[1] Univ Milan, Dept Vet Med, Via Celoria 10, I-20133 Milan, Italy
[2] Univ Complutense Madrid, Fac Vet Sci, Dept Anim Hlth, SALUVET, Ciudad Univ S-N, E-28040 Madrid, Spain
[3] Ist Zooprofilatt Sperimentale Lombardia & Emilia, Via Celoria 10, I-20133 Milan, Italy