Food Production Daily, an online food producer's news service, wrote in its Mar. 10, 2002 article "PETA [People for the Ethical Treatment of Animals] launches 'Got Pus?' campaign," published on the Food Production Daily website:

“Somatic cells are white cells [leukocytes] that are present in both humans and cows, said David Reid, a dairy veterinarian in Hazel Green. While white blood cells are present in pus, they do not constitute pus in and of themselves. At proper levels, somatic cells prevent cows from getting mastitis, Reid said. High levels of somatic cells in milk indicate that a cow is sick and should not be milked until it is treated, he added.”

Mar. 10, 2002