What is seborrhea?
Seborrhea, or seborrheic dermatitis, is a skin disorder in which the sebaceous glands of the skin produce an excessive amount of sebum, causing scaly, flaky, itchy, and red skin. Seborrhea typically affects the back, face, and flanks and is worse in the folds of the skin. There are two types of seborrhea: seborrhea sicca (meaning dry seborrhea) and seborrhea oleosa (meaning oily seborrhea). Most dogs with seborrheic dermatitis have a combination of dry and oily seborrhea.
What are the clinical signs of seborrhea?
In dogs, seborrhea usually affects skin areas that are rich in sebaceous glands, especially the skin along the back. The affected areas of skin often flake off like dandruff that can be seen on the dog's bedding and other places where the dog lies. Some skin areas may be red and inflamed, with either a dry or oily feel to the lesions, and may be worse in areas with skin folds, such as the feet, neck, lips, armpits, thighs, and underside. Many dogs will have an odor associated with seborrhea. This odor is usually worsened if the seborrhea is complicated by a secondary bacterial or yeast skin infection.
What causes seborrhea?
Seborrhea can be a primary or secondary disease. Primary seborrhea is inherited and occurs in breeds such as Cocker Spaniels, West Highland White Terriers, and Basset Hounds. Secondary seborrhea is more common; however, the exact cause cannot always be determined. In these cases, it is called idiopathic seborrhea.
Secondary seborrhea is often related to an underlying medical problem, such as:
- Hormonal imbalances (e.g., thyroid disease, Cushing's disease)
- Parasites (e.g., fleas, ticks, mange mites)
- Fungal infections - especially yeast skin infections (Malassezia)
- Bacterial infections
- Dietary abnormalities (i.e., diets containing low levels of omega-3 fatty acids)
- Environmental factors (e.g., temperature, humidity changes)
- Obesity or musculoskeletal disease making the dog unable to groom properly
How is seborrhea diagnosed?
Tests that can aid your veterinarian in diagnosing your dog's seborrhea include:
- Complete blood cell count (CBC), serum chemistries, and electrolytes to look for subclinical or hidden underlying conditions or imbalances
- Skin cytology and skin biopsy to assess for inflammatory cells, bacteria, yeast, fungus, or abnormal cells
- Skin scrapings and hair pluckings to check for external parasites
- Skin culture to test for bacterial and fungal infections (i.e., ringworm)
- Hormone tests to check for hormonal imbalances (e.g., thyroid disease, Cushing's disease)
How is seborrhea treated?
Treatment is aimed at the underlying cause. If no underlying cause can be found, then a diagnosis of primary or idiopathic seborrhea is made. Unfortunately, there is no specific treatment for primary or idiopathic seborrhea.
In general, treatments that help manage seborrhea include:
- Omega-3 fatty acid supplements
- Anti-seborrheic shampoos or sprays
- Oral cyclosporine (Atopica®)
- Antibiotics to treat secondary bacterial infections
- Antifungals if yeast infections are present
What is the prognosis for seborrhea?
The prognosis for seborrhea is based on your dog's specific condition and its severity. The prognosis is better if an underlying cause is identified and treated. Your veterinarian will discuss a diagnostic and treatment plan for your dog to help you manage this common and often frustrating condition.