|Photography by Nottingham Vet School on Flickr|
I don't know for sure what links these symptoms. But it interesting to try and find out. It would have been nice if the vet school had told us so I could check.
My research indicates that one condition links polydipsia and alopecia. The third symptom, redness of the skin may be due to overgrooming causing the alopecia.
Hyperthyroidism may cause an increased thirst. It is almost always linked with cancer, usually a benign adenoma (a tumor of glandular origin).
About 33% of all cats with hyperthyroidism show "areas of alopecia. The hair is pulled out easily".
The increase in thyroid hormones may also cause an increase in appetite and activity. There may be weight loss and panting.
Accordingly, this black and white cat might have hyperthyroidism.
Source: Book 1 on this page.