Growth Performance and Clinicopathological Analyses in Lambs Repetitively Inoculated with Aluminum-Hydroxide Containing Vaccines or Aluminum-Hydroxide Only

Aluminum (Al) hydroxide is an effective adjuvant used in sheep vaccines. However, Al-adjuvants have been implicated as potential contributors to a severe wasting syndrome sheep—the so-called ovine autoimmune-inflammatory induced by adjuvants (ASIA syndrome). This work aimed characterize the effects of repetitive injection Al-hydroxide containing products lambs. Four flocks (Flocks 1–4; n = 21 each) kept under different conditions were studied. Three groups seven lambs (Vaccine, Adjuvant-only, and Control) established each flock. Mild differences average daily gain fattening index observed, indicating reduced growth performance Vaccine groups, likely related short-term episodes pyrexia decreased intake. Clinical hematological parameters remained within normal limits. Histology showed no significant between although there was tendency present higher frequency hyperchromatic, shrunken neurons lumbar spinal cord Adjuvant-only group. Although linked granulomas at site behavioral changes sheep, results experimental indicate that injected not enough fully reproduce presentation ASIA syndrome. Other factors such sex, breed, age, production system, diet or climate could play role.