Feline resorptive lesions (otherwise known as feline odontoclastic resorptive lesions or neck lesions) are a very common cause of dental pain in our feline friends. In fact, studies have shown that once cats reach middle age, at least half of them will have one or more resorptive lesions near or under the gumline, with the number of lesions increasing with age. Similar lesions also occur in other species, including man and dogs, but are relatively rare.

Resorptive lesions start as small holes in the structure of the tooth, which progress in size until they cause large defects. They are not the same as caries (or cavities) in humans, which result from bacterial acids eroding the enamel (usually due to a sugary diet). Feline resorptive lesions are caused by the cat’s own cells (called odontoclasts) destroying the tooth from underneath the enamel. Affected teeth are very sensitive, and if the nerve is exposed they can be intensely painful. Often the crown of the tooth snaps off, leaving a painful retained root in the jaw. If your cat has unexplained “missing teeth”, they may well have been lost through this process.

Signs that your cat may be suffering from resorptive lesions include reluctance to chew, chewing on one side, drooling, pawing at the mouth, lethargy or bad breath. However, many cats will not show their discomfort until the pain becomes unbearable. Visible defects in the tooth, localised inflammation, swelling of the gum to cover the lesion, or an area with increased buildup of tartar may be seen. Small lesions are often only detected under anaesthesia.

Treatment usually involves extraction, as fillings are ineffective (the resorptive process simply continues inside the tooth structure underneath the filling). Dental radiographs are very useful in determining the extent of the lesions and the best course of action. Despite years of research, veterinary dentists still do not understand what exactly triggers the cat’s odontoclasts to attack its own teeth – this makes it hard to recommend any effective preventative measures.