I'm not sure about the prescription laws in you area, but in mine it's against the law for a veterinarian to prescribe a medication for an animal they have not examined themselves, or at least gotten a prescription sent from a veterinarian who has examined the animal. There are no species exception to this rule, as far as I aware. There must be a client-patient-doctor relationship before prescription medications can be given out. In fact, if you vet gives out meds without seeing the pet, they are risking their medical license and could be suspended and/or fined and/or officially reprimanded by their governing body.

I'm a veterinary assistant at a clinic that specializes in exotics. It always amazes me when people we've never worked with before phone us up wanting "the dewormer" (or whatever) for their reptiles without us seeing their pet, or even just doing a fecal! Not that I'm saying that's what you did- we just come across it a lot! It's really nice when someone will work with our vet, and do the proper diagnostics (fecals, x-rays, washes, swabs, scrapings, whatever) to make sure that the treatments we send home are ones that are dealing with the true problem.