Is too much bad for you? Maybe, if you stop eating because you're so focused on fucking you lose interest in food. You're a human and have a WAY broader life than any dog ever has, and there are a lot of areas where you can fall off in pursuit of orgasms, not really all that many for a dog is there? If the dog stops eating because he's fucking too often, I'd worry. Other than that, it's not even worth thinking about.