Hi there,
Is he neutered?
What does he eat?
Does he get some sun every day?
Thanks,
Terri
Dear jlee,
In a three year old dog that is eating well, I do not think this is a serious issue.
Most neutered dogs do develope dark pigment in their fur, eventually. So your other boy will most likely darken as well.
You can give them a daily vitamin with Omega 3 fatty acids to promote great coat color.
They can also have melatonin:
http://www.petplace.com/drug-library/melatonin-melatonex/page1.aspx
Please let me know how they are doing. I LOVE Pugs. They are wonderful!!
Warmest best wishes,
Healthcare Expert
Expert in canine health and behavior. 20 years of experience with dogs