To my humble knowledge, most people are prescribed pills, and some of the animal stuff comes as a cream in a tube, so the preparation standards are likely different. Now, the actual formulation is the same, but the preparation and most importantly, the dosages, are different.
The MOST important thing is that if you advocate that folks go get the animal med when the authorities block the human form, you're guaranteeing that some are not going to be able to calculate the percentages correctly, and harm themselves, so I wouldn't advocate that, unless it was in the MOST extreme emergencies, after it has proven to be a miracle cure etc. It's just too risky, so IMHO, I tell people that if the doctors, pharmacies, insurance companies, and other leading authorities block it, you're just out of luck.