We have one cat with hyperthyroidism , another with the same thyroid disease complicated by kidney issues, and a third with severe respiratory issues we cannot solve. I fear cancer is the root of her issues, and likely to end her life soon. I have lost cats to cancer in past years and won’t treat them because the treatment is brutal (I did treat one, lost her, and said never again). All the cats with health problems are old ladies who have lived with us for a dozen or more years.