Hello. Yes, you can use hot plate. Moreover, in this case hot plate appears more precise instrument, than Hagreaves's thermal test.

But how do you plan to use magnetic stirrer?

Thanks for your answer @Viacheslav Viatchenko-Karpinski, the instrument also has a magnetic stirrer function but will not be used

I think there is a little misunderstanding about hot plate.

This is the hot plate, which can be used for measuring heat-induced pain:

http://www.iitcinc.com/Product%20pages/Analgesia/Hotplate.html

I suppose you have a hot plate with magnetic stirrer, which is usual lab equipment for heating and mixing solutions:

https://www.amazon.com/Magnetic-Stirrer-with-Hot-Plate/dp/B007Y9DWSM

You cannot use this hot plate for measuring analgesia in rodents!