Allergy and Dermatology for Equine and Small Animals, PLLC 

 Mc Kinney,TexasChristine Rees, DVM, DACVD

Autoimmune Skin Disease

INTRODUCTIONYour pet has been diagnosed with an autoimmune skin disease. Several different

autoimmune skin diseases exist in humans and in animals. The treatment and prognosis will vary

depending on which autoimmune disease is present. The different types of autoimmune skin

disease are:

1)  Lupus type (i.e. systemic lupus erythematosus or SLE, discoid lupus erythematosus or

DLE).

2)  Pemphigus (pemphigus erythematosus or PE, pemphigus foliaceous, PF, pemphigus

vulgaris or pemphigus vegetans)

3)  Bullous pemphigoid

The treatment options and prognosis will dependent on the type of autoimmune skin disease

that is present. Therefore, it is very important to get a definitive diagnosis of the type of 

autoimmune skin disease that is present. Skin biopsies and blood work are usually required for

the diagnosis and treatment plan.

LUPUSThe two lupus skin diseases are systemic lupus and discoid lupus erythematosus.

Systemic lupus usually has other problems other than the skin disease (i.e. joint pain,

kidney disease, heart problems, neurological problems, etc). The types of skin lesions orsores are nonspecific (crusting, scaling, ulcers, hair loss, redness of the skin, etc.) with

only occur in 20% of the cases of dog SLE. Discoid lupus erythematosus is much more

common in animals. DLE has a variety of different skin lesions associated with it (i.e.

crusting, scaling, hair loss, ulcers, etc). The areas of the body that are affected are theface, ears, legs, mouth, and genital area. One or more of these body locations may be

affected. Itching and pain may be present but this finding is not always present (i.e.

variable). Breeds of dogs which are predisposed to developing DLE include: Collies,German shepherds, Shetland sheepdogs, Siberian huskies, Brittany spaniels, and German

shorthaired pointers.

PEMPHIGUSFour different types of pemphigus exist which are pemphigus erythematosus,

pemphigus foliaceous, pemphigus vegetans and pemphigus vulgaris. The most common

type of pemphigus in dogs, cats and horses is pemphigus foliaceous (PF). PF is initially apustular skin disease (i.e. acne type lesions). With time these pustules rupture open and

turn to crusts and then the become scale. Some crusts may coalesce (grow together)

crack and ulcerate or form an erosive lesion. Hair loss may be found in the areas wherethe skin lesions are present. Body areas that can have skin lesions are the face, nose,

 

ears, body, legs, groin, nails, nail bed, mouth (rare) and footpads. One or more of these

body locations may be involved. Itching and pain is variable. Some dogs may show signsof lameness when the footpads are affected.

The second most common type of pemphigus in dogs and cats is pemphigus

erythematosus. This type of pemphigus is thought to be a benign variant of PF.Therefore, clinically it can look similar to PF with the exception that oral or mouth

lesions are not usually present. Most dogs have skin lesions limited to the face and ears

but some animals will have lesions on paws or genitalia.

Pemphigus vulgaris is the third most common form of pemphigus. This form of pemphigus has vesiculopustular lesion (blister type lesions) that rupture open and

ulcerate. About 90% of these pemphigus cases have ulcers in the mouth, around the

rectum and genital areas. Other areas that may be affected are the armpits and groin.Secondary infections can occur and these skin lesions can be painful. In addition, some

dogs may have enlarged lymph nodes and have systemic signs (i.e. depression, anorexia

or not wanting to eat or have a fever).

Pemphigus vegetans is a proliferative crusting and scaling skin lesions mostcommonly found on the trunk or body. This form of pemphigus is rare. Itching and pain

are variable.

BULLOUS PEMPHIGOID

Bullous pemphigoid can look similar to pemphigus vulgaris (blister type disease that

ulcerates) clinically but is a totally different type of autoimmune skin disease. This

autoimmune skin disease is very rare.

TREATMENT OPTIONS AND RECOMMENDATIONS

1.  Steroidsa.  Immunosuppressive doses of oral (given by mouth) steroids are commonly

used to treat autoimmune skin disease. Several different types of steroids

exist. Some have been associated with fewer side effects when compared

to others. Common side effects for steroids are: increased drinking,increased urination, increased appetite, panting, enlarged liver, diabetes,

recurrent skin or urinary tract infections. This medication is usually

started at a high dose (induction phase) and then gradually decreased tothe lowest every other day or third day dose. This tapering schedule needs

to be very gradual so that the skin problem does not relapse. A minimum

of 2 weeks is usually required before the steroids can be tapered. Only 30to 40% of the autoimmune cases respond favorable to being maintained on

steroids only. Most dogs experience too many side effects and require that

a steroid sparing medication be added into the protocol.

b.  Topical steroids may be used to treat some forms of steroids. The sideeffects listed above may occur with topical steroids but are less common

than with oral steroids.

2.  Immunosuppressive drugs sometimes added into steroids to help reduce or

eliminate steroids necessary to control the skin disease.a.  Azathioprine or Imuran is an immunosuppressive oral (tablet) medication

which affects lymphocytes (both T and B cells) but has a slow onset (i.e. 4

 

to 6 weeks). Side effects reported with this drug include: bone marrow

suppression (decreased white blood cell count, decreased platelet count ordecreased red blood cell count), hepatotoxicity (increased liver values) and

pancreatitis. Because of these side effects, it is important to get blood

work (complete blood counts) every 2 weeks for the first 10 to 12 weeksof therapy. Once the disease is under control then the frequency may be

decreased to every 2 to 3 months. More extensive blood work to check for

liver problems or other systemic problems should be performed every 3 to

6 months depending on how the animal is doing.b.  Chlorambucil or Leukkeran is an immunosuppressive (tablet) medication

that has a slow onset similar to azathioprine. Side effects are bone marrow

suppression and mild GI upset. Monitoring for side effects is similar toazathioprine.

3.  Cyclosporine (Atopica or Neoral)

a.  This drug causes immunosuppression primarily through the T

lymphocytes. Side effects for cyclosporine include: GI (vomiting anddiarrhea, most common), gingival hyperplasia (proliferative growths in the

mouth), abnormal long hair coat, excessive shedding, toxic to pregnant

animals, renal disease (renal toxicity, high drug levels), liver disease(hepatoxicity, high drug levels), pancreatitis, and recurrent infections.

Many drugs can interact with cyclosporine so let your veterinarian know

what medications your dog is taking so that these drug side effects can be

avoided. Blood work and urinalysis are required prior to starting thismedication and periodically depending on how the animal is doing. In

addition, if the animal is doing poorly on this medication, drug levels may

need to be taken in order to try to adjust the drug dose. Cyclosporine isnot approved for use in cats.

4.  Tacrolimus

a.  This is a topical immunosuppressive drug similar to cyclosporine. The

most common but rare side effect of tacrolimus use in dogs is burning orirritation to the skin. Since the FDA has reported that laboratory animals

may have developed cancer after topical use of tacrolimus, gloves should

be worn when using this medication.5.  Tetracycline and Niacinamide (works best for cases of DLE)

a.  Tetracycline is an antibiotic that has anti-inflammatory and

immunodulating actions (ie suppresses lymphocyte transformation,antibody production, and inflammatory mediator ( i.e. prostaglandin)

synthesis. This antibiotic can cause problems with teeth in young dogs

(i.e. enamel formation), photosensitization (sensitivity to sunlight) and GI

(i.e. vomiting and diarrhea). Since milk products and anti-acids can bindto this antibiotic, this medication should not be given when tetracyclines

are being given.

b.  Niacinamide is known to block antigen induced histamine release and

prevent mast cell degranulation and release of inflammatory mediators.Side effects include: anorexia (not wanting to eat) and elevated liver

 

enzymes. Please be sure to use niacinamide and not niacin. These

products are NOT the same.6.  Avoidance of sunlight and sunscreen

a.  If possible, extreme sunlight exposure should be avoided between 8 am

and 5 pm.b.  If a pet with autoimmune skin disease is outside (regardless of the type)

then sunscreen should be worn. A minimum SPF of 30 with a waterproof 

base which is safe for children can be used safely on dogs. The sunscreen

should be applied within 1 to 2 hours prior to sun exposure and reappliedevery 4 hours if constantly outside.

PROGNOSIS AND OUTCOMEThe prognosis is variable depending on the type of autoimmune disease present.

DLE, PE, PF are usually readily controlled and most dogs have a fairly normal life with

treatment. Pemphgius vulgaris and bullous pemphigoid are difficult to treat and

sometimes do not always have a favorable outcome even with treatment. Pemphigusvegetans is one of the more rare autoimmune skin diseases and it has the least amount of 

information. Historically, pemphigus vegetans can be difficult to treat and animals with

this problem do not always have a favorable prognosis.Autoimmune skin disease requires life long treatment for the affected pet. They do

not go away. Periodic monitoring with blood tests may need to be performed depending

on which treatment is being used.