Don’t assume stretching is always good for your horse or dog! Depends on how it’s done, when it’s done, and how often, just to name a few obvious factors. (And yes, there are potential benefits to stretching, just some potential pitfalls as well.) In my books I teach a good alternative to stretching for the limbs, which is to use a combination of jostles and circles to help muscles relax and stimulate joint fluid.
I also believe that massage provides a much more efficient and effective way to improve range of motion. It can melt adhesions that may be restricting joint movements, and can also help get other releases in the connective tissue. Theoretically this is what stretching does also (one of the benefits), but only if the stretches are held for a length of time. (Some say at least 90 seconds for this to happen. Try telling your horse or dog that as you’re trying to hold their leg in a stretch!)