Is buying and selling dogs permissible?

Opinion of the majority of jurists
The majority of jurists maintained that selling dogs is impermissible. They based their opinion on the hadith (prophetic tradition) reported by Abu Mas'oud al-Ansari (may Allah be pleased with him) who narrated that the Messenger of Allah (peace and blessings be upon him and his family) prohibited taking the price of a dog, the earnings of a prostitute and soothsayer. Jurists stated that from among the conditions of the sale contract is that sold item must be pure. They have agreed that dogs are filthy (najis).
To facilitate the matter, in shari'ah (Islamic law), owning or exchanging a dog for any lawful purpose must not be through a buying and selling transaction but through relinquishing control of the object i.e. the person who has the dog relinquishes his control over it to someone else in return for a monetary compensation. In this case, the money is not deemed a price for the dog but for its relinquishment.
This is not a sham deal; it is different from a sale in that as soon as the person who relinquishes his control over an article receives the money, he is not obliged to guarantee the relinquished article, even its deliverability. In a sale, on the other hand, the seller guarantees the sold article until the buyer takes possession of it
The luminary and Shafi’i scholar, Al-Qalyubi wrote in his meta-commentary on Sharh Al-Jalal AL-Muhalla (2/383), “It is valid to agree on a benefit such as that derived from a dog or dung; the money exchanged is in return for relinquishing control of the article and not in return for the benefit or the article’s possession.”
Opinion of the Hanafi jurists and others
The Hanafi jurists and others who maintained the same opinion have permitted selling dogs which are kept for lawful purposes (eg. hunting, guarding etc…). They based their opinion on the hadith reported by Jabir Ibn Abduallah (may Allah be pleased with them both) in which he said, "The Messenger of Allah (pbuh) prohibited taking a price for selling dogs except for those kept for hunting" [recorded by Al-Nisa`i]. Therefore, there is problem in trading or selling dogs for lawful purposes.
Ruling
It is lawful (halal) and there is no objection in the shari'ah (Islamic law) to trade in dogs kept for hunting or any other lawful purposes (guarding etc..). This permissibility is based on the opinion of Imam Abu Hanifah or on paying money in return for relinquishing control of the dog according to the opinion maintained by the majority of scholars.