Abscessed Pet Teeth

An abscessed tooth is an advanced form of an infected tooth and is most commonly seen on the upper jaw just below the dog or cat’s eye. This condition is usually caused by a fractured tooth that has been infected by the oral bacteria and the tooth eventually dies. The bacteria will travel through the infected root canal system and gain access to the jaw through the bottom of the roots. Once the infection reaches the jaw, it has access to the entire body, including vital organs, through the blood vessels.

These teeth have been dead and infected for a long time (sometimes years) and have just recently started to show outward clinical signs. The patient has been subclinically infected for a long time. The infected teeth harbour anaerobic bacteria which create a constant low-grade infection through the apex and into the surrounding bone.

Initially, the focus would be on relieving the pain and decreasing the amount of infection with pain medications and broad-spectrum antibiotics. This treatment should alleviate acute issues, but it will not solve the problem. We must definitively treat the tooth, and surgery should be performed before the antibiotics are finished to avoid developing resistance.

The bacterial infection causes bone destruction at the area of the root tip. If not treated the infection can travel through the bone of the upper jaw and break out as an abscess either on the gums over the tooth or on the skin under the eye. This is the only time that a root canal infection is usually noticed by the owner, as there is a visible wound on the pet’s face under the eye. With most dental infections, most dogs and cats do not show any outward signs of disease.

Treating the infected tooth will almost always resolve the condition. It is important to understand that treating this condition with antibiotics alone will not resolve this problem, but will only suppress the symptoms temporarily. The infection almost always returns and is still infecting the body between visible flare-ups. Once the tooth becomes infected, there is no way to effectively medicate the root canal. The reason the infection returns is that the tooth protects the bacteria within it. The pet’s immune system and the antibiotics cannot get into the tooth (it is like a fortress).

When the antibiotics are gone, the bacteria leave the tooth again, and the infection resumes. Further therapy is therefore required, regardless of the resolution of the acute problem. The infection will sit for a period of time and then recur, leaving your furbaby to suffer through that entire intervening period. This means your pet is still in pain, and their body is still suffering from an infection, even if no external signs are present. Furthermore, the bacteria may become resistant to the antibiotics if the infection is not completely resolved making it even more difficult to alleviate the acute symptoms of infection.

For these reasons, it is imperative to treat the inciting cause of the infection by dealing with the infected tooth. Ideally, we recommend doing this before the antibiotics run out. Do not assume that the infection is cleared because the swelling is gone. The problem will not be cured until the tooth is definitively treated.

Written by: College Manor Vetinerary Hospital



Cat opening its mouth to be examined

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Last updated: December 22, 2021

Dear Clients,

With recent changes to restrictions on businesses, we have made some important updates to our operating policies.


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Your dedicated team at College Manor Veterinary Hospital