Feline hyperthyroidism Flashcards
Describe the clinical signs of hyperthyroidism
Goiter
Aggressiveness
increased appetite
hyperactivity
weight loss
Describe the structure of the thyroid
consists of secretory parts called follicles filled with hormones-storing colloid
what do 98% of hyperthyroid cats have
a palpable goitre
how does hyperthyroidism cause the heart to have a HCM appearance
increased thyroid hormone
increases the response to the SNS, this causes vasoconstriction
LV hypertrophy occurs due to increased catecholamines
How can we check for systemic hypertension on clinical exam
check the eyes and take a blood pressure reading
Describe a thyroid crisis
A sudden increase in the output of thyroxine and resultant extreme elevation of all body processes
e.g. >300bpm, resp distres, sudden blindness
how to test for hyperthyroidism in cats
haematology
biochem
urinalysis
Total T4 and free T4 are the best ways to test specific thyroid function
why can cats with hypertension have urinary infections with no clinical signs
the cat may have PUPD and this will lead to hyposthenuric urine and masked UTI signs
what is commonly raised on biochemistry tests during hyperthyroidism
Liver enzymes
ALT and ALP
why can total T4 tests give false negatives
because the T4 levels fluctuate daily
If TT4 comes back normal and you only have a few clinical signs - how should you interret
doesn’t rule out hyperthyroidism-you need another test!
Describe euthyroid sick syndrome
abnormal findings on thyroid function tests that occur in the setting of a nonthyroidal illness, without preexisting hypothalamic-pituitary and thyroid gland dysfunction.
Normal thyroid but they are still ill
List 4 treatment options for feline hyperthyroidism
radioactive iodine (131I)
surgery
anti-thyroid medication
dietary management
Describe radioactive iodine treatment for hyperthyroidism
single S/C injection of radioactive iodine 131I
List 2 advantages and 2 disadvantage of the radioactive iodine treatment of hyperthyroidism
simple and effective
curative
requires licensing and hospitalisation facilities
cats become radioactive
for what two causes of hyperthyroidism would we specifically want to use radioactive iodine
ectopic tumours
locally invasive carcinomas
why would we possibly do a scintograph in cases of hyperthyroidism
to confirm hyperthyroid disgnosis and identify any ectopic tissue
when performing surgical thyroid removal, what do we have to be careful of
the parathyroid gland
why is using medical therapy for hyperthyroidism risky
you run the risk of malignant transformation
List 2 anti-thyroid drugs
carbimazole
methimazole
oral, transdermal ointment, liquid
what are some adverse reactions that can occur due to anti-thyroid medications
anorexia
vomiting
lethargy
face and neck excoriation
dyscrasia
hepatopathy
what type of diet can be given to cats with hyperthyroidism
restricted-iodine diet
what monitoring of a treated hyperthyroid cat should be done
clinical exam
BCS and nutritional assessment should be done regularly
Blood tests should be done depending on the treatment of choice
What issues can occur when treating hyperthyroidism with low-iodine diet
must be fed exclusively
questionable palatability
low protein content
Describe how you palpate the thyroid in cats
run your fingers up and down the trachea to feel for a goitre
Why is doing nothing not an option in hyperthyroidism
because the effect on organs can be deadly
why do cats have to be hospitalised for a week following radioactive iodine injection
in order to collect all faeces as it may be radioactive
