הלכה על תמורה 57:34

The laws of the commandment: That which they, may their memory be blessed, said (Temurah 29a, see Mishneh Torah, Things Forbidden on the Altar 3:8) that the fee is that which he says to the woman, "Behold, this thing is to you for your wage." And it is one whether the prostitute is a gentile or a slave or an Israelite that is sexually forbidden to him, or from those that are prohibited by negative commandments. And so [too], the fee of a male is included in the fee of prostitute, but the fee of his wife when she is menstruant is not within the prohibition of the fee. And one who resolves with the prostitute to give her one lamb - if he gives her another, even if he does this with a thousand lambs, they are all forbidden as the fee (see Mishneh Torah, Things Forbidden on the Altar 3:11). And there is no prohibition of the fee and the price except with their bodies - therefore, the prohibition only applies to something that is fitting to offer on top of the altar (see Mishneh Torah, Things Forbidden on the Altar 3:14-15). And if one gives her a sanctified animal as a gift, it does not become forbidden, as the consecration already preceded and took possession of it. And what is the price of a dog? This is the one that says, "Behold, this lamb for that dog." And even if he gave him several lambs for one dog, they are all forbidden. And the remainder of its details are elucidated in the sixth chapter of Terumah (see Mishneh Torah, Things Forbidden on the Altar 1).