Causes of abortion in Iranian goat herds and associated risk factors

Abstract

Abortion imposes a substantial economic burden on the global small ruminant industry, not only reducing herd productivity but also contributing to the spread of zoonotic diseases. This study examines the primary factors associated with abortion, both infectious and non-infectious, in 623 goat herds across Iran. A comprehensive evaluation was performed, incorporating herd history, laboratory results, and statistical analyses using univariate tests and multivariable binary logistic regression. Key findings revealed significant associations with abortion, including previous abortion history, gestational age of the aborted foetus, routine veterinary visits, mineral supplementation, and vaccination practices. Non-infectious factors, such as pregnancy toxemia, goiter, and deficiencies in vitamin E/selenium, were identified in herds with a low abortion prevalence (<10 %). Among the 623 herds studied, 277 (44.5 %) exhibited an abortion prevalence below 2 %, considered within normal limits, while the remaining 346 herds (55.5 %) experienced pathological abortion rates exceeding 2 %. The definitive cause of abortion was determined in 227 of the 346 abortion outbreaks analysed, accounting for 65.6 % of the cases. Infectious agents were identified in 40.7 % of the herds with abortion rates exceeding 2 %, with Brucella melitensis (9.5 %), Chlamydia abortus (7.8 %), and Coxiella burnetii (5.2 %) being the most prevalent pathogens. Multivariable binary logistic regression analysis revealed significant associations between abortion and several factors, including birth (OR=2.01, 95 % CI: 1.05–3.89, P=0.036), previous abortion history (OR=14.5, 95 % CI: 6.01–37.3, P<0.001), gestational age of the aborted foetus (OR=3.07, 95 % CI: 1.63–5.89, P<0.001), routine veterinary visits (OR=0.16, 95 % CI: 0.09–0.27, P<0.001), vaccination (OR=0.25, 95 % CI: 0.11–0.53, P<0.001), and mineral supplementation (OR=0.36, 95 % CI: 0.21–0.62, P<0.001). These findings underscore the diverse causes of abortion in Iranian goat herds, emphasizing the need to improve farmer awareness and access to commercial vaccines targeting infectious abortion agents to enhance herd productivity.