Companion Animals: Advanced Disease Topics Dr. N. Matthew Ellinwood, D.V.M., Ph.D. April 4, 2012 I OWA S TATE U NIVERSITY C OLLEGE OF A GRICULTURE AND L IFE S CIENCES

Disease Immune mediated disease Dermatology Endocrine disease

Immune Mediated Disease Disease with an immune system component –Versus Autoimmune disease –A specific class of immune mediated disease

Immune System Non-specific immune response –Not associated with a memory response –Not associated with a specific recognition of antigens –Can include non-immune cells –Example Type I interferon Fast (within a few hours) “Generic” activity against many agents (viruses)

Specific Immune Response (Adaptive Immunity) Cell mediated Immunity –Cytotoxic response (cell killing response) –T cells Humoral immunity –Antibody response –B cells – plasma cells

Immune Responses Innate immune response participate in –Innate immunity –Adaptive immunity Ex: Complement system Ex: T-cells function in both cell mediated and humeral immunity

Tolerance Mechanism whereby immune response “learns” to distinuish self from non-self Thymic “education” Self reactive immune cells are targeted for physical or functional elimination –Clonal elimination –Anergy –Immunoregulation

Immune Mediated Conditions Auto immune disease –Lupus Atopy/Allergy

Lupus Systemic lupus erythematosus Multisystem connective tissue disease Autoantibodies –Antinuclear antibodies –Double stranded DNA Unknown triggers but enviornmental triggers suspected. Genetic predisposition Females affected more commonly

Atopy/Allergy Immune mediated condition involving IgE Causes intense puritis in dogs and cats Animal equivalent to “hay fever”

Causes Flea bite sensitivity Food allergy Environmental allergies –house dust mites, house dust, human dander, feathers, molds, and pollens from trees, weeds, and grasses

Diagnosis Food trials –Restricted food source as trial Extreme restriction necessary Can be used as a maintenance Skin testing –Desensitization Vaccination to induce IgG that will out bind IgE and hence eliminate allergic response.

Food Allergy versus Food Intolerance Allergy is a specific immune mediated IgE based response to a food antigen Gluten sensitivity –Food intolerance that is not allergy based

Additional Immune Mediated Disease Hemolytic anemia –American cocker spanials Immune mediated hypothyroidism –Canine condition

Endocrine Disorders Thyroid disorder –Hypothyroidism Aquired: Canine Congenital: Feline > Canine (rare) Treatments –Hyperthyroidism Feline Aquired Age related Treatments

Adrenal Disease (Canine usually) Too little of steroid function –Addison’s Disease –Signs; muscle weakness, neuropathy, low blood sugar, skin darkening, low heart rate –Genetic predisposition –Managed medically by replacing adrenal steroids Glucocorticoids Mineralocorticoids

Adrenal Disease Too much steroid function –Cushing’s Disease –Signs; weight gain/redistribution, thinning hair, pendulous abdomen, muscle wasting, PU/PD –Imitates steroid immunosuppression sysmptoms –Genetic predisposition –If adrenal in origin can selectively target adrenal steroid production for destruction –If create an Addisonian dog, can supplement

Endocrine Diseases Alternative mechanisms Cancer Pancreatic disease –Diabetes –Insulinoma Special cases –Ferrets