Sheep given vaccines develop autoimmune problems
Aluminum (Al)-containing vaccines are common in sheep management and they have been associated with the Autoimmune/inflammatory Syndrome Induced by Adjuvants (ASIA syndrome). The aim of this study was to investigate cognitive and behavioral changes in sheep subjected to a protocol of repetitive inoculation with Al-containing products. Twenty-one lambs were assigned to three groups (n = 7 each): A (Control), B (Adjuvant-only), C (Vaccine). Group C was inoculated with commercial Al-containing vaccines; Group B received the equivalent dose of Al only (Alhydrogel®) and Group A received PBS. Sixteen inoculations were administered within a 349-day period. Ethologic changes were studied in late summer (7 inoculations) and mid-winter (16 inoculations). Animals in groups B and C exhibited behavioral changes: affiliative interactions were significantly reduced and aggressive interactions and stereotypies increased significantly. They also exhibited a significant increase in excitatory behavior and compulsive eating. In general, changes were more pronounced in the Vaccine group than they were in the Adjuvant-only group. Some changes were already significant in summer, after seven inoculations only. This study is the first to describe behavioral changes in sheep after having received repetitive injections of Al-containing products, explaining some of the clinical signs observed in ovine ASIA syndrome.