There are some early signs that a canine might be affected with cancer or another illness that will need the treatment of a veterinarian. This can include increased drinking and urination without reason, such as a diet change. Increased itching even when the pet is flea free and has been treated with flea medication can also be another sign. 

Some of the other signs that can be a symptom of cancer as well as other illnesses in dogs is lethargy, or seizures, this can occur in dogs that have previously been very active and suddenly change behavior. This is not a sign or symptom of cancer in the puppy that calms down as they become an adult, which is natural behavior in canines.

Facial flinching or twitching can be a sign of nasal cancer and is often accompanied by loud breathing or panting. There can be nasal bleeding and when the dogs face is touch or almost touched they will often flinch in anticipation of the touch.