I'm sorry I can't answer your questions but I have stopped using special dog shampoos and my dog no longer has skin issues after a bath. I just use plain Dawn dish detergent. Sounds crazy, but I read it as safe online and it does seem to help. I wonder if it would help you. Not sure what makes the coat hard. I have a corgi mix who looks like a corgi but her fur is really soft. Maybe that is unusual. I wonder if it is normal for their coats to get harder in purebreds, but the flaking sounds unusual so it may be an irritation of some type. I'm sure someone will have helpful answers.
How often are you giving him a bath? He really doesn't need to be bathed unless he gets into something stinky. Corgis fur sheds dirt quite easily. Mud seems to just fall off as it dries. It sounds like he has dry skin and therefore dry hair, most likely caused by too many baths. Try to lay off the baths, increase the GENTLE brushing, and perhaps add a salmon oil capsule to his food. I use the human salmon oil capsules you can find in the big box store with the blue and gold logo (hint, hint) in the human supplement aisle. Rocky and Rosie just scarf it down whole when I toss one per day into their kibble. Salmon oil is great for a nice coat and also good for their joints.
I agree with Karen and the few times that my dogs get into something that they consider great...I use my organic shampoo.
How often do you wash the pooch? I don't wash my dogs more than a couple of times a year, and that only in the summertime when it's warm enough that they won't get chilled. It's not good for a dog's skin to be washed too often.
Ordinary baby shampoo should do the job, if "mild" is what's desired. I use plain human shampoo (yeah, I know, but it's never had any untoward effects) followed by a little human conditioner and a thorough rinsing.
An adult dog's fur is longer and coarser than a puppies. It may be that you're just seeing the start of the normal change in the animal's coat as he matures.
Too many baths can dry the skin out and therefore their coats. My Katie is a retired show dog and if I don't get her in to be groomed every 6 weeks her coat gets lots of waves and curls. Max is a fluffy and he tends to get very dry skin in the winter...we live in NY...so I started giving him fish oil capsules, same ones I take. He stopped with the dry skin and the fish oil also can have the same heart benefits for dogs as it does for humans. Actually the reason Katie goes in every 6 weeks is simply because Max needs to go to keep his longer coat neat so I take them together.
now that hes getting older his adult coat is coming in so this is normal. Baden had really rough and a wavy top line and i found out its due to it being dry so i mix 1/2 table spoon of conditioner and 1/2 of water in a spray bottle and take a comb to part the hairs going against the grain and spray under the waves. i then take a boar bristle brush and brush down his back in small strokes. if the ends flip up i take the comb to the end of his hair, spray more conditioner, and then use the bristle brush and work it through smoothing out the ends. i use isle of dogs every day shampoo and conditioner and have seen a huge improvement in both his skin and coat. also, fish oil really helps dry skin :)
The rougher coat happened with Nutmeg (my corgi) as she was leaving puppyhood and moving toward becoming a dog. But, we brush her every day with a boar's bristle brush and that helps with keeping down dog fluff around the house as well as keeping her coat shiny, less course, and less wavy. And, we use Burt's Bees Puppy Combined Shampoo and Conditioner. We bath her about once a month because she spends a lot of time outdoors. She's soft, shiny and clean. No issues with dry skin or dandruff. Good luck.
My personal thoughts are to go with a better diet for Yayo, and limit the amount of bathing time. Dogs usually don't need 'regular' baths, unless they roll in something putrid. His skin may be irritated by frequent baths, drying his skin and causing flaking. If you have to bathe Yayo, try an oatmeal shampoo. I have always used Horseman's Dream Rosewater Shampoo on our dogs, partly because it does a super job on my horses. Non-irritating, and gives the coat a great sheen.
What Yayo eats is likely the most important issue here. Try Orijen large breed puppy, or Fromm Surf and Turf. Our now-grown Corgi, and two Aussies have done very well with the feeding regimen. Orijen is very pricey, and Fromm is also expensive, but feeding one Corgi should not break the bank hopefully. DogfoodAdvisor.com can offer some good insights on other good foods. Look for Omega 3 levels.
Interesting about the fur on his back. From what I've read it's normal for corgies to have more coarse hair on the back, near the shoulder blades, that feels harder than the rest of the body. There's a legend about Corgi Riders (fairies) that used them for protecting their land and where the sadle would go is where the fur turned coarsed. :)
The diet has a role to play in the quality of his fur, the brushing and also the number of washes you'll allow. I would certainly bring him to the vet to have check out those flakes but it does sound like dry skin. I would mostly recommend if he's dirty a bit to just rinse with water or dry brush. In luke warm water that's what I do with little Wally when he's messy with thawing snow and slush. I only give him a bath when he gets into something nasty or has been playing with lots of dogs over the weekends and his full of dried drool.
Oh and yes, the part where the fur is thicker or coarse, that goes haywire after a bath. I dry him off with a towel and the curles come up, especially on the ridge of his back and buttock area. It's pretty funny but less since he's older.