When the hard dental tissues begins to decay due to oral bacteria, it is referred to as Dental cavities or Caries. This condition is not very common in dogs. When it does occur, it can affect the crown or the roots of the teeth and is classified as pit-and-fissure caries, smooth-surface caries, or root caries.
Incipient smooth-surface caries appears as an area of dull, frosty-white enamel. A structural defect on the surface of the crown or root will be apparent, and will show dark, soft, decayed dentin which is the layer just under the enamel. Early stages may be reversible through re-mineralization but once the protein matrix collapses it becomes irreversible. Even if only one tooth has become irreversibly damaged, care must be taken to protect the remaining teeth, since dental surfaces in close contact with an established caries are at risk of developing a lesion as well.