Like others, my RV is nice in that it has a driver control to activate a fan under the kitchen table that blows air through a heat exchanger that has engine coolant running through it. So we get engine-generated heat in the house. And it is HOT. Hot enough that the kids will complain to me to turn it down as it is burning their legs under the table. :)
My RV also runs coolant through my water heater (it's called "motor aid") so I get hot water for free from the engine also.
But honestly, I don't think I'd worry about dogs too much. Put down some doggy beds and they have fur coats and they will be fine. If you're running the heat up front in the cab I doubt it's going to get much below 40 in the house.
As has been said, you can either run your generator for 120VAC heat, or you can run your furnace.
Another option are 12VDC heaters. Gotta be careful about blowing fuses though.
https://www.google.com/?gws_rd=ssl#q=12V+auto+heater
Steve