Good dental hygiene is very important for people and dogs as some oral tumours form when the mouth is not clean. Yearly dental check ups will be ideal. In February 2013, I encountered a case of a dog with bleeding in the mouth and face.
I was 50% correct. There was a large oral tumour shaped like an oval elongated tumour! Veterinary medicine throws surprising oral tumours to me even after 40 years of practice! The dog was eating food under this tumour which expanded to fit the length and width and height of the oral cavity. I doubt I will ever see another case similar to this.