Yeah, if you are pretty certain the cat is killing and the quarry is fresh, the biggest risk is internal parasites. Symptoms: diarrhea, vomiting, lethargy, weight loss.
Ahh... they are always so proud about the whole thing. At least Jangles is killing. I used to have a cat that brought her quarry in live and put it my deep soaking bathtub for fun and games and then leave it there for it to freak me out. I swear cats love doing that kind of thing... freaking others out. Sociopaths!
Dutch Shepherd - Ptygo (Tee-Go) de las Flores
Rescue GSD - Freyja (Husband's Dog)