My dog is fed Royal Canin Veterinary Urinary S/O Dry Dog Food at breakfast time, for tea-time she gets raw chicken (chopped up drumstick or wings and 1/4 frame) with Vets All Natural Complete Mix Adult Senior mixed in.
She did have bladder stones/struvite crystals (that's why the Urinary S/O) and suffers from some itchiness on her haunches; she licks them and her bum as well, her anal glands were expressed but she still licks.
After her struvite crystals diagnosis and treatment there h
this is the dry food she is eating in the morning:
https://www.petstock.com.au/product/dog/royal-canin-veterinary-urinary-s-o-dry-dog-food/58497
and a list of the ingredients, as you see they are pretty crappy, no wonder her skin is going black...an awful amount of corn, fillers and sodium to make her wee more often therefore drinking more to flush the kidneys
Rice, maize flour, animal fats, dehydrated poultry meat, maize gluten, minerals, hydrolysed animal proteins, vegetable fib