Biting horse

[Ransa]

Hi!
I am currently loaning a gelding at least 13 years old. My problem is that he tries to bite nearly everyone that opens his door, although he absolutely loved his last loan! He has good days and bad days but on his bad days he definitely tries to bite.
I would love to stop him biting, any ideas?

 

[Cortez]

Carry a stick and use it.

 

[Ransa]

Yeah, that would probably work thnx but I would personally use it as a last resort as I want him to trust me.
Thanks for the idea