Neighbors dog got in my chickens

A dachshund.  Always hated those little sh**s.  This dingbat was
walking her dog and let him run off leash sniffing around my chicken
pen.  The thing found a loose spot under the wire and went in and
followed them right into the coop.  Mauled two of them.  A young
rooster got chewed up behind one wing.  His back looks kinda bloody. A
young hen was laying on her side, looking alert but unable to walk.
These are Rhode Island reds, about 5-6 weeks old.  Do I need to kill
the injured ones or can I give them awhile to see if they recover?

Hal