Fresh whole blood samples were collected into EDTA tubes from 28 Biellese sheep belonging to three different farms. The animals included in the study were unrelated. Sheep were submitted to clinical evaluation by a veterinarian and categorized as control animals (n = 18), not showing any clinical sign, and disease-stressed animals (n = 10). Specifically, they had chronic diarrhoea (n = 5), lameness (n = 2), abscesses (n = 2) and respiratory syndrome (n = 1). The blood samples from disease-stressed sheep were collected twice: the first sampling was carried out in August, when the environmental temperature was of 35 °C, and the second in September with an environmental temperature of 26 °C. Every sampling was preceded by clinical evaluation of sheep to confirm disease status. The blood samples were immediately transferred to the lab and submitted to nucleic acid isolation.