Understanding Feline Hyperthyroidism
📝 Summary
Feline hyperthyroidism is excess thyroid hormone, common in senior cats and usually benign nodules. Signs include weight loss with ravenous appetite, restlessness, and coat changes; suspect it in any sick cat over ten. Treat by surgery, daily medication, or radioiodine, and prevent via diet and regular senior checkups.
1 The Disease
Hyperthyroidism means excess thyroid hormone (T4, T3), a common endocrine disease in older cats, usually from a thyroid tumor driving high metabolism.
Cause: too much thyroid hormone from the gland, mostly benign single or double nodules felt on the lower neck; cancerous thyroid is under 5 percent.
Signs: weight loss with overeating, anxiety, and over-excitement; coat changes like patchy hair loss and dull, matted fur; more urination, thirst, vomiting, diarrhea; some cats turn aggressive, which clears after treatment. A few show lethargy, weakness, and anorexia instead. Because effects are multi-system, suspect it in any sick cat over ten.
2 Treatment and Prevention
Three options: thyroidectomy, daily anti-thyroid medication (suppresses but needs lifelong dosing), or radioiodine; surgery and radioiodine aim for a permanent cure. Choice depends on age, kidney function, severity, nodule type and side, and availability.
Prevention: epidemiology links risk to too much or too little iodine and substances like soy isoflavones, bisphenol A from cans, and flame retardants from litter and beds, so avoid them and feed quality, nutritious food. Hyperthyroidism is common in seniors, so check regularly; cats with heart disease (especially HCM) need monitoring to spare the heart.
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