[1] Univ Fed Rio Grande do Sul, Hosp Clin Vet, BR-91540000 Porto Alegre, RS, Brazil
[2] Univ Fed Rio Grande do Sul, Programa Posgrad Ciencias Vet, BR-91540000 Porto Alegre, RS, Brazil
[3] Pontificia Univ Catolica Rio Grande Sul PUCRS, Hosp Vet, Uruguaiana, RS, Brazil
[4] Purdue Univ, Dept Vet Pathobiol, W Lafayette, IN 47907 USA
[5] Univ Fed Rio Grande do Sul, Fac Vet, BR-91540000 Porto Alegre, RS, Brazil