Not all dog cancers have the same symptoms. However, if we talk about skin cancer that could manifest as a progressive lump on dogs’ tail, we can expect several common symptoms. The first is swelling and redness. This is a common symptom for skin cancers and skin tumors. Depending on the size, swelling can be either big or small. Another symptom is inflammation. Many skin irregularities cause skin infections that result in inflammation, high temperature, or even fever. Progressed skin cancers also have these following symptoms: vomiting, nausea, lack of appetite, lack of energy, disinterest in any sort of activity, decreased mobility, stomachache, severe pain in the affected area, and many others. Unusual dog behavior, such as sleeping under the bed, or avoiding human company can indicate that something’s wrong with your puppy. Skin cancers, such as melanoma and mast cell tumors have deadly repercussions most of the time. They are hardly curable, and most dog owners subject their puppies to treatment in the later phases of these cancers.