Pau D'Arco for cats?

Hi there, while picking up some Llysine at the Vitamin store the guy told me that this herb is also being used by rescue for cats.  It is supposed to help with their immune system, URI and even ring worm.  Re-searched online but couldn't confirm.  If it can be used, how much? Thank you.

I personally wouldn't use it unless it was under the supervision of a holistic vet. Herbs can be powerful stuff and affect cats in different ways than they do humans. It might be useful for treating a specific illness but I'd be less inclined to use it as a regular everyday supplement. If you want to boost immunity, a much better idea is to feed the healthiest, most species-appropriate diet you can (ie: not kibble).

I appreciate your input,