Quote:
>
> say that I have this example:
>
> /path1/horse/any_path
> /path1/dog/any_path
> ...
>
> I need to rewrite ANY URL that does NOT
> include "horse" as second path component.

putting this condition before your rewrite rule should do the trick
RewriteCond %{REQUEST_URI} !^/[^/]+/horse/