Systemic adverse reactions in young Simmental calves following administration of a combination vaccine.

Combination vaccines containing viral and bacterial antigens are commonly used in veterinary practice and have been associated with adverse reactions. A group of young Simmental calves developed fever and depression following administration of a mixed vaccine, and 1 died with pulmonary edema, suggesting that endotoxins or other bacterial components may interact synergistically with some adjuvants to cause an enhanced pathologic inflammatory response in some individuals.