I question your MD a little bit. I'm not in Plastics, but I am in medicine. This sounds a bit like an MD who is imagining a risk "from snakes" without really realizing what the actual risk is. A breast implant is not placed shallow, even in the subglandular placement. Your snake would still have to puncture a fair amount of tissue layers to reach the implant itself. Your MD may, despite their best intentions, be imagining your snake puncturing 1"+ into your breast as opposed to the more likely millimeters.
Not that protecting yourself is a problem per se. A leather jacket or leather vest of even modest thickness should be enough to prevent most anything from puncturing deeply enough into your tissue to reach an implant.
But I suppose I don't know fully what kind of snakes you're managing. If you have something with 1-2" teeth, foam might be better than leather. Snake teeth are meant to puncture skin, and leather is skin. Heavy tanned leather might be sufficient, but I'd feel better with something that has sufficient thickness beyond the length of the teeth in question, hence the consideration for foam.