L2. Feline Hyperthyroidism Flashcards
Feline Hyperthryroidism
Primary endocrinopathy
Thyroid gland is the problem
Thyroid tumors:
Benign
70-75% affected cats
Both thyroid lobes involved
Thyroid Tumors
Malignant
1-3% cases
Hyperthyroidism
Patient History
Middle-aged and older
weight loss
polyphagia
Unkempt hair coat
PU/PD
vomiting
hyperactivity
Diarrhea
Heat intolerance
Behavior changes
Cardiac failure / disease
Thyroid “storm”
Hyperthyroidism
Physical Examination
Thyroid nodules (goiter)
Abnormal BCS
Fractious/hyperactivity/ behavioral abnormalitlites
Abnormal heart sounds - tachycardia, murmur, Arrhythmia
Overgrown nails, sunken eyes
Systolic hypertension
Hyperthyroidism
Laboratory Abnormalities
CBC
Unremarable, non-specific changes
Hyperthyroidism
Laboratory Abnormalities
Chemistry
No changes are diagnositc or pathonimonic
Hyperglycemia
Azotemia
Symmetric dimethylarginine (SDMA)
Elevated ALT/ALP
Hyperthyroidism
Interpretiation
Total T4
Free T4
TSH
Total T4 - high
Free T4 - High
TSH - low
“MASKED” Chronic Kidney Disease
Abnormal kidney anatomy:
Abdominal palpation
Imaging findings
Abnormal Kidney Function
Signs of CKD - overlap with Hyperthryroidism
Urea and Creatinine values may be misleading
Reduced urine concentration
SDMA - diagnositc usefulness is currently unclear
Abnormalities persist after euthryroidism restored
Changes consistent with CKD do not resolve or worsen after treatment for Hyperthyroid
Hyperthyroid
Cardiac Evaluation
May develop reversible hypertrophic cardiomyopathy
All cardiac changes resolve after effective anti-thyroid treatment
Cardiac Signs:
Tachycardia
murmur
respiratory distress
tachypnea or panting
muffled heart sounds
Hyperthryroidism
Treatment Options
Medical Management
Radioactive Iodine
Dietary Therapy
Surgical Thyroidectomy
Hyperthyroidism:
Medical Management
Methimazole
Oral and transdermal options
Prevents thyroid hormone production
LIFE LONG THERAPY
Hyperthyroidism
Radioactive Iodine
Specifically targets overactive thyroid tissue → active tissue = abnormal tissue
emits beta radiation
>95% cure rate with single dose
Expensive, and requires special permits to administer
Hyperthryroidism
Surgical Thyroidectomy
NOT COMMONLY DONE
Hyperthyroidism
Prognosis
CURABLE DISEASE
Prognosis depends on:
physical condition at diagnosis
simultaneous disease present
Benign vs.malignant
Treatemnt options available
