When I first got my gal, we had to take her temp often (navel ill). I bought an animal thermometer at the feed store, tied a string between the end of it and an alligator clip, inserted it in vaseline and stuck it in her anus. I then clipped the alligator clip above her tail head and waited. I've seen my vet spit on the end of the thermometer instead of using vaseline. I've had to take her temp as a much bigger animal (instead of calf size), but she is quite social with me. The clip and string allow me to get in in and keep it in and grab on something if she moves when I pull it out. It also allows it to not get lost if she poops (a guarantee) during the time its there. If your gal isn't so social, I'm sure its the same deal, just have her confined in a chute.