What are the receptors for changes in temperature within the skin?

In humans, temperature sensation enters the spinal cord along the axons of Lissauer's tract that synapse on second order neurons in grey matter of the dorsal horn, one or two vertebral levels up. The axons of these second order neurons then decussate, joining the spinothalamic tract as they ascend to neurons in the ventral posterolateral nucleus of the thalamus.  So the receptors that do this is the thermoreceptor.  

Pe.dometer would be the most useful to you for monitoring heart rate.

As long as it was one lick and the dog is a bigger dog, it should be fine. watch it carefully for a few days.