Lenticular lesions in harbour seals (Phoca vitulina)

Lenticular lesions were found in 21 of 44 mainly younger harbour seals investigated during the epidemic caused by phocine distemper virus (PDV) in 1988/89. Malformations and cataracts varied in quality and degree and were histologically characterized by proliferative and/or degenerative lenticular alterations. Except for two animals, both eyes were affected symmetrically. For that reason, local exogenous causes are improbable. There was very little evidence for infectious agents isolated from the seals investigated (viruses, in particular PDV, bacteria, mycoplasma, parasites). Environmental, dietary and hereditary aspects were also considered, but no final conclusions could be made as to the involvement of these factors in the genesis of lens lesions in harbour seals.