Dogs will often start to look a little bit unkempt, develop a greasy coat and dandruff if they are feeling poorly.
Dogs tend to groom themselves a bit less once they get older, often due to arthritis and stiffness.
If your dog is in pain, they are likely to spend less time grooming.
Skin infections due to bacteria, yeast or fungus (such as ringworm) usually cause flaky skin.
Mites and lice
Parasites such as mites and lice can cause very itchy, flaky skin.
Fleas cause itchy skin, scratching is likely to cause dandruff.
Allergic skin disease
Atopic dermatitis, food allergies and flea allergies can all cause itchy, dry, flaky skin.
Hormone problems such as hypothyroidism or Cushings disease often affect the skin.
Immune system problems
Autoimmune skin disease such as pemphigus causes scaly skin.