Health and Mortality Monitoring in Threatened Mammals: A First Post Mortem Study of Otters (Lutra lutra L.) in Italy

Abstract

Dead specimens provide valuable data for the conservation of threatened species, allowing investigations of mortality, health conditions, and demographic parameters. The Eurasian otter (Lutra lutra) is a semiaquatic carnivore listed as endangered in Italy. In 2009, we started the first post mortem (PM) study of otters in Italy, through collaborative research between mammal ecologists and veterinary pathologists, using standardized protocols. Twenty-eight otters, mostly collected between 2009 and 2017, were examined. Most otters were males (67%), between 1 and 3 years old (64%), and predominantly in good nutritional condition. Adult males were significantly larger than adult females (p < 0.02), as expected for the species, although both sexes appeared to be smaller than otters examined in Central–northern Europe. The youngest sexually mature female was 3 years old. Road traffic collisions were the major cause of death, especially in young individuals, and mainly occurred in autumn–winter, particularly for females. Investigations of the scene of death contributed to revealing factors forcing otters to travel out of the water and move over the road, suggesting appropriate measures to reduce vehicle collision risk. Other causes of death included blunt chest trauma of uncertain origin, dog and conspecific attacks, or diseases of infectious or non-infectious origin, such as ulcerative gastritis, pleuropneumonia and peritonitis. Other diagnosed diseases included lymphoma. Ecto- and endoparasites were rarely detected, although we report the first documentation of heartworm and Ixodes hexagonus infestation in Italian otters. It is important to continue comprehensive, standardized PM investigations of otters in Italy to define baseline health, biometric and demographic parameters, collect biological samples for comparative analyses, and to reduce road-kill mortality. The present study suggests that the timely collection of carcasses and collaborative and coordinated research efforts are essential for obtaining useful data for the conservation of otters.

Wild Mesocarnivores as Reservoirs of Endoparasites Causing Important Zoonoses and Emerging Bridging Infections across Europe

“…The otter has occasionally been found as infected with D. immitis [ 168 , 362 , 363 ]. However, its factual reservoir role is unknown, as microfilaraemia was documented in only one case [ 168 , 362 , 363 ].…”

“…The otter has occasionally been found as infected with D. immitis [ 168 , 362 , 363 ]. However, its factual reservoir role is unknown, as microfilaraemia was documented in only one case [ 168 , 362 , 363 ]. Further investigations are needed to clarify the role of otters as a source of infection for dogs and other hosts in the same area.…”

A Review of Non-Invasive Sampling in Wildlife Disease and Health Research: What’s New?

“…Wildlife disease and health surveys often rely on the opportunistic sampling of carcasses, and this is certainly an important resource for passive disease surveillance (e.g., [17][18][19][20] in the present Special Issue), but it can introduce relevant biases into epidemiological studies [21]. Random sampling of living individuals should therefore be preferred whenever researchers are interested in studying disease circulation in natural populations [22].…”

Wildlife Disease Monitoring: Methods and Perspectives

“…Whatever the scope of disease monitoring, and especially in a conservation context, opportunistic sampling is sometimes the only strategy available to obtain information on the health status of wild animal populations. Rohner et al [ 7 ] and Fusillo et al [ 8 ] apply standardised post-mortem protocols on opportunistically collected carcasses to investigate causes of mortality in Eurasian otter ( Lutra lutra ) populations in the north of Germany and the south of Italy, respectively. The Eurasian otter is an elusive mammal classified as near threatened globally (IUCN Red List), and these contributions therefore offer some useful insights to better target conservation efforts.…”