Although cancer is less common in cats than in dogs, cats have the chance to contract cancer. Cat cancer symptoms are rather difficult to spot. Difficulty in breathing is a sign of cancer since some cancers are able to cause fluid in the lungs. However, this symptom may also indicate for condition other than cancers such as the usual bad air condition. Other symptoms include rough coat, weight loss and refusal to eat. However, to make sure if these are the indication of the presence of a cancer, it is always better to take the cat to the vet first.