First, statistically, cancer TENDS to affect older dogs. So, more lumps and bumps on a young dog are benign than cancerous. One hallmark of a cancer is it worsens over time. Cancers you can see usually get bigger. A growth that stays very small for years is not likely to be a true cancer. Again, this is on average and is not a guarantee.

Some cancers are visible, while others are internal. The visible ones can be blackish (melanomas), purplish (hemangiosarcomas), fleshy, inflamed and red (histiocytomas), look like a non-healing open sore (squamous cell carcinomas), be firm, hard and deeply attached (fibrosarcomas), or have any appearance (mast cell tumor, the great imitator).

The internal ones are invisible, so we have to look for overall signs in the dog. When they are far along, cancers usually cause weight loss (cancer cachexia) without an obvious external reason. They often will cause less appetite. Many times dog owners will tell me they think their dog got tired of his or her food. They can cause low energy, where the dog will just lay around a lot.

Internal cancer signs also depend on where the cancer is happening. For example, a bone tumor (osteosarcoma) might cause a limp, or a bladder tumor (transitional cell carcinoma) might cause straining to urinate, blood in urine, or urinating small amounts frequently. A tumor found in the wall of the stomach might cause vomiting, and in the intestine, diarrhea.

Some cancers cause internal bleeding, like hemangiosarcoma of the spleen. This bleeding causes sudden weakness and wobbly legs. A nasal tumor like a squamous cell carcinoma might cause discharge or bleeding from a nostril, or sneezing that won’t go away. Lung cancers (bronchial adenocarcima) or tumors of the heart can cause coughing. Lumps in the breast with discharge from teats could be mammary carcinomas.

The good news is, not all of these signs point to cancer. Lots of other things can cause each and every one of these signs. The important thing to remember is to get it checked out by someone who knows what they are doing. If we are dealing with cancer, moving early is the way to go.

Best to all,

“The most common symptoms of bone cancer are lameness and pain. Symptoms can develop over a short period of time, or the lameness can be persistent, not responding to conservative treatment for a sprain or joint injury. In some cases, bony swelling can be seen or felt, sometimes by accident. The involved area can be tender to touch, but not always. In other cases, the first sign of bone cancer can be acute pain and lameness from a fracture through the cancerous bone.”