Seborrhea is an inherited disorder which affects the outer layer of skin in a dog. The skin's sebaceuous glands (which produce a fatty substance called sebum) and hair follicles are much more productive than is normally the case. The result is that skin can become both dry and greasy at the same time, producing both a hard, scaly texture and a loathsome oily ichor that coats the entire body of the dog. Seborrhea usually manifests by the time of a dog's first birthday and the first outbreak of the disease is usually quite memorable to owners who are unfamiliar with the rancid odor that the abundant grease can produce.
All breeds are subject to seborrhea, but in particular Spaniels and Terriers. A higher than average tendency towards the disorder is also seen in the Irish Setter, the German Shepherd, the Dachshund, the Doberman Pinscher, the Shar-Pei, and the Labrador Retriever.
Seborrhea is diagnosed by the observation of a mild flaking of the skin and the coat losing its luster, taking on a dull lifeless shade. This usually starts to happen at around 10 weeks of age, with more dramatic signs such as the characteristic stink manifesting by the age of 18 weeks. The coat will take on a greasy feel and lose all of its shine, the ears will become increasingly prone to a dark waxy buildup and you may also notice a thickening of the dog's paw pads. In addition, claws will become dry and brittle and break off. If you find broken claws frequently lying around the floor of your home, it's a possibility that seborrhea is on the horizon.
Seborrhea is primarily a cosmetic disease that doesn't really effect the overall health of the animal, but even so the scratching necessitated by dry and flaky skin can cause trauma that might develop a secondary baterial infection. In any case, a skin biopsy is always necessary to rule out more malignant causes of similar symptoms, such as skin cancer.
Treatment for seborrhea involves the diligent treatment of any developing secondary infections with antibiotics and ointments. The disease itself is incurable and so treatment will be a life-long process. Anti-seborrheic shampoos and moisturizers are prescribed most often, as well as frequent bathing. Typically, an after bath rinse is also used to help the skin retain natural moisture.
Constant monitoring of the effected animal is also necessary in order to forestall the possible development of secondary infections. These can result not just from skin lesions as described above, but also from clogged ear canals or broken mucus membranes.
Dogs that suffer from seborrhea should not be bred, as it is an inherited disease.