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Companion Animals:
Advanced Disease Topics
Dr. N. Matthew Ellinwood, D.V.M., Ph.D.
April 4, 2012
IOWA STATE UNIVERSITY
COLLEGE OF AGRICULTURE AND LIFE SCIENCES
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