When dogs suffer from dermatitis, there may be a bad smell that comes from them. This is called seborrhea and is a common symptom of dog skin allergies. There are many causes of dog skin allergies, and because there are a variety of causes, it is quite difficult to identify and diagnose. However, the bad smell that can come with it is a pretty clear indication. Seborrhoea s caused when the outer most layers of the skin are over productive. This results in dullness, flaking skin, and oiliness of the skin. The skin components that are especially responsible for this are the sebaceous glands and the follicle. They produce the oily sebum, which becomes rancid. This is clearly, then, the source of the odour that often accompanies dog skin allergies. If you try to solve this problem with frequent bathing and harsh dog shampoos you may merely increase the problem and exacerbate the condition and the smell.