Thyroid Disease Flashcards
what is the most over diagnosed thing ever in dogs
hypothyroidism
what are the 2 kinds of primary hyppthyroidism?
acquired : lymphocytic thyroiditis, immune mediated destruction. Heritable in beagke and borozi. can also be idiopathic thyroid atrophy
congenital: super rare, associated with cretinism, happens in fox terriers and rat terriers
which breeds tend to get hypothyroidism the most?
golden retrievers, doberman pinschers, beagles, and many many more
hypothyroidism is often in ______ dogs
younger
your friend calls you and says that they think their dog has hypothyroidism. You have neveer actually seen this dog before, so you suggest to your friend to bring it in to you. what clinical signs would you look for to increase your suspicions of hypothyroidism?
dermatologic/skin issues: alopecia, dry dull hair coat, change in coat color, poor hair regrowth, puppy haircoat
could also be: seborrhea, hyperkeratosis, recurrent superficial pyoderma, recurrent otitis externa
others: lethargy, obesity with same or decreased appetite, neurologic signs, myopathies
In an obese dog with subtle dermatologic issues over the last few months that now has facial nerve paralysis and signs of peripheral vestibular disease, what disease are you thinking?
hypothyroidism
corneal lipid deposits are consistent with what disease
hypothyroidism
besides hypothyroidism, what other differentials do you have for peripheral vestibular disease?
otitis media/interna
geriatric idiopathic peripheral vesitbular disease
your friend brings in their dog, Jake, that they think has hypothyroidism and you take a look. He does have some thin hair on his flank, bilateral, and he is very obese. He has also has a catheter shaved spot on his front left leg from a dental procedure he had months ago and the hair hasn’t grown back. If this dog does have hypothyroidism, what would you expect on a CBC chem?
possibly a mild non regenerative anemia
a fasting hypercholesterolemia
hypertriglyceridememia
high ALP and ALT
Jake the dog has high cholesterol, high triglycerides, and a slight non regenerative anemia. What is/are the next test(s) you want to do for him to confirm hypothyroidism? Are there pros and cons for each test?
total T4: this is a good first screening test that is sensitive but not specific (if normal it’s unlikely to be), if this is low, it does not mean they are for sure hypothyroid
free T4: a more complicated test, not affected by antibodies of protein concentrations, a really good single test but VERY EXPENSIVE and takes a few days to come back
TSH: not sensitive on it’s own, would need a total or free T4 test first
why would you want to do an anti-thyroid antibody test?
some dogs like beagles have an immune mediated thyroiditis can have clinical signs of hypothyroidism but normal total T4 because it’s counting the antibodies as T4, so in this case you may want to measure these antibodies
briefly describe sensitivity vs specificity
sensitivity is a big fishing net: you’re wanting to CATCH EVERYTHING! You’re unlikely to miss something but you also might catch some unwanted stuff. total T4 test is like this, it’s useful for ruling OUT
specificity is a harpoon: you go hunting for a specific single fish. You will miss other fish of the same kind but the fish you do catch will for sure be the one you want
what is euthyroid sick syndrome?
when theres a disease or illness not associated with thyroid but affects the thyroid hormone concentrations
true or false: a lot of things affect T4 concentrations daily
true! daily variation, small breed and obese dogs can have higher amounts, greyhounds can have lower, certain meds like steroids can cause low T4, systemic illness elsewhere
You run a total T4 on jake and it’s low. What are your next steps?
run either a TSH or a free T4
if TSH is high: confirmed hypothyroid
if TSH is low: unlikely hypo, but could run a free T4
if FT4 is low: confirmed hypothyroid
if FT4 is normal: unlikely hypo
