Why Does My Dog Have Really Bad Dandruff?

Why Does My Dog Have Really Bad Dandruff? Why Does My Dog Have Dandruff? Dandruff appears when your dog’s sebaceous glands over-produce an oil called sebum. This oil helps keep your precious pup’s skin moist and healthy. However, when the sebaceous glands produce too much oil, it causes an imbalance, which in turn causes dandruff.