לֹֽא־תָבִיא֩ אֶתְנַ֨ן זוֹנָ֜ה וּמְחִ֣יר כֶּ֗לֶב בֵּ֛ית ה אֱלֹ-הֶ֖-יךָ (Devarim 23:19)
Why a dog that was exchanged for a lamb is not allowed to be brought as an offering? Why are dogs singled out here?
Mi Yodeya is a question and answer site for those who base their lives on Jewish law and tradition and anyone interested in learning more. It only takes a minute to sign up.Sign up to join this community
It is a sheep who was traded against a dog that is forbidden to be brought as an offering. See the gemara in Temura 30a and following. Such a sheep is forbidden as the verse continues: as it is "abhorrent to the LORD your God.
Regarding dogs specifically artscroll, quoting Ramban, explains
Dogs are considered abominations because they were often trained to be vicious and this became a menace to the public. It is common for sinners to try to legitimate the profits of their activities by contributing to charitable causes. By forbidding the use as offerings of animals given in exchange for harlotry or for dogs, the Torah symbolizes that ill-gotten gains cannot be cleansed by using them for holy ends; God regards such a practice as an abomination.
Beyond the general prohibition of exchanging animals for sacrifice (the topic of the tractate of Temura based on Vayikra 27:10), there are other animals which are also prohibited as sacrifices, e.g., a cow that gores and kills a Jew and its offspring (Temura 30b).