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What electrolyte imbalance in hallmark of Addison's?
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What is most common neoplasm in adrenal medulla of animals? what species are common? functional?
- pheochromocytoma (dogs/cattle)
- rarely functional
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What is a nonneoplastic noninflammatory enlargement of thyroid gland due to increased TSH bc of low serum levels of T3/T4?
goiter
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What type of diets cause goiters?
- iodine deficient diet
- excess dietary iodide
- goitrogenic compounds (brassica and cruciferae plants like cabbage)
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What else can cause goiters besides dietary sources?
genetic enzyme defects in hormone synthesis
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What is general mechanism for goiter formation?
inadequate thyroxine synthesis --> decr. T4/T3 blood levels --> secretes more TSH --> hypertrophy and hyperplasia of thyroid follicular cells --> goiter
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What represents the involutionary phase of diffuse hyperplastic goiter seen in young and adult animals once sufficient iodide is added to diet?
colloid goiter (decreased endocytosis of colloid from lumen)
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Multifocal nodular hyperplasia of thyroid is nonfunctional in most animals except which species? What does it cause in this species?
cats --> hyperthyroidism
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What type of goiter is autosomal recessive and results in genetic impairment of thyroglobin synthesis so T4 levels remain low?
Congenital dyshormogenetic goiter
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What species are more likely to get congenital dyshormonogenetic goiters? How long do they survive?
- sheep (Corriedale, Dorset horn, Romney breeds)
- dwarf goats
- Afrikander cattle
- most die shortly after birth (delayed growth, myxedema, sluggish)
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What neoplasia of thyroid is freely movable under skin and may be functional? Who is it more common in?
- follicular cell adenoma
- cats
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What thyroid neoplasia is firm and palpable in the neck and may cause tracheal compression as it is "fixed" in position? Who is this more common in?
- follicular cell carcinoma (often metastasize to lungs)
- dogs (beagle, boxer, GR)
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Why do aged cats get hyperthyroidism?
adenomas and multinodular hyperplasia (functional proliferative lesions)
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What cardiac abnormality is seen in conjunction with hyperthyroidism in cats?
secondary hypertrophic cardiomyopathy
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Hypothyroidsm in dogs and horses is due to what?
- idiopathic
- lymphocytic thyroiditis
- follicular cell neoplasms
- chronic pituitary lesions --> inhibit release of TSH
- goiter
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What clinical signs are associated w/hypOthyroidism? (consider metabolism, skin, reproduction, vessels)
- reduced metabolic rate
- hyperkeratosis/bilateral symmetric alopecia/hyperpigment/myxedema
- repro abnormality
- low T3/T4
- hypercholesterolemia --> artherosclerosis
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Hyperplasia of thyroid C cells (parafollicular cells) can be diffuse or nodular. Which lacks a capsule?
nodular lacks capsule
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What leads cows to develop parturient paresis (milk fever)? Is this a case of hypo- or hyper- parathyroidism?
- fed high Ca diet
- hypOparathyroidism
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What is main source of primary hyperparathyroidism? Secondary? which is more common?
- 1= adenoma in older dogs, usually functional (rarely carcinoma)
- 2(more common) = nutritional imbalance (all spp.) or renal dz (dog/cat); both due to hi P: low Ca
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What are mechanisms of pseudohyperparathyroidism, a type of paraneoplastic syndrome?
- humoral hypercalcemia of malignancy
- hyperCa induced by bone neoplasia
- hematologic malignancy (LSA, mult.myeloma)
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Which form of DM are dogs more likely to get? Cats?
- dogs: type I (beta cell destruction)
- cats: type II (insulin resistance)
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What is pathogenesis for type II diabetes in cats?
- amyloidosis of islets
- severe vacuolation of beta cells
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what are clinical signs and lesions associated with DM?
- hyperglycemia/glucosuria/glycogen nephrosis
- PU/PD/polyphagia with wt loss & weakness
- cataracts
- hepatomegaly
- recurrent infection
- microangiopathy
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What is common cause of heart base tumor that should be differentiated from tumor of ectopic thyroid? Functional?
- aortic body adenoma/carcinoma (more common than carotid body tumor)
- usually not functional but cause heart failure due to space occupancy
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What neoplasia arises near bifurcation of common carotid artery in cranial cervical area?
carotid body adenoma/carcinoma (slow growing but interferes with swallowing and blood flow)
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What type of adenoma/carcinoma accounts for 5-10% of "heart base" neoplasia in dogs? How can you ddx these from other heart base neoplasia?
- heart base neoplasia derived from ectopic thyroid gland tissue
- ectopic cells are smaller w/eosin. cytoplasm
- ectopic rarely have giant cells and stroma not prominent
- ectopic has follicular/colloid structure
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