Thanks for the prompt reply.
1. Collar removed last night
2. no itching or scratching
3. brown spots did not come off
4. brown spots are flat, not built up; look like normal spots on skin, but restricted to area of hair loss under collar.
Other: Hair loss only on bottom of neck
Thanks for all the prompt responses. I am traveling today for 2 weeks; hence the urgency. I will be back on May 30. Hopefully the hair will start growing back by then. He has had other issues with rubbing and hair loss, particularly under his harness in his armpit (he is a working Husky, or sorts), but not the same brown spots.