Here is some information on eggs from my holistic vet:
“The diet of chicken’s is key to the superior fatty acid profiles in omega-3 eggs. For high omega-3 eggs, chickens are fed flax. Chickens are able to convert the oils in flax into more usable forms of fatty acids better than a dog or cat can. For high DHA eggs, chickens are fed flax and algae, with the same good results. Better food, better chicken, better eggs! High omega-3 eggs, such as Eggland’s Best, have good fatty acid profiles and good levels of vitamin E. It’s also a good choice if you are able to buy eggs that are locally raised. You may feed raw or cook the eggs lightly (if you wish) but keep the yolk intact and uncooked to protect the fragile fatty acids from exposure to air and heat. Some dogs don’t digest raw eggs well but do fine with them cooked. If you are concerned that raw egg whites may interfere with biotin absorption, cook eggs slightly (refer to above) so that the whites are cooked.”
Eggs, provide Vitamin A, Riboflavin, Folate, Vitamin B12, Iron, Selenium along with the Fatty Acids mentioned above.
Eggs should not be the mainstay of your dogs’ diet but it’s great to feed eggs a few times per week. Feed amounts should be cut back appropriately depending on how many eggs are fed.
If using the shells for a calcium source, it must be ground up to a fine powder to allow the dogs to absorb them. A “Bone Meal” supplement would be a better choice, unless you are feeding a diet with boney meats, as it has the proper calcium and phosphorus balance. Regular “calcium” supplements that do not have phosphorus are not appropriate. Bone meal should be Human edible, made in a USDA plant and be certified that’s it has been tested for heavy metals and other contaminants. That being said, you should not feed eggs shells if your dogs’ diet already includes a calcium supplement as it would be more than what your dog needs. Too much calcium may be harmful to large breed puppies. They can also bind to other minerals making them less available to your dog.
Hope this helps!