Pathological findings in stranded seals (Phoca vitulina and Halichoerus grypus) in Noord-Holland and Texel (2011-2012)
Summary
An overview is created of the pathological findings from post mortem examination on 27 seals. 25 Of the seals were of the species Phoca Vitulina (harbor seal). In one case the species remained unknown while the head was missing. One seals was of the species Halichoerus grypus (grey seal). The seals used for this research project were either found dead on the shore or died at the animal rehabilitation centre on Texel, Noord-Holland, Ecomare. The seals varied in age, sex, date and place of stranding and whether or not euthanasia was performed.
After performing the necropsy with macroscopical evaluation, and in five cases histological research, a cause of death was determined. In five animals also histological findings were available. Twelve seals died of euthanasia (44,4%), four because of lungworm (14,8%), four seals suffered from trauma (14,8%), in four cases the cause of death was grouped as ‘others’ (14,8%) and in three cases the cause of death remained unknown (11,1%).
Euthanasia was always performed because of lungworms (Otostrongylus circumlitis and Parafilaroides gymnurus). With a total of 16 seals suffering from lungworm, this was determined to be the cause of death of the greatest significance. These seals were all juvenile and in a bad to moderate nutritional condition. The main macroscopical findings in the respiratory tractwere: decreased and irregular consolidation, colourful aspects, emphysema and hyperaemia and hemorrhagic fluid in the lungtissue and bronchia. No correlation between the severity of the infection, damage to the lungtissue and the amount of worms was found. Further research will be needed.
A total of 23 seals were infected with parasites anywere in the body. None of the seals used in this studie died from an infection with parasites other than the lungworm species.