Brigham tea is quite good.
This formula also is good (it has Brigham tea in it too).
https://homegrownherbalist.net/collections/respiratory-formulas/products/histamine-support
The problem with dogs with allergies is that they’re sometimes allergic to the herbs too so don’t get any benefit.
Humans respond more reliably.
Doc
Don't use herbs or combine herbs with medications or use them during lactation or pregnancy without talking with your healthcare provider.