A retrospective study of causes of mortality in free ranging red deer (Cervus elaphus) in Belgium 2010-2014

Studies based on wildlife necropsy provide valuable information on present and new diseases as well as environmental factors influencing wildlife health. The objective of this study was to report the results of 190 red deer... [ view full abstract ]

Studies based on wildlife necropsy provide valuable information on present and new diseases as well as environmental factors influencing wildlife health. The objective of this study was to report the results of 190 red deer pathologic examinations. One hundred and nine of them were found dead whereas the others (n= 81) were shot for sanitary reasons. The study 2010-2014 was included in a control plan targeting paratuberculosis (PTB) in wild cervids. The field collaborators were informed about PTB and motivated to transmit to the Surveillance Network any suspected case. Postmortem examinations were performed according to a standardised protocol. Targeted tissues were selected for specific histopathological, microbiological, or parasitological analysis and X-ray examinations were realised. In diarrheic animals, research of Mycobacterium avium subspecies paratuberculosis (culture and PCR) was systematically attempted. Regarding the found dead animals (n = 109), the distribution of causes of death was as follows: traumatic 62/109, infectious 20/109, parasitic 10/109, miscellaneous 9/109 and undetermined causes 8/109. Traumatic injuries involved road accidents and poaching trials whereas the main infectious cause of death was PTB (14/20), other infectious diseases (6/20) included enterotoxemia, pasteurellosis, septic arthritis and meningoencephalitis. The 10 cases of heavy parasitism mainly involved lungworms infestations and miscellaneous cases included ingestion of foreign bodies. Among culled animals for ethic or sanitary reasons (n = 81), the two principal causes were traumatic injuries (n = 40) and infectious diseases (n = 34, including 30 cases of PTB). Other causes, including neoplasms, were anecdotal. Overall, after road injuries, infectious diseases are the major causes of mortality in free ranging red deer in Belgium. The control plan PTB is properly planned and field collaborators regularly bring cases for analysis. Furthermore, selective culling of PTB suspected cases allows to eliminate potential excretors and in this way prevents the disease from spreading.