Skin Bumps (Papulonodular Dermatoses) in Dogs

Papulonodular Dermatoses in Dogs

Papulonodular dermatoses are skin diseases that are characterized by papules and nodules on the skin. These are bumps that are found on the surface of the skin, and which have a solid appearance without liquid or pus within (nonsupperative).

Symptoms and Types

Papules are the result of tissue infiltration by inflammatory cells. While nodules, which are larger than papules, are the result of a massive infiltration of inflammatory or cancerous cells into the layers of the skin.

Causes

• Superficial and deep bacterial infection of the hair follicles
• Fungal infection of the hair follicles with a secondary bacterial infection; may include raised, pus-filled, spongy lesions
• Ringworm
• Sebaceous (oil) gland inflammation
• Acne
• Mange
• Nematode infection
• Bodily cells crowding into the skin (eosinophils, white blood cells that eat bacteria, fight parasites or macrophages)
• Reaction to sunlight
• Neoplasia (abnormal tissue growth)

Diagnosis

You will need to give a thorough history of your dog's health, onset of symptoms, and possible incidents that might have precipitated this condition, such as an excessive amount of time in the sun, new foods that might have cause allergic responses, recent infections with parasites, etc.

Standard tests will include a complete blood profile a chemical blood profile, a complete blood count, and a urinalysis. During the physical exam, your veterinarian will scrape your dog's skin gently with a scalpel in order to get samples of the hair and skin for testing. This will allow your veterinarian to check for parasites, bacteria and/or yeast infections, any of which may be causing the skin to react with the raised nodules and papules. Cultures of these samples will be sent to a laboratory to check for fungi, bacteria, and microscopic parasites. Skin samples will also be sent for analysis on a microscopic level.

Treatment

The medicines prescribed will depend on what the underlying cause of your dog's skin disease is. Your veterinarian may prescribe oral or topical (or both) antibiotics if bacteria are present. If your dog has parasites, it will need to be bathed and given a parasiticidal dip (a preparation that is used to destroy parasites).

If your dog is having a reaction to sunlight, you will need to limit your dog's exposure to sunshine between 10 a.m. and 4 p.m., or apply sun block that is safe for use on dogs.

For cases of squamous cell carcinoma, a form of skin cancer, the long-term outlook is poor. If your dog is a good candidate for surgery, your veterinarian will counsel you on your options. Often, surgery in conjunction with other therapies is necessary.

Living and Management

You will need to revisit your veterinarian as often as recommended for chemical blood profiles, complete blood counts (CBC), urinalyses, and electrolyte panels if your dog is receiving cyclosporine, retinoid therapy or synthetic retinoid therapy.

Dogs with mange should be monitored until they show no more signs of the infection, while those with ringworm will need to have fungal cultures repeated until they have a clear return.