My seven year old lab,has a terrible itch under his chin,he scratches and rube it on the fire surround the floor,his claws,and he sometimes groans with the irritation as he scratches it,the vet has given him creams (hes had three tubes} but nothing seems to clear it up.Does any one have any ideas.
What kind of food and water dishes do you use? Plastic can cause those symptoms as small abrasions in it can trap bacteria. Stainless steel or ceramic might do the trick and you should wash them every day. If you already use them, try new ones. Make sure they are made in first world countries. Nickle content in steel can be a problem. Nothing came up on a culture? No mites, etc?
I'd check the food(I know bring up food here is almost like being a troll--since no one agrees about food). But our previous lab was horribly allergic to corn---constant itching that nothing the vet gave would stop. And the puppy is clearly allergic to it also. Recently we started giving him some popcorn from what we are eating, and suddenly he has this itch on his tail that won't go away. His current food has no corn, soy, or wheat. Just rice as a cereal. But you are sure its not the "seven year itch", right?