There are many causes for tooth death in animals. The scary part is that these animals will almost never show outward signs of pain, therefore they often go The most common is when the root canal becomes exposed, as with a broken tooth, deep carious lesion, or a severely worn tooth. These conditions are apparent on oral exam, and are discussed on their own pages. There are, however, times when the tooth will be intact, but will be non-vital anyway. One cause is a periodontal lesion that progresses to the apex (or bottom of the tooth) and infects the tooth through the bottom. This is usually discovered during a prophylaxis (cleaning) when the veterinarian finds a very deep pocket. Dental radiographs are necessary to confirm the diagnosis.

The other cause of death in an intact tooth has to do with the blood supply to the tooth. The first is that a systemic infection can affect the tooth through the apex of the tooth. The other is by a disruption of the blood supply. The disruption usually occurs due to a significant trauma, either to the jaw or the tooth itself. The only outward sign you may see in this case is a discoloration of the tooth. Not all the teeth that are discolored are dead, however, so I recommend dental radiographs on all discolored teeth to determine the vitality of the tooth. Also, not all teeth that are dead will be discolored, for this reason, some veterinary dentists recommend full mouth radiographs during all dental procedures.