Discoid lupus erythematosus (DLE in dogs) occurs when the immune system attacks the skin on and around the nose, leading to pigmentation loss, ulceration, and crusting. Integrative veterinarian Dr. Julie Buzby discusses the causes, symptoms, diagnosis, treatment, and prognosis for dogs with DLE to help dog parents learn about this autoimmune skin disease.
Dogs, humans, and other species can suffer from autoimmune diseases—conditions that occur when the immune system attacks cells in the body. While some autoimmune conditions can impact multiple organs or systems, others are more limited in scope. One of the more frequently diagnosed localized autoimmune skin conditions in dogs is discoid lupus erythematosus (DLE).
What is DLE in dogs?
DLE (discoid lupus erythematosus) is a common autoimmune skin disease that occurs as a result of the immune system targeting the skin that makes up and surrounds a dog’s nose. Also known as nasal solar dermatitis or collie nose, DLE can cause symptoms ranging from a loss of normal nose pigmentation and a decrease in cobblestone appearance early in the disease to crusting and ulceration of the tissue surrounding the nose during the later stages.
Other forms of cutaneous lupus
While DLE is the most common type of cutaneous (skin-specific) lupus, it is far from the only one. Instead, it is part of a larger syndrome called cutaneous lupus erythematosus (CLE). Other less common variants of CLE include:
Exfoliative cutaneous lupus erythematosus (ECLE)
ECLE is a progressive disease with a poor prognosis, affecting some puppies as early as 10 weeks of age. German Shorthaired Pointers and Vizslas are commonly affected. Initial signs include scaly, flaky skin on the face, ears, and trunk. But symptoms may progress to fever, lethargy, lameness, and enlarged lymph nodes.
Mucocutaneous lupus erythematosus (MCLE)
MCLE primarily affects German Shepherds and their crosses. The disease causes large, crusted, painful sores and hyperpigmentation of the skin at the mucocutaneous junctions (places where haired and non-haired skin meet) of the eyelids, lips, nostrils, genitalia, and anus.
Vesicular cutaneous lupus erythematosus (VCLE)
VCLE typically affects middle-aged to senior Collies, Shelties, and their mixes. It causes blisters on the skin, especially in the armpits, groin, inner thighs, abdomen, and around the mouth. When the blisters rupture, they form large, painful ulcers.
Systemic lupus erythematosus—the generalized form of lupus
In contrast to these cutaneous syndromes, dogs can also develop systemic lupus erythematosus (SLE). This is a generalized autoimmune disease that affects tissues and organs throughout the body. SLE in dogs is a relatively rare condition. But it is one that is potentially fatal due to its ability to cause widespread organ damage.
What causes discoid lupus erythematosus in dogs?
Veterinarians believe DLE is triggered by ultraviolet (UV) light from excessive sun exposure (hence the name solar dermatitis). UV radiation causes inflammation in the sensitive tissue layers of the face, including the nasal planum (the hairless, pigmented part of the nose). This can set off an immune reaction.
Other potential culprits for the onset of lupus symptoms include stress and exposure to cigarette smoke. These factors play a much bigger role in the development of DLE in humans. But they can also be possible immune system triggers for dogs.
Since DLE is caused by the immune system attacking cells around the nose, it is not contagious to other dogs.
Which dogs tend to get DLE?
Most dogs with DLE range in age from young adult to middle-aged. Certain dog breeds seem to have a genetic predisposition to DLE, including:
- Alaskan Malamutes
- Brittany Spaniels
- Chow Chows
- Collies
- German Shepherds
- German Shorthaired Pointers
- Shetland Sheepdogs (Shelties)
- Siberian Huskies
Because of the hereditary potential, dogs with DLE or a history of DLE in their bloodlines should not be used for breeding purposes.
What are the symptoms of discoid lupus in dogs?
Symptoms of DLE can be divided into early symptoms and later symptoms.
Early signs of DLE
Initially, symptoms of discoid lupus erythematosus in dogs include:
Pigment loss on nose and around eyes
Instead of being dark brown to black, the nose will start to lose its pigmentation and become greyish to pinkish. At the start, DLE can look a little like snow nose in dogs, a harmless pigmentation change that occurs in some dogs in the winter.
In addition to pigment loss of the nasal planum, some dogs with DLE may experience depigmentation around the eyes.
Loss of nose texture
The nose may look and feel smooth in areas rather than having the normal cobblestone (bumpy) texture.
Later signs of DLE in dogs
As DLE progresses, affected dogs may also experience:
Scaling and redness of the nose
The nose may look dry or flaky. Plus, instead of being a nice light pink, the tissue surrounding the nose may be more of an irritated reddish color.
Skin ulceration
Affected dogs may develop ulcerated areas of skin on the nasal planum and bridge of the nose. Over time, DLE may progress to affect the skin of the ears, eyes, and genitalia. You may also notice hair loss in those areas.
Sloughing skin
As the surface layers of skin die, it may look like the skin is peeling off the underlying tissue.
Bleeding
Areas of abnormal skin may begin to bleed due to blood vessel damage. This is especially common in places where there is deep skin ulceration. Sometimes the blood will even spurt out.
Head to the vet if you see changes in your dog’s nose
At the start, DLE may not bother your dog much. However, the ulceration and sloughing skin that occur later on in the disease can be painful. Thus, if you notice changes to the color or texture of your dog’s nose or other skin changes, please make an appointment with your vet. The sooner you get to the vet, the sooner your dog can start feeling better.
How will the vet diagnose a dog with DLE?
Diagnosing a dog with DLE requires a combination of symptoms and biopsy findings, plus ruling out other similar conditions.
Biopsy
To definitively diagnose discoid lupus erythematosus in dogs, the vet will need to obtain biopsies of the affected area. This involves the vet placing your dog under anesthesia, then taking several small samples of the tissue, which your vet will submit to the diagnostic lab for microscopic evaluation.
Note: DLE, mucocutaneous pyoderma (a type of skin infection), and leishmaniasis (a parasitic disease) may all look similar on biopsy. The pathologist and family vet will need to take your dog’s history, environment, and response to antibiotics into consideration when interpreting the biopsy results.
Blood and urine tests
Prior to anesthetizing your dog for the biopsy, your veterinarian may recommend blood tests for dogs and a urinalysis. These tests are a good way to assess your dog’s overall health.
Ruling out other conditions
DLE can look very similar to many other skin conditions. As part of the diagnostic process, the vet will try to rule out:
- Fungal and bacterial infections: Ringworm (fungus) or Staph infections (bacteria) can create skin lesions that can mimic the appearance of DLE. To complicate matters, dogs with DLE may also develop secondary infections.
- Nasal hyperkeratosis: Dog nose hyperkeratosis is an abnormal overgrowth of skin cells on the nasal planum. It is often associated with DLE, but can also accompany other conditions, and is not an immune-mediated condition itself.
- Other types of autoimmune skin diseases in dogs: Pemphigus foliaceus (PF), which causes widespread skin lesions and hair loss, and VKH-like syndrome, which specifically targets the melanocytes responsible for the production of melanin pigment, can both look a bit like DLE, too.
Based on all the information the vet collected during the diagnostic process, he or she will reach a diagnosis and determine the best treatment plan.
What is the treatment for discoid lupus in dogs?
Once the vet makes a diagnosis of DLE, the main goals of therapy are to suppress the overactive immune response and relieve inflammation. Treatment often includes:
Immunosuppressant therapy
Oral and topical medications like prednisone for dogs, cyclosporine, tacrolimus, or betamethasone help decrease the immune system’s attack on normal cells. This makes them very useful for many immune-mediated conditions, including DLE. Once your dog’s skin heals, the vet may attempt to taper these medications to the lowest effective dose.
TIP: If your vet prescribes a topical immunosuppressant, consider taking a walk with your dog or playing with mental stimulation toys or games for dogs for about 10 minutes after applying the medication. This can distract your dog and decrease the chances he or she will try to lick the medication off the nose.
Antibiotics
The vet may prescribe antibiotics to treat any secondary infections prior to performing a biopsy. This is important because infection and DLE look very similar under the microscope.
Plus, treating with antibiotics before performing the biopsy helps rule out mucocutaneous pyoderma (bacterial skin infection that affects the lip margins, nose, eyelids) as the cause of the symptoms.
Doxycycline and niacinamide
The vet will often recommend giving the antibiotic, doxycycline, and B-vitamin supplement, niacinamide, together during treatment of DLE. This combination is highly effective in controlling DLE symptoms.
Apoquel, an anti-allergy medication
Apoquel® (oclacitinib), a prescription medication usually used to manage seasonal allergies in dogs, may be helpful for dogs with chronic cases of DLE, too. A small study published in Veterinary Dermatology looked at treating cutaneous lupus in seven dogs with Apoquel. It revealed that Apoquel led to complete remission of symptoms in six of seven dogs within two months of starting therapy.
The potential benefits of Apoquel therapy include oral dosing with a palatable chew tablet and a rapid onset of action. Plus, it has a low likelihood of unpleasant side effects compared to the other systemic immunosuppressive drugs that we’ve discussed.
Omega-3 fatty acids
Omega-3 fatty acids for dogs (found in fish oil) are well-documented to have anti-inflammatory properties and are great for supporting the skin. Your veterinarian can recommend a high-quality fatty acid supplement that you can add to your dog’s daily mealtime or treat routine.
Doggy sunscreen
Your vet may also recommend using a dog-safe sunscreen on your dog’s ears, face, and muzzle to protect from future flare-ups. It is important to use a product made for dogs, as human sunscreen may contain ingredients that are toxic to dogs. Also, do not start applying sunscreen until any ulcerations on the nose have healed up.
What is the prognosis for dogs with DLE?
Because DLE usually only affects dogs’ skin around the nose and muzzle, the prognosis is generally good with treatment. Color should return to the nasal planum, but it may take several months to do so. However, it is important to remember that some dogs may have relapses of DLE in the future.
Veterinary researchers have also noted that chronic DLE can occasionally lead to the development of a type of cancer called squamous cell carcinoma. If your dog has been treated for DLE but develops a new suspicious area on the nose or face, it’s a good idea to have your vet recheck those areas as soon as possible.
Take heart—DLE is manageable
Immune-mediated conditions like DLE can be confusing and stressful since there’s often no obvious answer to why a dog’s immune system attacks its own healthy cells. However, the good news is that DLE is a manageable condition. With prompt treatment and good communication between you and the veterinary team, your sweet dog can continue to enjoy a comfortable quality of life.
Has your dog been diagnosed with DLE?
Please share his or her story below.
