I wasn't aware of any aversion to western medicine on the part of zen buddhist. I know other forms of "buddhism" have medical traditions that involve using the dharma to promote healing but Im not aware that they resist modern medicine. TIbetan buddhist certainly do not, the lamas own brother has seen psychiatrist in a professional context.
I could see argument being made based on the use of animals in medical research but by the same logic this would precluding them from enjoying most modern technology as someone or something has suffered in the process which led to the technology.
From the four noble truths,
Know the sickness,
Abandon the cause of the sickness,
Aspire the cure and
Rely upon the medical treatment
Gautama buddha spoke using medicine in analogies sometimes and I feel this confuses some people on the topic. He was saying that the dharma can be looked at like a medicine and Sangha as doctors. He was making an analogy of spiritual healing in terms of medical healing. He also did discuss that medical healing has psychological components for the patent but never says that doctors have to be able to address both aspects, rather the patent must be aware of accepting their disease and embracing the medical treatment as also curative for the nonphysical aspects of the disease (although this maybe indirect often)
In tibetan buddhism (and others to a lesser degree) the sciences are expected to be pursued by those wishing to become enlightened,
The science of medicine
The science of logic
The science of language
The science of art
The inner science of mental training
Medicine as we think of it (western) was actually fairly advanced in terms of surgeries and such because of this thinking, before western contact.
