Is it permissible to perform a surgical operation on a guard dog to prevent reproduction, for fear of their multiplication and out of mercy from getting rid of them?

It is not permissible to perform a sterilization operation on an animal merely for sport or to torture the animal without a significant benefit or to ward off an unusual harm, as it involves altering Allah's creation. Regarding dogs, scholars have differed on the ruling concerning killing them. Some have permitted killing all of them, while others have seen the command to kill them as abrogated. The purpose of forbidding their killing is the fear of their eradication. Therefore, it is not advisable to sterilize dogs if it is for no significant benefit, because it is akin to eradication. However, if there is a benefit, then there is no objection to it, just as it is permissible to castrate other animals for a benefit. As for the fear of reproduction, it is not considered a benefit, and performing the operation for this reason is considered torture to the animal, hence it is not permissible.