Honestly is not as hard as it might appear to you right now. I have a few Chiro friends and first met one while visiting then through one met a few more... What I've learned is that most practices are small and thus operate very quickly.. They can make decisions on the spot if they like something or remove a system of they don't... Same as hiring their staff...
Call for an appointment and simply let the receptionist know you're bringing in a product to help their office... All doctor visits have a first time meeting anyway.. So getting to chat with you about a product (specially if is actually helpful) might give them a joyful break in their day... Go with a solution and maybe some sort of trial for them to experience it then is just a matter of not necessarily closing them but retaining them through that much smoother "close" via trial...
There's nothing better in a pitch than a free goodie... Also, try having your pitch incorporate an existing user that might be a competitor.. No one wants to be the first but no one wants to be last either so play that in your favor...