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What electrolyte imbalance in hallmark of Addison's?
What is most common neoplasm in adrenal medulla of animals? what species are common? functional?
- pheochromocytoma (dogs/cattle)
- rarely functional
What is a nonneoplastic noninflammatory enlargement of thyroid gland due to increased TSH bc of low serum levels of T3/T4?
What type of diets cause goiters?
- iodine deficient diet
- excess dietary iodide
- goitrogenic compounds (brassica and cruciferae plants like cabbage)
What else can cause goiters besides dietary sources?
genetic enzyme defects in hormone synthesis
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
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)
Multifocal nodular hyperplasia of thyroid is nonfunctional in most animals except which species? What does it cause in this species?
cats --> hyperthyroidism
What type of goiter is autosomal recessive and results in genetic impairment of thyroglobin synthesis so T4 levels remain low?
Congenital dyshormogenetic goiter
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)
What neoplasia of thyroid is freely movable under skin and may be functional? Who is it more common in?
- follicular cell adenoma
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)
Why do aged cats get hyperthyroidism?
adenomas and multinodular hyperplasia (functional proliferative lesions)
What cardiac abnormality is seen in conjunction with hyperthyroidism in cats?
secondary hypertrophic cardiomyopathy
Hypothyroidsm in dogs and horses is due to what?
- lymphocytic thyroiditis
- follicular cell neoplasms
- chronic pituitary lesions --> inhibit release of TSH
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
Hyperplasia of thyroid C cells (parafollicular cells) can be diffuse or nodular. Which lacks a capsule?
nodular lacks capsule
What leads cows to develop parturient paresis (milk fever)? Is this a case of hypo- or hyper- parathyroidism?
- fed high Ca diet
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
What are mechanisms of pseudohyperparathyroidism, a type of paraneoplastic syndrome?
- humoral hypercalcemia of malignancy
- hyperCa induced by bone neoplasia
- hematologic malignancy (LSA, mult.myeloma)
Which form of DM are dogs more likely to get? Cats?
- dogs: type I (beta cell destruction)
- cats: type II (insulin resistance)
What is pathogenesis for type II diabetes in cats?
- amyloidosis of islets
- severe vacuolation of beta cells
what are clinical signs and lesions associated with DM?
- hyperglycemia/glucosuria/glycogen nephrosis
- PU/PD/polyphagia with wt loss & weakness
- recurrent infection
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
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)
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