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57 Cards in this Set
- Front
- Back
Describe the pathogenesis of atopic dermatitis.
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Atopic dermatitis is “strange disease” and is a familial predisposition to the development of IgE antibodies and clinical allergy to environmental antigens
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Describe the lesions and distribution pattern of atopic dermatitis
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Lesions:
-Erythema -Alopecia -Papules -Excoriations -Hypepigmentation -Lichenification Distribution: -Muzzle -Periocular -Axillae -Feet -Flexor surfaces of elbows and tarsus -Extensor surface of carpus -Lesions may become generalized in chronic cases |
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What are the advantages and disadvantages of RAST?
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Advantages
-Very specific Disadvantages -Poor reproducibility -Poor specificity for IgE -Many false positives -Great seasonal variability |
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What are the advantages and disadvantages of IDST?
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Advantages
-Gold standard for determining allergens -Shows whether or not an allergen is capable of producing skin lesions in the tested patient -Immediate results Disadvantages -Owners refuse clipping of fur -If skin does not respond to the histamine, it won’t respond to injected allergens -No access to the test |
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How do you interpret a negative IDST?
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-Patient not allergic to reaction
-SQ injection given -Insufficient antigen -Concurrent drugs blocked the skin test (this is why they must be off drugs before testing) -Prolonged allergy (exhaustion of IgE levels) |
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How do you interpret a positive IDST?
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-Patient allergic to antige
-Patient allergic to the cross reacting antigen -Irritants -Bacterial or fungal contamination -Antigen contains histamine -Too large volume injected |
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What are the advantages and disadvantages of using corticosteroids for the treatment of atopic dermatitis?
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Advantages
-Very effective at decreasing skin inflammation and itching Disadvantages -Many side effects (PUPD, panting, weight gain, increased risk of infection, ect.) -Use only if other therapies are not feasible |
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What are the advantages and disadvantages of using cyclosporine for the treatment of atopic dermatitis?
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Advantages
-Effective in severe allergy cases for decreasing skin inflammation and itching -Suppresses T cells and decreases IgE production -Decreases production of cytokine Disadvantages -Side effects (GI, renal, hepatic, bone marrow) -Costly |
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What are the advantages and disadvantages of using hyposensitization (immunotherapy) for the treatment of atopic dermatitis?
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Advantages
-Increases T suppressor cell activity, w/ gradual decrease in IgE -Blocks antibodies -Decreases number of mast cells and/or decreases histamine release from mast cells Disadvantages -May req. 9 months or longer to obtain maximal effectiveness -25-50% chance of not working or needed additional treatment |
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Discuss client education of the treatment of atopic dermatitis.
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-Must communicate that the animal is a walking dust mite and they must be bathed frequently
-Also, if animal is allergic to material in house or what owner wears, significant changes must be made -Owner must be committed to working w/ the disease or the animal will suffer for their entire life |
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Describe the MOA of glucocorticoids in treatment of allergy.
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-Glucocorticoids block Cox 1 and 2 as well as phospholipase A (which is needed to make Prostaglandins)
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Describe the benefits of antihistamines in cats and dogs
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-Antihistamines are a good preventative drug, just not great for treatment
-Block H1 and H2 receptors -Stabilize mast cells -Few side effects |
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Describe the physiological basis of alternate day steroid administration.
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-Alternate day therapy is an attempt to control the animals atopy while giving them less drug. This will decrease the potential for side effects and resistance.
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Are lamb and rice nonallergenic?
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-NO- lamb and rice are not non-allergenic (many animals are, in fact, allergic to lamb)
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Why are lamb and rice chosen for some hypoallergenic diet trials?
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-Lamb and rice are chosen however for some hypoallergenic diets b/c lamb is a novel protein and if the animal has never tried lamb it might be worth a try. Rice is added in as the carbohydrate source
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Devise a restrictive diet trial for a cat or dog for which you have been presented with a list of its past diet.
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HOME COOKED DIETS
-Choose a protein source that the animal has never been exposed to (lamb, fish, venison, rabbit, tofu, pinto beans) -Choose a carbohydrate source (brown rice, white rice, potatoe, green peas) -Mix the two as a 1 part protein : 3-4 part carbo STORE DIETS -Again look for a protein source the animal hasn't tried (Hill D/D, Z/D or Purina HA) |
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What are the DDX of a cat w/ pruritis on its head and neck.
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-Food allergy
-Ear mites -Notoedres -Flea allergy dermatitis |
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How can you differentiate allergic contact dermatitis from an irritant contact dermatitis?
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Allergic Contact dermatitis:
-An inflammatory skin disease caused by a delayed (cell-mediated) response to an antigen or hapten. Requires repeated or continuous exposure to the substance Irritant Contact Dermatitis: -An inflammatory skin disease which occurs within minutes of contact w/ irritating substance |
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Outline measures that can be used to minimize an animals exposure to housedust mites.
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-Remove carpets, blinds, plants, upholstered furniture, cluster
-Use plastic encasings for mattresses, boxsprings, pillow -There are some products to kill HDM |
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Describe the clinical presentation of erythema multiforme.
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-Erythematous macules and papules that spread
-Urticarial plaques that last for many days -Vescilces/bullae -Any combo of these |
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Describe the clinical presentation of Toxic Epidermal Necrolysis.
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-Vesicles/bullae
-Necrosis -Systemically ill -Entire epidermis of the lesion can be necrotic and slough off |
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What are the usual causes of Toxic Epidermal Necrolysis.
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-Drugs***
-Toxins -Infections -Neoplasms |
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What are the usual causes of Erythema Multiforme.
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-Drug allergies ***
-Trimethoprim/sulfa -Cephalexin |
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What are some etiologies for feline miliary dermatitis?
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-Ectoparasites
-Dermatophytes -Allergies -Nutritional -Bacterial -Contact -Autoimmune -Idiopathic |
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What is a diagnostic plnn for feline miliary dermatitis?
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-Examine for parasites
-Woods light -DTM culture |
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What is the clinical presentation of an indolent ulcer?
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-Ulcers on upper lip or orally
-Female cats (5-6 yrs. Age) -No eosinophils |
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What is the clinical presentation of an eosinophilic plaque?
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-Well circumscribed, raised, ulcerative plaque
-Abdomen, back, legs, head, neck -Female cats (3yrs) -Eosinophilic and mast cell infiltration |
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What is the clinical presentation of a linear granuloma?
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-Linear tract on posterior aspect of hind limbs
-Severe cases can be seen in the oral cavity -Either sex (1-5yrs) -+/- Eosinophils |
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How would you identify an indolent ulcer?
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-Histopath
-Hyperplastic ulcerative dermatitis w/ PMN, plasma cells, mononuclear cell infiltrate -DDX -Squamos cell carcinoma and Fibrosarcoma |
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How would you identify an eosinophilic plaque?
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-Histopath
-Eosinophilic and Mast cell infiltrate -Workup -Biopsy -Flea control*** -Hypoallergenic diet -IDST |
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How would you identify a linear granuloma?
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-Histopath
-Necrobiosis of collagen w/ histiocytic and multinuclear giant cell infiltrate +/- eosinophils |
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How would you treat an indolent ulcer?
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-Identify and treat underlying cause
-Antibiotic trial -Clavamox or Tribissen -Systemic Corticosteriods -Pred -Depo-Medrol REFRACTORY OR RECURRENT: -CO2 laser -Radiation treatment -Cyrosurgery -Immuno-stimulants (Levamisole or Thiabendazole) |
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How would you treat an eosinophilic plaque?
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-Identify and treat underlying cause
-Elizabethan collar -Antibiotics -Corticosteriods |
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How would you treat a linear granuloma?
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-Observation
-Identify and treat underlying cause -Antibiotics -Corticosteriods -Immuno-stimulants |
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Describe the clinical presentation of feline plasma cell pododermatitis.
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-Non-painful swelling of footpads that may ulcerate
Clinical Pathology: -Hypergammaglobuinemia -Lymphocytosis -Neutrophillia |
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List the potential side effects of progesterone therapy.
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-Hyperglycemia (leading to DM)
-Acromegaly -Mammary hyperplasia (leading to neoplasia) -Pyometra -Infertility -Behavioral changes |
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What is cyclosporine? What is its MOA in the treatment of atopy?
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-Cyclosporine is an immuno-suppressive drug.
MOA: -Suppresses T helper cells -Decreases IgE production -Decreases production of cytokines -Overall decreases skin inflammation and itching |
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How is canine atopic dermatitis diagnosed?
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-Must have at least 3 of the Major Criteria:
-Pruritis -Typical morphology and distribution -Involves face, feet, legs -Seasonal or chronic dermatitis -Family or breed predisposition -Must have at least 3 of the Minor Criteria: -Onset of symptoms <3 years of age -Facial erythema and chelilitis (inflammation around lips) -Bilateral conjunctivitis -Superficial staph pyoderma -Increased antigen specific-IgE -Increased antigen-specific IgG4 -Immediate skin test reactivity |
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Is it possible to cure an atopic dog?
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-No, just medically manage dog
-However, those animals treated w/ hyposensitization 25% may develop complete remission |
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What are the major causes of treatment failures in canine atopic dermatitis?
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-Client compliance
-Don’t remove all possible environmental contaminants -Don’t dose animals med’s correctly |
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What is the “flare factor” relating to atopy?
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-The reaction that occurs in response to certain allergen
-Fleas are a big flare factor |
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Why is it important for owners to understand the concepts of summation of effects and pruritic threshold.
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Summation of effects:
-It is the culmination of all things that can lead to the animals atopy problem -If the owner can understand that there are a whole host of things that play a role in their animals atopy then maybe then can understand why treatment is so difficult and why they must play an active role in the process. Pruritic Threshold: -The level above which the animal will experience atopy -Many factors contribute the animal exceeding the threshold -For example: If fleas are the underlying cause and they are never treated, then the animal can never drop below the pruritic threshold |
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What are the causes and pathogenesis of food allergies?
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Causes:
-Sudden reaction to a food source (usually one protein) that triggers an immunological response -a lot are not IgE mediated Patho: -Food allergies can be either a Type I, III, IV hypersensitivity reaction |
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What is the best way to diagnose a food allergy
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-The best way to diagnose food allergy is to do a restrictive diet trial
-Symptoms should subside off food (w/in at least 7 days) -Challenges should be reproducible (onset, duration, clinical features) -Symptoms should be gone after each withdrawal |
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What is an allergen? Antigen?
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Allergen: an antigen that stimulates an IgE response (ex. Pollens, dust, animal dander, feathers)
Antigen: a substance that elicits an antibody response |
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How does contact hypersensitivity manifest in animals?
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-Lesions usually occur in non-haired areas (feet, ears, ventrum, scrotum, chin, neck)
-Pruritis may be the only sign -Severe cases: erythema, vesicles, ulcers, crusts, self-trauma |
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What are the differences between atopy and contact dermatitis?
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Atopy:
-A familial predisposition to the development of IgE antibodies and clinical allergy to environmental allergens. Contact dermatitis: -Can either be allergic or irritant Allergic Contact dermatitis: -An inflammatory skin disease caused by a delayed (cell-mediated) response to an antigen or hepten. Requires repeated or continuous exposure to the substance Irritant Contact Dermatitis: -An inflammatory skin disease which occurs within minutes of contact w/ irritating substance |
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What are the common causes of contact hypersensitivity in dogs?
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-Plant or plant pollen
-Molds -Meds (neomycin, tetracain, shampoos, insecticides) -Floor wax -Polish or cleaners -Dyes in rugs -Carpets, blankets -Rubber and plastic products |
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Will anti-histamine creams lessen inflammation in animals w/ contact hypersensitivity? What other treatments would you recommend?
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-No anti-histamine are good are prevention, not a treatment once the animal is inflamed
Other treatments: -Remove offending agent -Bath after exposure -Topical drying agents (Domeboro) -Topical or systemic corticosteroids -Pentoxiphylline -Topical tacrolimus |
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What is miliary dermatitis?
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-Variable pruritic papulocrustous eruption occurring over dorsum, head, and neck
-Millet seed lesions = hemorrhagic crusts |
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What approach would you follow in treating a cat w/ miliary dermatitis?
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1. Flea control (if they respond, may be the only treatment)
2. Hypoallergenic diets 3. Skin biopsy -Allergic = IDST -Bacterial = C/S and TX -Fungal = DTM and TX -Pemphigus = DFA, TX -Non-specific = Pred -No response = Short term megesterol acetate |
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What is erythema multiforme?
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it is an allergy, usually drug associated
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How do you diagnose erythema multiforme?
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-Physical Exam
-Clinical signs |
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How do you treat erythema multiforme?
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-Removal of drug
-Possible corticosteroids?? |
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What is toxic epidermal necrolysis?
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full thickness coagulation necrosis of epidermis
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How do you diagnose toxic epidermal necrolysis?
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-Histopath
-full thickness coagulation necrosis of epidermis |
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How do you treat toxic epidermal necrolysis?
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-Correct underlying cause
-Supportive care -Pred (be careful there can be a high risk of sepsis) |