Just dropping in with a progress report.

Today is day 42...
We are continuing to slowly, steadily make progress. The big moment of the past couple of weeks has been a willingness to walk. His bolting around the house has gradually gone from bolting around (crashing into walls, knocking over furniture, falling down, just bolting in a blind panic) to darting around (running, and scared, but not crashing into things as much - more in control) to...kind of briskly trotting around. Now he will occasionally just pause in his trotting and look around with alert ears. The slightest move from a human will have him bolting back under there, but - progress.
The other big thing also concerns what started as his bolting-around-the-house behavior. About a week ago, my husband was at his desk and our boy (who I think it won't hurt anything to say, since I haven't named the rescue, we're calling him Hobbit) was underneath it. I was scooping food from the food bin to feed Violet and Mavis, and he ran out from under the desk, circled the house, and back. I felt bad because I felt like I'd startled him with the sound of the food hitting the stainless steel bowl, so I tried to be a little quieter. Then he did it again - and my husband said, "Honey, I think he's excited because he thinks it's his dinnertime." I was skeptical. He ran around again, but I thought he was still just spooked.
The next day, I was clanging around in the kitchen, same distance from him as the dog food bin, and he was under the desk again. My husband was at his desk again. I was banging around, making lots of noise - and he didn't spook. A few hours later, I started to feed the girls, and he did it again.
He's done it every night since. He
is excited about dinner.
Around the same day, he was running out from under the desk and toward the back door a few times. I was doubtful that he could need to go outside, because that level of communication would have been completely unprecedented, and it wasn't a time that he normally went out anyway. Well, he pooped on the floor. It was his very first accident, and I was elated. He told me! It wasn't even just that he got the concept that outside is where we potty, it was that he had a need, and communicating to me that he had it was less daunting of a prospect than just holding it. Oh, man I was happy. It wasn't a fluke, either. He's "asked" to go several times since, and once more I didn't respond fast enough, and he peed. I've never been so happy to have my floor peed on.
A few days ago, I brushed him for the first time. He's looked like heck since he came, not in a matted and uncomfortable way, just oily and unbrushed. I held out for a long time, because it wasn't worth it to risk traumatizing him for aesthetics, but finally I felt like he was stable enough for a light brushing. He actually seemed to like it. He was fairly relaxed for it.
Yesterday, I spied him sleeping under the desk - on his back, feet up in the air.
So, that's where we are. Not a bad place.
