Dog. Many explain this in a figurative sense, as we have done in the last verse, to denote the public impudence by which some thought to honour their gods. (Haydock)

Such impiety the Lord abhors, though practiced by all the surrounding nations, as ancient records unanimously attest. How incredible soever it might otherwise appear, that a false notion of religion, joined to a natural depravity, could prompt people to such excesses, we cannot call in question the veracity of so many historians. See Herodotus i, and ii.; Just.[Justinian?], xviii. 6.; Eusebius, præp. iv. 6.; St. Augustine, City of God iv. 10; and the sacred writers, Baruch vi. 42., and Proverbs xix. 13. The Rabbins explain dog literally, and observe that a prostitute, or one who has had any commerce with a man with whom it was not lawful for her to marry, could not offer what she had thus gained to the Lord, nor what had been received in exchange for a dog. Josephus ([Antiquities?] iv. 8,) understands it of such hunting or shepherds’ dogs as had been lent for hire to propagate the breed. Maimonides thinks that what the strumpet had received in kind, could not be presented, but with the price of it she might buy suitable victims. But Josephus and Philo admit of no such exceptions. They reject all sorts of presents made by strumpets, in detestation of their crimes; and it was probably from the same motive that the Jews concluded it was unlawful to put the price of blood into the treasury of the temple, Matthew xxvii. 6. In the Christian Church, the offerings of public sinners were not received, even to be distributed among the poor. These would not even take an alms from the hands of St. Afra, while she remained a courtesan of Augsbourg. Even the pagan emperor, Severus, refused to admit into the sacred treasury the tribute arising from such unworthy means. (Lamprid.)

Some believe that Moses forbids the price of a dog to be presented, as the Egyptians had a sovereign respect for dogs; and many nations offered them in sacrifice, particularly for expiation. All the Greeks purified themselves, by making a dog be carried round them. (Bochart, p. 1, B. ii. 56.) Isaias (lxvi. 3,) seems to insinuate that dogs were sometimes immolated. St. Augustine, (q. 38,) and others, believe that dogs are not to be redeemed, as the first-born of other things are, probably because they were too mean, and the price too insignificant to purchase another victim. But we may adhere to the explication which was first proposed. (Calmet)

Both. The dog was an unclean animal, and strumpets defiled their own bodies, and draw down the indignation of that God, who is a pure Spirit, and loves chaste souls. Without are dogs and sorcerers, and unchaste, and murderers, and servers of idols. (Apocalypse xxii. 15.) (Haydock)