Pulpitis by definition is inflammation of the tooth pulp. The pulp is the inner part of the tooth that consists of blood vessels, nerves, lymphatics, and connective tissues. In pets the most common reason for pulpitis is concussive force to a tooth, either from blunt trauma or chewing on items that are too hard. Typical cases seen in dogs result from accidental baseball bat swings, golf club swings, hit-by-car injuries, and rough play (or fights) with other dogs.

These teeth often appear discolored (pink, purple-to-gray). Similar to a skin bruise, the color change is a result of hemorrhage and the bursting of red blood cells within the tooth. When an intense light is applied to the tooth (transillumination), it appears dark or dull. Because the pulp is encased within a hard rigid chamber, any inflammation can rapidly increase inner pressure and lead to disruption of blood supply (ischemia). Eventually, pulpitis progresses to pulp necrosis and tooth death. In one study, 92% of discolored teeth displayed necrosis.
 
Why treat?
Why should these teeth be treated if our pets don't seem to mind? First, dogs and cats are unreliable about expressing pain. They have too many characteristics handed down to them from their wild ancestors, including a disinclination to display obvious signs of discomfort. People suffering from pulpitis report that the condition is painful! This is especially true in the early acute stages. But even in later chronic conditions, it is felt that a waxing and waning dull ache may be felt by our pets (again, this is based on what people report). Second, in addition to discomfort, dead or dying teeth are a potential source of infection. Through a process called anachoresis, bacteria naturally found in the bloodstream may be attracted to the area of non-vitalized pup and set up a thriving community. This active bacterial population leads to more inflammation, pain, and can possibly spread to other distant sites.

How to diagnose?
In addition to a complete oral examination and transillumination, dental x-rays may be obtained to help assess the tooth status. Unfortunately, in 42% of discolored, necrotic teeth, x-rays appear normal. Likewise, humans experiencing discomfort due to pulpitis do not always show changes on x-rays. X-ray evidence, when present, may include wider than normal pulp canals due to odontoblast death and delayed maturation; narrowed, strictured, or obliterated pulp canals due to accelerated calcification; periapical radiolucency; and/or internal or external root resorption.

What to do?
For very young dogs and cats less than a year of age, the prognosis for saving a tooth suffering from reversible pulpitis is better than in older pets; in these limited cases anti-inflammatory medications may be of benefit. These teeth need to be monitored long-term (e.g. x-rays every 6 months for two years). In most cases, however, diagnosed pulpitis is irreversible and treatment should be directed toward removing the source of inflammation (i.e. affected pulp). Definitive treatment for affected teeth includes endodontic therapy (root canal therapy) or extraction.