وَسُؤْرُ الْكَلْبِ وَالْخِنْزِيرِ وَسِبَاعِ الْبَهَائِمِ نَجِسٌ
Translation: The leftover water of a dog, pig, and predatory beasts is impure.
This includes dogs, pigs and predatory land animals. In Hanafi law their saliva renders the remaining water impure.
The proof relating to dogs, and Malik's differing view, clarify how jurists reason about the ruling.