I work at a pet boarding facility and we have the same policy. There had been times that the owner would pick up their pet and ask to make payments on it, or pay it on by a certain date. Doing that there were times we didn't get our money. Our policy now is that we have to be paid in full before the pet is returned to it's owner. The difference is most people plan in advance to bring their pets to us, unlike a vet's office that has a lot of emergencies. My avian vet doesn't even accept checks because it's such a hassle for them if they bounce. I've had to deal with that too, believe me it's a pain.