I noticed some redness in Sadie's eyes, which is typical of allergy season. I tried the typical tricks (eye rinse, Benadryl), but only one eye reduced in redness. With a closer look, I noticed a small discoloration to her iris. With one stop at our regular vet, and a second at the veterinary ophthalmologist, I learned that she had a tumor inside her eyeball.

The choice was simple: it's a quick surgery to remove her eyeball, which was likely to have contained the cancer (which biopsy revealed to be melanoma). My poor girl... although she doesn't seem to have noticed. Distortion of the lens meant that she was already blind in that eye, and its removal likely eased some discomfort. In hindsight, I recall her rubbing her eye with her paw, and being startled by my outstretched hand reaching to pet her... like she didn't see it coming.