Warts on old dogs are usually hard, round, and smooth.
They are rather common and are caused by a virus. If they become irritated or bleed, have them removed. Warts are often found in the mouth. They often disappear spontaneously without treatment. In any case, they do little harm unless there are so many in the mouth that they interfere with eating. In such cases, they can be removed surgically.
Whatever the age of the dog, no growth should be disregarded. Handled by the competent veterinarian in its earliest stages, the average growth can be permanently removed. If neglected for any length of time, it may become deeply embedded or malignant. Tumors of the breasts or testicles often develop in old age when dogs have not been spayed or castrated. These, unfortunately, have a high malignancy rate.