More Calf Doctoring

I'm back with more calf doctoring information. Kerstin asked a question on the last calf doctoring post, which was: Do you use a new needle for every shot you give/every calve? I couldn't find your email address Kerstin, but very much appreciate your question, and am happy to answer it.
No, we don't switch needles every time we give a cow/calf/yearling a shot on our operation. Some people do. However, the odds of transfering anything but a blood disease is extremely low (I have never witnessed anything transfered animal to animal from a needle in 25 years), and the cost and time associated with changing needles after every animal is uneconomical. Now, if there was an actual concern that we may cause a health related issue through using needles on more than one animal, we would absolutely change them after each shot. The animal's health comes first, and there isn't a concern in that area with most of the shots we administer, so at that point we look at cost and time associated with a practice, and that's why we choose not to switch with every animal.
We do switch needles every few head. This is because the needle will become dull, and can get dirty, bent etc..., and we are very consciencious of anything that can impact our animal's health, like manure, dirt, a needle that may break, or a dull needle that makes it more difficult to administer a shot.
Switching needles every few head is also the way every vet we use prefers to administer shots.
Specifically with doctoring calves, and giving them LA200, I typically switch needles every day. That would encompass 1-5 head given shots with the same needle.
Thank you again for your question!