Is it harmful if dogs eat an egg everyday?

No, unless your dog has a specific medical condition. For example, a raw egg each day may not suit an elderly dog who cannot digest raw as easily.

Eggs are a great form of easily digestible protein, but they do contain fat as well.

I have dogs in my canine food therapy practice where an egg a day has been too much for them. It is so digestible that they have quickly gained weight and then the owners have had to adjust their diet.