Crowding and winter emergency feeding as predisposing factors for kerato-conjunctivitis in semi-domesticated reindeer...

Due to the hard environmental and climatic situation in late winter 1999, a herd of about 200 free-ranging, semi-domesticated reindeer was gathered in a paddock in northern Norway for emergency feeding. About the same number of reindeer was not corralled but supplementary fed on their winter pastures. The fodder was of relatively good quality but very dusty and fed in a very dry environment. Six weeks later, an outbreak of eye-infection was diagnosed in one third of the corralled reindeer; mild symptoms were observed in most of them, but 11 animals showed severe signs of disease. No signs of disease were found in the non-corralled animals. Ten reindeer died through emaciation, the eleventh was sacrificed. Histopathological diagnosis of two severely affected eyes revealed a severe purulent kerato-conjunctivitis with bacteria and plant particles embedded in purulent exudates on the cornea and conjunctiva. In one eye from the two most affected animals Actinomyces pyogenes, coagulase-negative Staphylococci and Escherichia coli and in the other one Staphylococcus aureus and Escherichia coli were found. The bacteria encountered in this study are not considered the primary cause of disease. They seem rather to be opportunistic infectious agents of eyes that have been irritated mechanically through exposure to dusty fodder in a dry environment. The stress through unfamiliar corralling of the reindeer, that followed an insufficient fodder supply, could be considered as an additional infection supporting factor. This case-report emphasises on the importance of different factors involved in favouring outbreaks of disease in reindeer, under intensified husbandry conditions. Even though crowding and emergency feeding may be, at certain circumstances, the only means of survival for reindeer, a negative impact of implied crowding diseases on their productivity, must be considered, as well.