You really need to stay out of the cold.
That said, try an Athletic store or some place that sells hunting equipment. They also make warming socks with batteries - I don't think they have an on and off switch, but I could be wrong.
The Disabilities Act in the Us would certainly protect your job, somewhat. They could move you to another position, but they couldn't fire you.
Skin kids - Jason, Kevin, Allison
Canine kids - Bennett & Bailey (always in our hearts), Riley, Banker, Rogue and Boz
Feline kids - Zoey, Talley and Abra