Pathology of new world camelids in Ireland: 13 years of disease surveillance and the significance of bovine tuberculosis in alpaca

Abstract

Causes of New World Camelid (168 alpacas; 7 llamas) mortality in Ireland based on review of passive surveillance findings of the Irish Veterinary Laboratory Service from 2010 till 2023 were analysed. The most frequently submitted age group were adults (58.8 %), followed by juveniles (20.6 %), crias (16.6 %), and aborted foeti (4 %). Regardless of age, 96 % were suitable for investigation, with identified aetiology in 77.4 % of cases. The pathology was systemic (30.9 %) or involving the alimentary (39.3 %), respiratory (8.9 %), urogenital (4.9 %), musculoskeletal and lymphatic (2.2 % each), integument (1.8 %), cardiocirculatory (1.3 %), nervous (0.9 %) system; 7.6 % were inconclusive. The aetiology was bacterial (44.4 %), parasitic (24.3 %), nutritional/metabolic/toxic (6.4 %), traumatic/mechanical (3.2 %), congenital (1.6 %), and neoplastic (0.5 %), while 19.6 % had unknown aetiology. The diagnostic rate was highest in crias (79.3 %) and lowest in the abortion group (0 %). Crias had mainly systemic and alimentary tract diseases (43.3 % and 26.6 %, respectively); juveniles had mainly alimentary illness and systemic diseases (51.3 % and 30.7 %, respectively); similarly for adults (40.2 % and 25.5 %, respectively). The primary aetiology detected was bacterial (45.5 %, 35.1 %, and 48.7 % for crias, juveniles and adults, respectively). Mycobacterium bovis was identified in 27.4 % of submissions, 25 % of which had lesions localised to a single organ (mainly lung), whilst 75 % had generalised tuberculosis, where the lung and liver were the most and second most commonly affected organs, respectively. Fasciola hepatica infection represented the second most common cause or co-cause of mortality. To the authors' knowledge, this is the most extensive published case series of M. bovis pathology in alpacas.