall, snowmelt, ground snow coverage, and global solar radiation were obtained from Environment Canada for the area. Using multiple linear regression models, the following statistically significant associations were detected. For grey seals: Blepharospasm with high global solar radiation (P = 0.003); corneal opacities with high alkalinity (P = 0.001). For harp seals: Corneal opacities with high pH (P = 0.02). For walruses: Blepharospasm with low levels of potassium (P = 0.008); corneal opacities with low pH (P = 0.01). Incidental associations were observed between low salinity and blepharospasm in harp seals, but overall this was not statistically significant association. These associations, although not necessarily causal, provide avenues for environmental modifications that might contribute to minimize the occurrence of these ocular issues, such as providing additional shading, increasing water potassium levels, and minimizing variations in pH and alkalinity.