What is the ruling on selling food and supplies for cats and dogs?

The default ruling regarding selling food for cats and dogs is permissibility, unless it contains something forbidden, such as pork or carrion. The fact that some people keep dogs in a forbidden manner does not mean that feeding them or selling their food is prohibited; for Islamic law encourages kindness to animals. Therefore, there is no objection to selling animal food and supplies. The sin of keeping a dog remains with its owner if the keeping is for reasons not permitted by Islamic law. The buyer can be advised if it is strongly suspected that he is keeping the dog without need, and it is preferable to look for another project that is further removed from doubts.