Is it considered a sin not to allow a domestic cat to mate with its own kind?

As long as you did not prevent the cat from eating and drinking, there is no sin upon you for not enabling it to mate with its own kind. This is because sin was mentioned for those who imprisoned it and withheld food from it. However, if preventing it [from mating] is intended to cut off its offspring without a valid benefit or to avert harm, then it is not permissible.