What causes it, and what is it?
Cats have tight maxillary lips held out by the maxillary canines. When a maxillary canine is extracted, the lip can suck in, causing the lower canine to painfully bite it.
This happens about 30% of the time in our experience.
Some patients suffer stoically, while others have violent reactions to biting their lips. Patients have been presented as having seizures! In addition, many cats will “lick” excessively as they are trying to use their tongue to move the lip out of the way. Extracting the lower canine can solve the problem, but this is challenging in cats, and thus we recommend coronal amputation and endodontic therapy (root canal or vital pulp therapy) as a less invasive alternative.
To avoid this complication, we recommend salvaging upper canines via root canal or other therapy whenever possible. When the extraction is vital, we generally recommend prophylactic reduction and endodontic therapy for the lower dog at the same time.