I don't believe being in heat impacts a dog's instinct to want to hunt; only the attention span of the male dogs. Years ago we made the mistake of loading a [censored] in heat as we gathered our beagle pack, discovering our mistake upon arriving at our hunting destination. This [censored] was our best dog, and needless to say with the male dogs going crazy, we were convinced our hunt was over. Not knowing what to do I began rambling around in the glove box of the truck looking for inspiration when I found a bottle of Vicks Vapo-Rub; and subsequently, experienced a bit of divine revelation. I smeared a big glob of Vapo-Rub on the hind end of that dog and turned her loose. She was immediately swarmed by the males; but when those dogs got a good whiff of Vapo-Rub up their snouts, they wanted absolutely nothing else to do with this [censored]! The result was a great rabbit hunt with some of the best races (beagle music) we'd enjoyed all season. I've not experienced this problem since; but if I were to so, I'd try that Vick's remedy again in a heart beat.