Someone told me that you should feed only the yolk of a raw egg, because the white is hard to digest. Other people say throw in the whole eggs, shell and all. Is there any truth to the white being hard to digest?
The reason that some people recommend you only feed the egg yolks, or that you should only feed boiled eggs (and never raw) is because egg whites contain a protein called avidin.
Avidin binds to biotin, and if you were to feed your dog only raw egg whites, it would create a biotin deficiency. Fortunately for us, egg yolks continue plenty of biotin, so if we feed whole raw eggs, there really isn't anything to worry about.
You can feed eggs raw and whole, including the egg shells, if your dog will eat them. Abby didn't used to like the shells, but Ronja doesn't mind them. It comes down to personal preference. I've never had any tummy issues due to shells, personally.
The only issue i'd have with feeding the shell is the whole calcium issue with puppies. If your puppy is getting calcium through it's kibble, there's no need for that extra calcium from egg shells. Too much calcium isn't good for a growing large breed puppy. With adults, it (the shell) shouldn't be an issue.