Infectious Disease Outbreak Associated With Supplementary Feeding of Semi-domesticated Reindeer.

Morten Tryland,Ingebjørg H Nymo,Ulrika Rockström,Torill Mørk,Javier Sánchez Romano,Jörn Klein

doi:10.3389/fvets.2019.00126

Abstract

Supplementary winter feeding of semi-domesticated reindeer (Rangifer tarandus tarandus) has become more common in Sweden and Norway due to reindeer pasture fragmentation and climatic conditions. With increased corralling and feeding, often associated with animal stress, increased animal-to-animal contact, and poor hygienic conditions, an altered range of health challenges and diseases may emerge. An outbreak of three different infectious diseases appeared simultaneously in a reindeer herd in Norrbotten County, Sweden. The animals were corralled and fed silage. Several animals in poor body condition stopped eating, with drool and discoloration of the hair coat around the mouth. There were large, black, necrotic lesions on the tongue and gingiva, with holes perforating the chin, indicative of oral necrobacillosis and Fusobacterium spp. infection. Simultaneously, animals were seen with proliferative lesions in the oral mucosa and on the lips, characteristic of contagious ecthyma and Orf virus infection. Furthermore, three animals had keratoconjunctivitis suggesting exposure to cervid herpesvirus 2 (CvHV2) and possibly secondary bacterial infections. DNA specific for Fusobacterium necrophorum and ORFV was detected in relevant tissue samples. Antibodies against CvHV2 were detected in 10 of 13 diseased and in four of 11 apparently healthy reindeer. Nine animals were found dead or were euthanized during the outbreak. Health risk factors associated with feeding and corralling may severely impact animal welfare and the herder's economy, and may represent an underestimated cost when replacing natural grazing with feeding.

Highlights

In Sweden and Norway, semi-domesticated reindeer (Eurasian tundra reindeer; Rangifer tarandus tarandus) are for most part of the year free-ranging, grazing on vast, and remote mountain pastures
The diagnosis of contagious ecthyma, necrobacillosis, and transmissible eye infections are often based on clinical observations only, and this is the first report of all three diseases being verified and evaluated during the same disease outbreak, indicating that these infections may have interacted with each other
In contrast to Fusobacterium spp., which is present in the intestinal microbiota of reindeer, and to cervid herpesvirus 2 (CvHV2) which is enzootic in the Fennoscandian reindeer herds, it is assumed that parapoxvirus, such as ORFV, is not enzootic in Norwegian and Swedish reindeer populations

Summary

INTRODUCTION

In Sweden and Norway, semi-domesticated reindeer (Eurasian tundra reindeer; Rangifer tarandus tarandus) are for most part of the year free-ranging, grazing on vast, and remote mountain pastures. We present a disease outbreak in Norrbotten County, Northern Sweden, in March 2016, in a herd of semi-domesticated reindeer corralled for winter feeding, displaying necrotizing, and proliferative mucosal and skin lesions as well as eye infections. Bilateral eye infections (i.e. keratoconjunctivitis, pus discharge, and periorbital edema) were observed by the veterinarian in three animals (Table 1, 1V, 6V, and 11V) (Figure 1C) These three had all been corralled in HC and had no clinical signs of necrobacillosis or contagious ecthyma. PCRs targeting parapoxvirus, B2L and GIF gene regions, were conducted [31] on seven swab samples from mucosal membranes and three tissue samples from animals with mouth mucosal lesions consistent with contagious ecthyma (n = 9) and necrobacillosis (n = 4).

DISCUSSION

Findings

ETHICS STATEMENT