An outbreak of tuberculosis due toMycobacterium bovisinfection in a pack of English Foxhounds (2016-2017)

Abstract

Mycobacterium bovis can cause tuberculosis (TB) in social mammals including lions, cattle and man, but canine infections are considered rare. In 2016/17 we investigated a M. bovis TB outbreak in a pack of approximately 180 Foxhounds within the bovine TB Edge Area of England. We employed a combination of immunological tests including an interferon gamma release assay (IGRA) and a serological assay (DPP VetTB, Chembio). Test‐positive hounds were euthanased and subjected to post‐mortem examination (PME). Overall 164 hounds were tested; 97 (59%) responded positively to at least one test. Eighty‐five (52%) dogs responded to M. bovis antigens by IGRA while only 21 (12.9%) had detectable serological responses. At PME three hounds (3.1%) had visible lesions (VL) due to M. bovis infection, later confirmed by culture. Samples from 24 non‐VL hounds were cultured and M. bovis infection was confirmed in a further three hounds (11%). This study is the first investigation and report of an outbreak of M. bovis TB in a canine species. We establish that, in principle, diagnostic tests used for identifying infected individuals of other species can effectively be used in the dog. Further work is urgently needed to establish the sensitivity and specificity of the testing approach used in this study for future clinical application.

Bovine tuberculosis in working foxhounds: lessons learned from a complex public health investigation

“…Of the 164 hounds tested, 85 (52%) were diagnosed as being test positive as per the prospective case definition set [20]. Test positive hounds and clinically unwell hounds were euthanased and M. bovis infection was confirmed by culture in 14 cases.…”

“…Simultaneously, an epidemiological investigation began to identify the risk pathways by which the hounds may have initially become infected. These are detailed in [20] and comprised of, in order of considered likelihood; (a) movement of infected hounds into the kennels, (b) feeding M. bovis infected fallen stock to the hounds, (c) exposure to infected livestock or wildlife during work, and/or (d) exposure to infected local wildlife at the kennels.…”

Mycobacterium avium: an Emerging Pathogen for Dog Breeds with Hereditary Immunodeficiencies

“…Commercial collection tubes coated on the inner surface with the necessary stimulants enabling immediate exposure of viable lymphocytes to specific mycobacterial antigens are now available [90]. Different IGRAs have been successfully used in domestic dogs and other canidae to detect immunological sensitization to MTBC [20,90,91]. Similarly, IGRAs for the early diagnosis of Johne's disease caused by MAP showed promising results in farm ruminants [65,92,93].…”

“…The members of the MTBC are believed to be host-adapted and, with the exception of M. canettii which has a putative environmental reservoir, they can be found in contaminated environments. Dogs infected with M. tuberculosis, M. bovis, and M. microti have been rarely documented worldwide [9][10][11]. Therefore, dogs are considered a spillover host for MTBC pathogens, meaning that there is no maintenance of the pathogen within the canine population without continued exposure to a primary host and reservoir [12].…”

The Welfare of Pig-Hunting Dogs in Australia

“…The United Kingdom (UK) banned hunting with dogs in 2004 after widespread public outcry and a government inquiry that found severe animal welfare risks associated with the practice [16]. The role of hunting dogs in spreading infectious diseases through livestock and wildlife populations in the USA and UK has been highlighted recently, further fueling concerns about hunting practices in these countries [13,22]. Welfare concerns have also been raised about both the welfare of quarry species pursued by dogs [15,18,23,24,25,26,27,28,29,30] and the dogs themselves [15,16,23,25,26,27,29,30,31,32,33].…”