Mischna zu Hoschea 13:78

If one lowered wheels or the gear of oxen into water at the time of the hot east wind in order that they might become tightened, this comes under the law of ‘if water be put’. If one took down a beast to drink, the water which came up on its mouth comes under the law of ‘if water be put’, but that which came up on its feet does not come under the law of ‘if water be put’. If he intended that its feet should be washed, even the water that came up on its feet comes under the law of ‘if water be put’. At the time of footsoreness or of threshing it always causes susceptibility to uncleanness. If a deaf-mute, an imbecile or a minor took it down, even though his intention was that its feet should be washed, it does not come under the law of ‘if water be put’, because with these the act alone counts, but not the intention.