Believe it or not, despite extensive education and scientific training, veterinarians can be quite superstitious. These superstitions are not your typical ones but are specific to the profession. And for whatever reason, many of them relate to blood collection and catheter placement.
One of the biggest no-nos is to say how easy something will be. "Look how big that vein is! That'll be a cinch to hit!" Comments like this are certain to result in the opposite outcome. If you state that a catheter will be easy to put in you'll inevitably miss, blow the vein, or otherwise have to stick multiple times. The same thing happens with blood collection. Ironically, if you say it's going to be difficult it often is. So the best thing to do is to keep quiet and not make any comments at all. You can go into any veterinary clinic, say "this will be quick and easy" and hear the entire staff groan because they know how hard you just made it. Also, if there are several difficult venipunctures you will hear people talk about needing to appease the "catheter gods", and they're likely only half-joking.
Another truth is that the busier your schedule is the more likely you are to run into difficulties with routine surgeries. Your suture will slip, you'll have a hard time finding the uterus, you'll have anatomical abnormalities, or just about anything else that doubles the length of the procedure and sets you back. When you're slow the surgeries will be fast and you'll get finished and have nothing much left to do.
You also quickly learn that the nice, sweet pets will develop serious or fatal illnesses while the cranky, mean ones will continue to survive with congestive heart failure or cancer even without treatment. It's not fair, and it probably isn't even statistically correct, but it sure feels like it. Along the same lines, it will be the worst behaved patients that will need to have blood collected a second time or have multiple repeated x-rays because the first ones didn't turn out right. Basically it's all Murphy's Law in action but specified for the veterinary profession.
To paraphrase Bruce Wayne as he decided to become Batman, "Veterinarians are a superstitious lot." I would be interested to hear from my readers all of the superstitions and quirks along these lines that you have seen or have at your own practice. I know there are plenty more out there, and I'd love to hear about them!