While you are brushing, carry a curry comb and clean off the brush alot. To give them a good cleaning, put them in a bucket with warm water, and some shampoo (horse works fine) and swish them around, if they are wood, dont let them soak 2 long. Then, just take them out and air dry.

I just shake all of the dust and hair out of the brushes and then soak them in warm soapy water for several minutes and then rinse them off after. Sometimes, if the hair is stuck deep in the brushes, I'll use a clean hoof pick to pry everything out, rinse it again in the soapy water and then rinse off with clean water.

Dusty hairy horse brushes bother me too, so I'm always cleaning mine.,

A bucket of warm water and tea tree oil (it's a disinfectant) works great.

Or just a bucket of warm water and some shampoo will do.

Rub the bristles of the brushes against eachother frequently during grooming. Knocks the hair and dust out.