Human thermometers are used to take a dog's temperature. This is done rectally. A normal temperature for a dog is 99.5 to 102.5 degrees Fahrenheit.
As long as you know how and what your looking for. We don't take an oral temperature on dogs. I would mark it with a permanent magic marker too (Sharpie). I have an H thermometer and a D thermometer marked on the thermometer and the case so there's no confusion, lol. Make sure you disinfect properly as well before and after each use. ;-)
Well I'm not really a vet so I don't really know if you can use a human thermometers on dogs, but why don't you just try man!?