When I was in veterinary private practice we used ethylene oxide to sterilize items that can't be steam sterilized. Might ask your vet if they'd be willing to sterilize it for you. Multiple items can be individually package and sterilized simultaneously. Just a thought...
Thank you for a great suggestion! I will check with our vet and see if they would be willing to gas sterilize my brush. If so, I will post pictures-it is a really nice brush with a long wooden handle.