Lecture 44 (Autoimmune Diseases)

-affect planum (nose), pinnae (ears), and pads

-present with unusual or "weird" patterns

-may involve total body

-characterized by pustules rather than vesicles

-different from typical folliculitis patterns

what are the unique clinical patterns associated with autoimmune disease?

Pemphigus Foliaceus

what is the most common autoimmune skin disease?

-autoimmune skin diseases represent approximately 1.3-1.4% of veterinary dermatology cases

-they can be primary (spontaneous) or secondary (induced by drug reactions, paraneoplastic conditions, post-infection, or tissue damage)

what causes autoimmune skin diseases?

-recognize the clinical pattern

-perform cytology (acantholytic cells indicate pemphigus)

-complete blood count (CBC) and chemistry panel → look for inflammatory markers; SLE may show bone marrow or renal involvement

-ANA testing (positive in SLE and PE)

-skin biopsies sent to a dermatopathologist (essential for definitive diagnosis)

how should autoimmune skin diseases be diagnosed?

-Pemphigus Foliaceus/Erythematosus

-Discoid Lupus Erythematosus (DLE)

which autoimmune skin diseases have a good to fair prognosis?

-Systemic Lupus Erythematosus (SLE)

-Bullous Pemphigoid/Pemphigus Vulgaris

which autoimmune skin diseases have a poor prognosis?

-the goal is to control 90% of lesions 90% of the time, acknowledging the normal wax and wane process of these diseases

-control secondary infections

-suppress the immune response

-avoid UV light

how do you treat autoimmune skin diseases?

-topical and oral antibiotics

-topical Steroids or Protopic (0.1% Tacrolimus)

-nutritional support: essential fatty acids

-Tetracycline/Doxycycline and Niacinamide

-Cyclosporine (5-30mg/kg)

-Apoquel

-Glucocorticoid steroids at immunosuppressive doses

-chemotherapeutics (Azathioprine/Chlorambucil)

-Gold salts

which medications can be used to treat autoimmune skin diseases?

-acts through protease inhibition and immunosuppression

-few side effects (mainly GI signs)

-considered the most benign therapy option

MOA for Doxycycline/Tetracycline + Niacinamide in the treatment of autoimmune skin diseases

-treat until 80% response, then taper dose every 3 weeks

-goal is every other day dosing

discuss administering Steroids at an immunosuppressive dose for the treatment of autoimmune skin diseases

-characterized by pustules and crusts that wax and wane

-affects nose, ears, foot pads, trunk

-rarely affects mucocutaneous junctions

-presence of acantholytic cells on cytology is diagnostic

how do you diagnose Pemphigus Foliaceus?

-Discoid Lupus Erythematosus (DLE)

-common in Collies, German Shepherds, Shelties, Siberian Huskies, Brittany Spaniels, German Short-Haired Pointers

what is the second most common autoimmune skin disease (0.3% of canine dermatology)?

-known as "The Great Imitator"

-primary symptoms: arthritis (#1) and skin lesions (#2)

-can cause renal disease and bone marrow disease

what clinical signs are associated with Systemic Lupus Erythematosus (SLE)?

SLE cases

Antinuclear Antibody (ANA) test is 90% positive in which autoimmune skin diseases?

from drugs, infections (pyoderma), or technique issues

why are there many false positives with that ANA test in SLE cases?

-affects older dogs

-severe crusting on face, elbows, feet

-may present with liver failure

-requires biopsy for diagnosis

look-alike diseases:

what is Hepato-Cutaneous Syndrome?

-affects puppies

-presents with pustules, vesicles, and crusts on face and ears

-associated with cellulitis and lymphadenopathy

-puppies appear sick

look-alike diseases:

what is Juvenile Cellulitis?

-diagnosed based on breed and young age

-requires skin and muscle biopsies

-EMG shows abnormal spike potentials

look-alike diseases:

what is Dermatomyositis?

-immune-mediated reaction with toxic effects

-keratinocyte death (apoptosis)

-severe generalized lesions with target lesions

*cutaneous drug reactions

what is Erythema Multiforme?

-possibly a more severe form of erythema multiforme

-characterized by full-thickness necrosis

-usually affects dorsal areas

*cutaneous drug reactions

what is Toxic Epidermal Necrolysis?