Discolored spot with fuzzy borders on testicle

My 4 year old deer  Chihuahua has a discolored spot with fuzzy borders on his testicles. It doesn't look or feel like a raised bump and it's hard to discern as much. I've taken photos, does anyone have any anecdotal or professional input that would help me in deciding if I should have him seen?

Hello and I agree with you that a change in skin colour is potentially significant and ought to be checked by a vet.  I thought about skin diseases such as Ringworm (wash your hands very well afterwards and perhaps encourage your boy to avoid immunocompromised people until this has been ruled out), tissue change such as cancer or things like endocrine disease.

Please will you let us know how you get on?