Seborrhea is not a diagnosis, it is a symptom of an underlying disease, such as skin infection (bacterial, yeast), hormonal disease (hypothyroidism, Cushing's disease), parasites (cheyletiella, demodex), nutritional or fatty acid imbalance, allergies, liver disease, etc. In an older dog, the first step is to perform full labwork and thyroid panel to identify any internal diseases, and to perform skin scrapings and skin cytology to look for skin parasites and infection. If bloodwork abnormalties are found, then further diagnostics/treatment are prescribed based on the lab results. If skin infection is found, then antibiotics for 3-4 weeks would be needed. Because cheyletiella mites can be difficult to find on scrapings, I usually trial treat scaly dogs for these mites by applying Revolution spot on every 2 weeks for 3 treatments. Additionally, Demodex injai is a fairly newly described microscopic skin mite that causes oily scale preferentially on the back of terriers, and can be harder to find than the typical demodex mite.
Topical therapy with antiseborrheic shampoos can help reduce scaling; Pyoben is good for oily scaling, but is too drying if the scaly skin is dry to begin with; a better choice, if that is the case, would be Sebolux or Douxo shampoo, followed by a conditioner. However again, these products are not addressing the cause of the scaling, and I recommend talking to your veterinarian about going further diagnostically, or referring you to a veterinary dermatologist (www.acvd.org).
Kimberly Coyner, DVM DACVD
Dermatology Clinic for Animals of Las Vegas
Thank you for the information. If it's mites or mange, wouldn't my other dog have contracted it by now? This dog has had this problem with increasing severity for a couple of year now and my other dog does not show any signs. My vet told me it was related to her allergies, but I will discuss further testing with them.
Cheyletiella mites are transmissible to other animals, however Demodex mites are not. Good luck, let us know what you find out.