Hi I'm making a fanfic and I was thinking how advance Equestria is on the field of medicine.

How do they call the ambulance if somepony gets injured?
Can non unicorns be surgeon ?(I'm not sure if hooves are that good in surgery and using thier mouth might make the instrument contamintaed.)

4180292
To call the ambulance, they probably either yell for help, the unicorns send up a flare with their magic (maybe), or run/fly to find someone to help. Or dragon-fire mail.

Since ponies can apparently pick stuff up with their hooves, like a rock or other object, they can probably hold scalpels too. Also, wings, hooves, tails, and horns are appendages that can grab stuff. The surgical profession might be skewed towards unicorns, as they can hold multiple objects at once in their magic. Other medical specialties are probably more evenly filled up.

4180292 Well, we do know that they have X-ray machines, so other tech is a reasonable consideration.

4180292 Some/certain Earth Ponies are very good at manouvering their tails and even Manes.

Pinkie Pie ould be a mean Surgeon, if she had the urge and there was the need.

The fac that she can hold on to things with even her mane, aside from tail and hooves, and at extended distances?

She may be a special case, but still.
4180548 Oh yeah, that Cider, Yay.
4180870 Some good Unicorns could be x-ray machiens ..

4180548
Since G4 Equestria has quite a bit more species, the surgical profession is probably not so unicorn-dominated now, and has more hippogriffs and griffons and dragons who can hold stuff in their hand-like claws, and changelings who have the same horn manipulation as unicorns.
That does leave yaks out, so I wonder how medical care is in Yakyakistan...