Pathophysiology of the Thyroid Gland Flashcards
what is the primary effect of thyroid hormone?
increase metabolic rate and promote fetal growth and development
what does thyroid hormone do with erythropoiesis?
increases it
increases erythropoietin secretion
facilitates response to erythropoietin
what is the thyroglossal duct?
tract that thyroid tissues migrates down from the floor of the pharynx
failure of the thyroglossal duct to involute leads to _________________________
a thyroglossal cyst
who is congenital hypothyroidism especially common in?
small ruminants
what is the most common thyroid disease in horses and small ruminants?
congenital hypothyroidism
what type of goiter does congenital hypothyroidism cause?
diffuse hyperplastic goiter
nonneoplastic
noninflammatory
______________________ of a pregnant animal can cause congenital goiter
iodine deficiency
can iodine toxicity cause congenital hypothyroidism?
yes
what do high nitrate levels cause with the thyroid?
nonfunctional hypertrophy of the thyroid: inhibits ability to utilize available iodide
how might a pregnant mare get nitrate toxicity?
consumes plants or contaminated water
common grasses accumulate nitrate
nitrates accumulate with _________________________________
fertilization
drought conditions
some herbicides
are goitrogenic substances more likely to affect the fetus or the mother?
fetus
what does familial dyshormonogenetic goiter cause?
enzyme defect in thyroid hormone synthesis: impaired biosynthesis of thyroglobulin
what are the possible findings with congenital hypothyroidism?
rough haircoat, alopecia
hypothermia
weakness
stillbirths
may die within a few days of birth
true/false: congenital hypothyroidism can also present with CNS lesions
true
poor suckling, incoordination, poor righting reflexes
___________ is the most common thyroid disease of birds
goiter
what species of birds are goiters seen in predominantly?
pigeons
canaries
cockatiels
budgerigars (budgies)
what are some causes of goiter in birds?
iodine-deficient seed diet
goitrogenic substances
acute septicemia
exposure to organophosphates or chlorinated bisphenols
what are the clinical signs of goiter in birds often from?
mass effect: pressure, fluid buildup
hormone deficiency
what clinical signs are associated with hormone deficiency from goiter in birds?
immunodeficiency
depression and lethargy
abnormal skin and feathers
reproductive problems
what are the most common causes of canine hypothyroidism?
lymphocytic thyroiditis
idiopathic thyroid atrophy
what happens in lymphocytic thyroiditis?
slowly progressive destruction and fibrosis
what happens in idiopathic thyroid atrophy?
thyroid replaces with adipose tissue
degenerate follicular cells in colloid
no inflammation, antibody tests negative