If I barely tug on or touch my dog's whiskers they come right out!
This might be due to bacterial or fungal infection. Some autoimmune diseases might also cause this.
However dogs shed their whiskers like the rest of their fur and grow them back it. It might be your dog is just at the point of losing his whiskers.
If it seems like more than that you should see your vet to check for skin problems in the whisker area.
Hope this helps you!