In cats over 10, 'acting energetic again' and 'always hungry but getting thinner' can be signs of hyperthyroidism — not a second wind. This common senior cat disease is treatable when caught early.
An overactive thyroid drives metabolism into overdrive. Your cat may seem constantly starving no matter how much it eats.
All that food is burned off by a runaway metabolism. Muscle wasting follows, even when appetite is strong.
A senior cat racing around at night or vocalizing constantly may not be 'feeling young again' — it may be sick.
Thyroid hormones overstimulate the heart. Over time this can cause hypertrophic cardiomyopathy (heart disease).
Accelerated gut motility leads to vomiting and loose stools.
Metabolic acceleration combined with kidney stress drives up fluid intake and urine output.
Hyperthyroidism is the most common endocrine disorder in senior cats, caused by excess thyroid hormone production — usually from a benign thyroid tumor (adenoma). It affects cats of all breeds but is most prevalent over 10 years of age.
What makes it easy to miss is that the early signs look like vitality. An owner who sees their older cat eating enthusiastically and being active may not suspect illness until significant weight loss occurs.
Treatment options include daily medication (methimazole), a low-iodine prescription diet, surgical removal of the thyroid gland, and radioactive iodine therapy. Medication is the most common choice and costs roughly $30–$80/month. All options are effective when started early.
CatsMe lets you track your senior cat's weight and behavior patterns daily. 'Eating more but getting thinner' and 'unusually active at night' are exactly the kinds of trends CatsMe helps you document — and share with your vet at your next visit.
Get Started FreeYes — radioactive iodine therapy and surgery are considered curative for most cats. Daily medication controls symptoms effectively but must be continued long-term. All options carry a good prognosis when diagnosed early.
A thyroid hormone blood test costs approximately $50–$150. Daily medication runs $30–$80 per month plus regular bloodwork monitoring. Radioactive iodine therapy is a one-time cure but costs $1,000–$2,500.
Hyperthyroidism artificially boosts blood flow to the kidneys, which can mask underlying CKD. When the thyroid is treated, kidney values may worsen, revealing the hidden kidney disease. Monitoring both simultaneously is essential.