Sign #3: Unexplained Weight Loss or Gain
If your cat is losing or gaining weight for no obvious reason, it’s a good idea to take them to the vet, especially if the weight change seems sudden. Weight gain or weight loss can indicate a thyroid condition in your cat, however the cause can be as severe as cancer.
In older cats some weight loss is normal as they lose muscle mass, but a significant loss can point to something serious. To put things into perspective, a cat gaining or losing a single pound is roughly comparable to a human gaining or losing 10 pounds.
Marked weight gain can result in obesity, which can lead to arthritis, tumors and a shorter lifespan. An obese cat can develop many of the same health problems that an obese human will, like diabetes or heart disease.