This isn't normal.
Can he be wearing it off against something?
Otherwise I'd be worried it's some skin condition. Is it spreading?
Vets can be helpful
MACH3 Bretta Lee Wildhaus MXG MJG MXF MFB TQX HIT CGC TC
Glory B Wildhaus AX, AXJ, XF
"Behind every great man is a woman rolling her eyes." - Jim Carrey