I suspect you'd have to have Digital Rights Management (DRM) applied to the PDF.
A PDF is just another file. Any file one has on the local machine can be transferred to another.
The issue is opening the file for its content.
Cann't say if the following is of any use to you; but, maybe worth a look-see.
Thansk for recommending breif guide to prevent opening file for its content. Well said we are unable to stop forwroding any file. The olnly way to protect PDF file is to make it secure or password protected but at the same time you con't stop, who is hell bent on copying your PDF.