Sentinel is Interceptor with Program added to break down the outer layer of the fleas eggs so they won't hatch.I would think that the safest way to go with an allergy issue would be Ivomec.Frontline is safe,but seems as of late to be less affective.Have you tried Vectra for ticks(fleas also)?Safeguard is a great addition to your regimen too.Hope you find the right combo for your dog,allergies can be a real "bugger".
