All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger. We ask Allaah to exalt his mention as well as that of his family and all his companions.
The Prophet said: ''The purity of a receptacle of yours which was licked by a dog is to wash it (that receptacle) seven times, the first of which with soil.'' [Al-Bukhari and Muslim].
Therefore, it is an obligation to wash a receptacle which was licked by a dog as it became impure by the lick of the dog, and the food or drink which it contained should be spilled away.
However, if the dog drinks from running water or from a large quantity of water, then this does not make it impure.
Allaah Knows best.