Sentry Natural Defense

Has anyone tried Sentry? I have been using K9 Advantix on Myrt and Frosty for a year.I dont like putting this stuff on them.Myrt's skin gets very sensitive after the K9 is put on.Her skin rolls when she is petted.
Myrt is still dealing with a bacillus cereus on her skin.
My Only Natural Pet catalog came today and they have the Sentry Natural Defense Squeeze On and the Castor & Pullux Herbal Flea Collar.
I do not like putting the K9 on them and Myrt's on going skin troubles makes me very uneasy.
 
The reason why a dog has so many friends  he wags his tail instead of his tongue