8. Lethargic behavior
Both humans and dogs suffer this symptom, the cancer drains the victim of all their energy. Although this symptom is almost always present when cancer shows up, the timing is often unexpected and different for victims of cancer. Knowing your dog’s behavior is imperative to being able to differentiate whether or not the dog is just being lazy, or if it is truly feeling drained. If you have decided that the behavior is irregular, you should take your dog to the veterinarian for a check up.