Egg yolks contain about three times the amount of omega-6 to omega-3, so I have always said if you are going to give eggs, give three egg
whites to one
egg yolk, so the balance becomes stable and beneficial.
Egg whites have (obviously) far more omega-3, but they are also high in cholesterol, so feeding too much is not good for a dog's heart or cirulatory system.
A much better source of omega-3 is salmon oil, as this has many beneficial properties and is easy to digest.