Misha attacked another dog (aDork)

spiritdogs

You also have to consider that some dogs, as they reach social maturity, are more prone to guard their human and their property, and less prone to want to play with other dogs any more. 

 This is exactly what I was thinking. If Misha really is a mix of the breeds listed (Pyr/Chow/Aussie), it would be fairly predictable that he would reach a point where making doggy friends with intruders was no longer something he was interested in. 

aDorkable

Misha's bloodwork came back normal

Give some scritches to Misha for me!

Yes, Johnny, his thyroid was checked. :) The vet told me I was on the right path to get it checked out.

Thanks,  tiffy! I'm glad everything's okay too.

Agile and spiritdogs -- exactly along the lines of what I was thinking. I figure careful attention during training, and slow reintroduction will tell me if he's still interested in making friends just not on his property. I'm not against making changes to his routine or mine. If he's at a point where he wants to guard "his" property and not welcome other dogs or people, we'll take precautions to make sure he and passers-by are safe and secure. Having him well-trained will help with this.