Is it forbidden for a veterinarian to charge a fee for treating a dog or a cat, by analogy with the prohibition of their sale price?

"Treating the aforementioned animals is permissible and falls under showing kindness to creatures. It is narrated in the Hadith: 'There is a reward for every wet liver.' And also: 'Those who show mercy will be shown mercy by the Most Merciful. Show mercy to those on earth, and the One in the heavens will show mercy to you.'

Since treating animals is permissible, there is no objection to taking a fee for it. This is not analogous to selling the animal itself, as the fee is for the treatment, not for the animal itself or its benefits.

However, if the work of the veterinarian leads to the acquisition of animals that are not permitted to be kept, then his work is not permissible from that aspect."