Sarcoptic Mange

Question
Two weeks ago, a stray Chocolate Lab wandered into our garage and made himself at home.  I think he just couldn't go any further, judging by the shape he was in.  He was diagnosed with sarcoptic mange and has had one ivermectin injection with the second scheduled for tomorrow.  How long will he need to be quarantined from our other dogs?  The vet recommended two injections, two weeks apart.  Do you think that's sufficient?  Also, will we need to treat the area of our yard where we're keeping him?  It is grass, plus concrete slab on a side porch.

Thanks in advance for your suggestions.  Want to be sure we get this resolved without an outbreak among the others.

Answer
Usually 2 shots of ivermectin are effective at killing the sarcoptic mites burrowed into the skin.  The mites do not live for very long off of the dog's body, so by the second shot, none of the mites can infect another dog from direct contact.  I would also recommend that the dog be dipped in either phosmet or amitraz to kill any surface mites that the ivermectin may have missed.