Antler cannibalism in reindeer

Abstract

Prion diseases constitute a class of invariably fatal and degenerative encephalopathies. Chronic Wasting Disease (CWD) is a contagious prion disease among cervids, which is spreading and causing marked population declines in USA and Canada. The first outbreak of CWD in Europe was discovered in a reindeer population in Norway in 2016. In the worst-case scenario with continental-wide spreading of CWD in Eurasia, an annual harvest of around 4 million cervids is at stake only in Europe, with huge economic and cultural significance. An in situ origin of CWD was suspected, and it appear urgent to identify the likely cause to prevent future emergences. Here, we document the novel phenomenon of extensive antler cannibalism prior to shedding among reindeer in the CWD-infected population. The extent of antler cannibalism increased over the last decades when CWD emerged, and included ingestion of vascularized antlers. Ingestion of tissues from conspecifics is a risk factor for the emergence of prion diseases, where the presence of extensive antler cannibalism opens the intriguing possibility of a ‘Kuru-analogue’ origin of CWD among the reindeer in Europe. Based on general insight on pathology of prion diseases and strain selection processes, we propose an hypothesis for how contagious CWD may emerge from sporadic CWD under the unique epidemiological conditions we document here. More research is required to document the presence of prions in reindeer antlers, and whether antler cannibalism actually led to a strain selection process and the emergence of a contagious form of CWD from a sporadic form of CWD.

Review on PRNP genetics and susceptibility to chronic wasting disease of Cervidae

“…Edible tissues in which PrP CWD has been detected are heart, liver, kidney, tongue, pancreas, blood, adipose tissue, lymphoreticular system and antler velvet [6][7][8][9][10][11]. An increasing phenomenon of antler cannibalism was recently quantified among the affected reindeer population from Norway and found to potentially contribute to CWD emergence [12]. CWD prions bound to soil components where TSE-infected animals stood, persist for many years (at least 16 years for scrapie sheep [13]) and remain infectious by the oral route of exposure [14].…”

Age estimation in the harbour seal (Phoca vitulina) based on the closure of skull sutures and synchondroses

“…Differences in condylobasal length and SCS between adult (≥5 years) male and female harbour seals were analysed with t ‐tests for independent samples. The use of parametric methods for the analysis of sum scores (here SCS) based on ordinal (Likert scale) data is considered appropriate (Norman, 2010), and these methods have previously been used in other studies on such data (e.g., Mysterud et al, 2020; Oh et al, 2019; Stewardson et al, 2011a, 2011b). Statistical tests were performed with the software package Statistica, version 13.3 (Tibco Software), and in all tests, p ‐values <0.05 were considered significant.…”

Chronic wasting disease: a cervid prion infection looming to spillover

“…The presence of CWD infectivity in antler velvet [ 61 ] leads to the question of whether prions can persist in the calcified antler and favor male to male intradermal inoculation during the rut, or represent a risk factor in terms of oral CWD transmission, as antler gnawing is common among cervids. Antler gnawing has been suggested as a factor involved in the transmission of CWD in the reindeer population from Nordfjella, Norway [ 62 ].…”