Inflammatory Skin Disease in Dogs

Inflammatory skin disease, also referred to as sebaceous adenitis, is a rare skin condition of unknown etiology.  The process of inflammation begins at the sebaceous glands which are located within the skin layer and function to secrete lubricating oils into the hair follicles.

Inflammatory skin disease commonly manifests as itchy, scaly skin, with patches of hair loss.  Dogs can exhibit crusty lesions and in severe cases will develop a secondary bacterial infection.  Depending on the severity and progression of the disease, treatment can be extensive and costly.

Inflammatory skin disease affects the glands in the skin that secrete essential oils for hydration.  Common symptoms are scaly skin and hair loss.  Chronic inflammatory skin disease is expensive to treat and has a poor prognosis.

Symptoms usually manifest across the dorsal back and top of the neck, then spread towards the face or tail.  Symptoms include:

• Alopecia (hair loss)
• Crusty lesions
• Scaly skin
• Follicular casting (scales that stick to the hair shaft)
• Moth-eaten’ appearance due to patchy hair loss
• Redness of skin
• Change in hair coat color
• Itchiness
• Excessive scratching
• Greasy skin
• Unpleasant smell of hair coat
• Pustules and purulent discharge due to secondary bacterial infection
• Development of ear infections

Inflammatory skin disease in dogs is an idiopathic disorder, meaning that the exact cause of the disease is unknown.  It can also be classified as an autoimmune disorder, in which the normal immune responses in the body are not functioning correctly.  A strong hereditary association has been found in Standard Poodles and there are certain other breeds that appear to be predisposed to the condition.  It occurs most commonly in middle-aged or young adult dogs.

Breeds predisposed to sebaceous adenitis include:

• Standard Poodles
• Akitas
• Samoyeds
• Havanese
• Lhasa Apsos
• Vizslas
• Springer Spaniels

Upon presentation, the veterinarian will take a complete history and do a thorough physical examination.  There are several other skin conditions that have similar clinical signs to inflammatory skin disease, therefore, there are several diagnostic tests that the veterinarian will perform to confirm a definitive diagnosis.

One of the first conditions that a veterinarian will want to rule out is the presence of ringworm (a fungal skin infection that is easily transmittable to humans).  The diagnostic test is known as a Wood’s lamp examination and uses an ultra violet light to look for luminescence of any lesions on the skin.  Depending on what is seen and additional suspicions, the veterinarian may also perform a fungal culture of the lesion or hair pluck to further rule out the ringworm infection.

Additional tests performed to rule out the differential diagnoses involve sample collection using skin scrapings and impression smears with adhesive tape.  Microscopic evaluation of the samples collected will be used to rule out demodectic mange and the presence of bacteria and yeast on the skin.  Blood samples may be taken to evaluate blood parameters for inadequate endocrine function which can sometimes contribute to alopecia and scaly skin lesions.

In order to confirm a definitive diagnosis of sebaceous adenitis, a skin biopsy will be collected.  The sample is obtained using a biopsy punch and is sent away to a histopathologist who will evaluate the sample for certain indicators consistent with inflammatory skin disease.

There will be a better prognosis if treatment is started in the early stages of the disease.  As inflammatory skin disease progresses, increasingly aggressive treatment will be required.  Treatment commonly requires multimodal (a combination of methods) management consisting of topical shampoos and ointments, oral medications and supplements, and in some cases injectable medications.

Early cases of inflammatory skin disease may respond to treatment with glucocorticoids, however as the condition progresses these becomes less effective.  Oral supplements include essential fatty acids and vitamins A & E.  Cyclosporine and prednisone medications may also be used as treatment.  Oral retinoid supplements (compounds that produce effects similar to vitamin A) can also be effective, however, they are expensive and can be difficult to obtain for veterinary treatment.

Medicated shampoos and topical therapy are aimed at softening the skin to improve the moisture binding capacity.  Baths can usually be performed at home but can be labor intensive for owners.  Care must be taken with mineral oil soaks and the use of keratolytic shampoos - dogs must be rinsed thoroughly.  Bathing is usually required every 2-4 days to begin with and repeated every 2-4 weeks for ongoing maintenance.

Antibiotic treatment may be necessary in chronic cases of inflammatory skin disease where the condition has developed secondary bacterial pyoderma due to an infection.

Treatment is generally required long-term for the management of inflammatory skin disease.  Symptoms are likely to reoccur after therapy is discontinued. 

Dogs will require continual reassessment by the veterinarian to monitor the effectiveness of the treatment prescribed.  Once noticeable improvement is seen, the dosages of supplements may be reduced and bathing may become increasingly intermittent, however if all therapy is completely stopped then the symptoms will reoccur.    

Inflammatory skin disease has a poor prognosis.  A full recovery from inflammatory skin disease is unlikely and ongoing treatment is essential.  Supplements and topical therapy are prescribed with long-term use in mind and typically have minimal negative side effects.  Fortunately, dogs that exhibit chronic inflammatory skin disease can live quite comfortably as long as the owner is willing and able to sustain continual treatment.

Treatment for inflammatory skin disease can be expensive due to the multimodal approach and necessity for ongoing treatment.  Diagnostic costs can range from $500 - $1600, due to the multitude of tests and requirement for external analysis of biopsy samples.  Treatment is often extensive and will range depending on severity from $4000 - $13000.