His wounds look pretty deep, but chickens can recover from some awful injuries. He may be in shock for awhile, and sometimes chickens will die from that. When he is stable enough, clean his wounds with weak Betadine, Hibiclens, or soap and water. Normal saline is also good, but put some antibacterial soap in with it. Let it dry off, then apply some Neosporin or other antibiotic ointment. Getting him to eat, drink, and to not get infected will be the next hurdle. Offer him eggs, tuna, dry cat food, or other high protein items in addition to his feed to tempt him to eat. An antibiotic such as amoxicillin. keflex, or clavamox would be good if you can get it. Keep us posted. Good luck.