Neutered Male Dog Trying To Mate

I currently have 2 dogs. The younger one is neutered. The older one which we just picked up is not neutered and is constantly trying to mate my younger female dog. This old dog always ends up being badly bitten up. I understand that the older dog cannot be neutered and, on top of that, this old dog has a heart problem (heart murmur). Is there any other ways to resolve the problem? Please help me. (Jeffrey - Singapore)

This is an age old problem with no easy answer. It is unusual for your dog to be so persistent, for the following reasons in particular: a) He is being told-off very severely every time he tries; b) He is old and may not have the stamina or desire as younger dogs; c) if your female is neutered she should not be so attractive to males. The first thing I would do is make sure that your dog really is neutered. If she really is, then I can suggest nothing other than to separate the dogs when you are not present to stop him from 'misbehaving'!