Sayyiduna Adi bin Hatim (may Allah be pleased with him) says: I asked the Messenger of Allah (peace and blessings be upon him) about game caught by a dog, and he (peace and blessings be upon him) said: "Eat what it holds for you, for its catching it is its slaughter. If you find another dog or dogs with your hunting dog, then do not eat; you said 'Bismillah wallahu akbar' (In the name of Allah, and Allah is the Greatest) when sending your hunting dog, while it was not said when the other dogs were sent."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصيد والذبائح / 18870