The findings of this pilot study indicate that histone H3 deimination (CitH3) was strongly detected in almost all of the animal cancers assessed, pan-deimination detection as assessed by F95 reactivity was overall lower, and staining intensity of the five PAD isozymes varied between cancer types, with PAD2 and PAD3 being the most prominent isozymes across the specimens assessed. Here, PADI4 is linked to cancer.