We on occassion will add to their kibble or use as a treat some of these:
- veggies - raw or cooked: peas, carrots, string beans, squash, broccoli, cooked sweet or white potato (leave skins on), sweet pepper (any color), spinach. We add just a spoon or two and mix in. Chop roughly (about 1/2")
- fruit - raw only, things like: apples, pears, bananas, melon (any type), peaches, plums, blueberries - chop like veggies
- eggs either soft or hard boiled or lightly scrambled, raw eggs can bind to the B vitamins
- canned salmon, jack mackerel (inexpensive in our area, a 15-16 oz can runs about .89), sardines - mash any of these types of fish lightly, don't remove the skin or bones - great source of EFA's (essential fatty acids) and the bones are high in calcium. We'll split the can between our two and mix it with the kibble
- cooked oatmeal - spoonful or two
- yogurt - plain (preferable) or vanilla - low fat or non fat - spoonful or two
- grated cheese - light sprinkle of something like Romano, parmesan, cheddar
- cooked chicken - baked, broiled, boiled - remove skin/bones and chop it up some
- cooked beef/lamb - as above
- peanut butter - 1 spoonful
- broth - home-made or canned, no salt or low salt - a few spoonfuls to moisten the kibble a little but not to make it mushy
We don't give them "extras" every day since we feel to do so can start them getting to be picky and not eating if there isn't something besides kibble in their bowl. What we do is add something "extra" maybe 2-3 times a week at most and it's generally a little left over from our meal or something already in the fridge (like the yogurt or hard boiled egg). We eat a lot of fruit & veggies, so our boys will often get some pieces of fruit or veggies as a treat while I'm cutting them up for us. Our Mastiff is very allergic to many things, so we avoid commercial treats since he can't eat many of them without a flare - with the fruit/veggies we have no problems allergy wise.
Remove pits from fruits like apples, pears (they are toxic), skins are OK. Don't give grapes, raisins, onions as they are toxic to a dog.
Hope this helps
Excessive amounts of raw egg white isn't good though. Not an issue if you're only feeding a couple of eggs a week - but if it were daily (which, IMO, is too much anyway), it would be better to either ditch the white or lightly cook it.