The internet is full of mis-information, Google does not fact check. Unfortunately from time to time, Vets will also post mis-information in relation to nutrition, just because a Vet says something, doesn't make it fact - question everything, even if you see something on a "science" website, we want to check the sources.
A story that comes and goes fairly consistently is that you should not feed raw eggs to your dog because the egg whites contain a biotin inhibitor called Avidin and this leads to a biotin deficiency. If only nutrition and our bodies were that black and white!
Fresh food feeding is based on the premise of feeding a variety of ingredients to avoid underdoing or overdoing any one nutrient and there is a bunch of food that has biotin in that you would be rotating though such as:
Egg Yolks < Yes, you read that right, egg yolks contain Biotin so just feed the entire egg not just the whites...who would just feed the whites anyway?!
Legumes
Nuts and Seeds
Liver
Sweet Potatoes
Mushrooms
Bananas
Broccoli
Brewers & Nutritional Yeast
Avocado
Blueberries
Egg Shells
Sardines
Cauliflower
Pork
Turkey
Beef Kidneys
Green Leafy veggies
So if you're feeding a bunch of biotin, is this something you need to be scared of? To break down the issue, the 'potential' problem with consuming raw eggs regularly is that raw egg whites contain a protein called avidin which binds biotin and prevents its absorption. It would take more than two dozen egg whites consumed daily over many months to cause a deficiency, making this an unlikely occurrence(1).
Cooking was thought to denature avidin and prevent it from binding biotin, meaning that cooked eggs were not a concern but guess what...there's science to say different... When cooked, avidin is only 'partially' denatured and binding to biotin is reduced, one study showed that 30-40% of the avidin activity was still present in the egg white after frying or boiling(2). So, why does this matter? Well, that would mean the 'potential' problem of biotin deficiency in humans would be a legit issue for people who consume eggs on a regular basis BUT biotin deficiency is incredibly rare in humans...food for thought. Is this really an issue that we need to be worried about? I would challenge you as a pet parent to look into your dogs diet regardless of if they're eating eggs or not to see if your dog is obtaining enough biotin in their diet. A deficiency of biotin can be related to a number of skin and coat conditions (as are a number of other nutrient deficiencies)
Image: Dogs Naturally
Supplementation If you like, you can actually supplement with Biotin, it's a water soluble vitamin so you can't over do it, the excess would just be flushed.
As per the above listed study(3), the dose was 5mg of Biotin per 10 kilos of body weight per day and the the study was over 3 to 5 weeks . You can purchase human biotin capsules, and do the math. Pure Biotin powder is very expensive but you can also research suppliers. There are a range of equine products that are typically calcium + biotin and you would be able to do the math on how much to give.
Dog products for your research:
--- (1) Whitney E, Rolfes SR. (2008) Understanding nutrition. Belmont, CA: Thomson Wadsworth. (2) Durance TD (1991). "Residual Avid in Activity in Cooked Egg White Assayed with Improved Sensitivity". Journal of Food Science. 56 (3): 707–709. doi:10.1111/j.1365-2621.1991.tb05361.x. (3) https://pubmed.ncbi.nlm.nih.gov/2602924/