What is the religious ruling on killing two dogs owned by one's father without his knowledge, and lying about the cause of their death to get rid of the harm they cause?

If dogs are harmful and their harm cannot be averted except by killing them, then it is permissible to kill them, provided that no greater harm results from doing so. If killing them would harm the father, then they can be disposed of secretly, and one can use equivocation or other means to avoid lying. However, if compelled to lie to avert harm or achieve a legitimate benefit that cannot be attained otherwise, then lying is permissible in such a case.