My Pony Got A Puncture Wound!

Last night, I had my Shetland pony, Pete, in the barn, picking out his feet. My barn is old, but I had gone through it and tried to make it as "horse-proof" as possible. Well, apparently, I missed a freaking nail, and, of course, Pete found it and stabbed himself on it! Arrgghhh!!!

A rusty, old nail stabbed him on his off-side hind foot, right on his heel, where the coronary band meets the hoof.

It went in almost 1/2 an inch! I freaked out, knowing the risks of a puncture wound in a horse! Tetanus, lock jaw, infection, abscesses! Yikes! Pete had his Equine 5-way shot back in April, with a Tetanus antitoxin, so that was relief, but what else should I do? Does he need a booster? I called Fair Grove Vet this morning, who I use for my horses, and they were most helpful, as usual.
They recommended I give Pete a Tetanus Booster shot (thankfully, it is an inter muscular shot, as I am not comfortable giving IV shots.) They also told me to start him on a round of Penicillin, 20 mm a day for 4 or 5 days (also an IM shot, thankfully!) Also, I am to buy a Betadine/Iodine soak and soak his little foot for 4-5 days. Poor Petey, he will be super mad!

Peter is really not the best little patient, as he has no patience. I just hope I can avoid an abscess or an infection. He lives out on pasture 24/7, so I really worry about him. Poor little guy!
As an update, he did loose all 4 of his front teeth, (milk teeth), his gums are heeled and look much better. I joke that Peter is getting his man teeth!