Any pet tooth that is not the normal color is almost certainly dead and infected. This means that teeth which are purple, yellow, grey, or brown are very likely to be a significant problem for your pet. In fact, it is estimated that 93% of discolored teeth are dead and infected, which means that can be painful and/or infected to your dog or cat. Unfortunately dogs and cats almost never show obvious signs of oral pain, therefore they often go untreated.
It is important to determine if the discoloration is coming from within the tooth or on the surface. Surface staining can be caused by metal or from enamel wear and is usually not a major problem. However, if the whole tooth is discolored, then it is typically not a surface problem but rather an internal tooth issue and is in all likelihood the tooth is dead.
The main cause of tooth death in an intact dog or cat tooth is the disruption of the tooth’s blood supply. The disruption usually occurs due to trauma, either to the jaw or to the tooth itself. The only symptom/sign you may see is a discoloration of the tooth. Once the tooth dies, it can become infected through what used to be the blood supply. Once the tooth becomes infected, it acts as a bacterial fortress allowing the infection to spread out to the rest or the body.
We previously thought that we could to rely on dental x-rays to determine if a discolored tooth is infected. However, a study in 2001 showed that almost all discolored teeth are dead and/or infected regardless of their appearance on x-ray. In addition, it has been our clinical experience that all discolored teeth are dead.
Therefore, we recommend treatment for all discolored pet teeth.