Is that true for every type and format

Yes, OTC for everything. I've heard that some pharmacists ask more questions about types which are commonly abused by body builders but that's about the extent of it.

Funny story since you mention cats: My brother's cat was diabetic and prescribed long acting insulin which cost $250/vial. I looked it up and... apparently it was just relabeled lantus, because of course nobody is going to waste money on a separate manufacturing line. Ended up buying it from my local pharmacy, without a prescription, instead of using the vet prescription.