Did you know that we STILL don't know the cause of headaches? Doctors are baffled! Hmm ... over the right eye ... does your husband work on a computer?

Maybe taking breaks and doing eye exercises would help. 1-2 minutes every couple of hours might help... but I've not yet heard of animal allergens causing headaches.

Any stress in his life?

Headaches are something that a lot of people deal with, and it has a lot to do with what we expose ourselves to. I did research on air quality because I was having a hard time in my home with a lot of junk and smells, so I consequently found that headaches can actually be cause by bad air. It makes a lot of sense that your husband has this problem with your dog being in the office all day. The problem mostly comes from the fact that the air in his office probably isn't being properly replaced with fresh air. Spending a long time with a pet in the room, without fresh air coming in, can easily make for problems.

What I would suggest is getting either a whole house filter, or simply a single-room purifier unit for specifically his office. I actually have a room purifier in my own room, just because sometimes a strange smell comes back from the previous people who lived here. It has really helped me out, and I found that being in my room has been easier on my own system.

I agree with the theory that air quality and environment influence the quality of blood circulation in the body. Without oxygen, we simply shut down. Quick inhalations and exhalations aka "breath of fire" does wonders to wake up the system and refresh the flow of oxygen to the brain.