Canine Flash Notes - Hypothyroidism

Question 1

hypothyroidism is a common endocrine disease of what animal?

Answer 1

dogs

Question 2

what is the classic case presentation of a dog with hypothyroidism?

Answer 2

any middle aged dog - no gender bias

Question 3

what clinical signs are often seen with hypothyroidism?

Answer 3

weight gain without increased appetite, dullness, lethargy, tragic facial expression, & bilateral non-pruritic alopecia

Question 4

what is the diagnostic test of choice for hypothyroidism?

Answer 4

serum concentrations of total t4, free t4, & tsh

Question 5

how sensitive is total t4?

Answer 5

90%

Question 6

why is a free t4 useful?

Answer 6

useful in distinguishing hypothyroidism from euthyroid sick syndrome

Question 7

what does a normal or increased TSH indicate?

Answer 7

need to evaluate in light of t4, cholesterol, etc - hypothyroid

Question 8

what does a normal or low TSH indicate?

Answer 8

sick euthyroid, early hypothyroid, or pituitary issue (rare)

Question 9

what breeds may have lower thyroid levels?

Answer 9

greyhounds, scottish deerhounds, & alaskan sled dogs

Question 10

what drugs can cause lower thyroid levels?

Answer 10

KBr, prednisone, phenobarbitol, clomipramine, propanolol, & some NSAIDS

Question 11

what is an excellent screening test for hypothyroidism?

Answer 11

fasting hypercholesterolemia - seen in 80% of cases

Question 12

what is the gold standard test for diagnosing hypothyroidism?

Answer 12

TSH stimulation test - gold standard but very expensive

Question 13

what is the treatment used for hypothyroidism?

Answer 13

levothyroxine sodium - using the brand name as bioavailability varies in generics

Question 14

what is the prognosis for primary hypothyroidism?

Answer 14

good to excellent

Question 15

T/F: when measuring TSH, it must be the species specific assay

Answer 15

TRUE