AbstractA case of adverse post‐vaccination allergic reactions, which occurred in a dairy cattle herd 8 days after the annual foot‐and‐mouth disease (FMD) vaccination, is described. The dermatologic lesions observed in these cattle included: urticaria, exudative and necrotic dermatitis, along with oedema and vesicles on the teats. These reactions occurred in 11.3% of the heifers, in 10% of the first‐lactating cows and in 14.6% of the adult cows. The average loss of milk production for an affected cow on this farm was 21.5% per day, for seven consecutive days. The extent of the lesions was apparently related to concurrent diseases such as bovine virus diarrhea – mucosal disease complex (BVD–MD) and Johne’s disease and, to a lesser degree, correlated with the age or breed.