‘Neck lesions’, more properly feline odontoclastic resorptive lesions (FORL), are a common dental issue in cats. They are thought to affect more than 70% of cats over the age of 5.

In the early stages, these lesions may not cause signs or be easy to spot. They do have the potential to cause significant pain, eventually leading to loss of tooth structure and fractures of the affected teeth. Cats are known to be good at hiding pain, so it’s considered that many cases may be missed. Here we will go into more detail about what these lesions are, and how you might know if your cat is suffering from them.  

What exactly are FORLs?

A FORL is an erosion in the tooth, usually at the point where the gum meets the crown of the tooth. Because of this usual location they are also often nicknamed ‘neck’ lesions (because it’s the ‘neck’ of the tooth! – Ed.). They can also be found below the gum line. We still do not really know why cats get these lesions. What we do know is that odontoclasts, which break down the hard structure of the tooth, are found in these erosions.

It’s a progressive condition characterised into three stages: an acute phase, a chronic phase, and a remodelling phase. It starts with loss of the outer layer of the root (cementum) forming a cavity and progressing to the inner layer (dentin). These layers are replaced with a bone-like tissue in the remodelling stage. Finally, the central pulp of the tooth is breached along with the enamel surface of the crown. At this point the tooth structure is undermined and will fracture easily. 

Although they occur commonly in cats over the age of 5, the risk increases with age. Lesions are most common in the lower premolars and when they happen are often symmetrical (both sides of the mouth at the same time).

How do I know if my cat has them?

Early lesions seem to cause minimal pain to the cat, thus they will show minimal signs to you, the owner. Very often these cats will eat normally. Studies have actually found that 29% of seemingly healthy cats have these lesions, with this percentage increasing with age.

When the lesions progress to affect the pulp or expose the dentin they are likely to cause pain. Cats tend to hide pain well though, so even in these cases signs may be subtle. Some cats gobble their food, so they do not have to spend much time chewing as it causes pain. This may be mistaken as a good appetite.

Sometimes cats will preferentially chew on one side of the mouth, which may not be spotted at home. They may also prefer dry over wet food, as the wet food may ‘stick’ to the sore tooth. Cats may stop eating altogether, although this is rare. They may show obvious signs of pain in their mouths, such as dribbling or pawing at the face. 

How your vet can help

Annual vet checks at a minimum give your vet the chance to check your cat over generally which would include a physical dental check. This is how many later stage lesions are picked up. 

However, early change will not be visible, even by a vet, as often there may be no visible signs to the naked eye at this stage. Sometimes the gum around the affected tooth can become inflamed, reacting to the cavity within the tooth. During the end stage, there may be a cavity visible, or visible changes to the tooth. The gum may try to fill the cavity in the tooth, leaving an area of gum visible growing out of the hole. If your vet presses around this area, it may elicit some pain. With late stage lesions there may be obvious erosion of the crown of the tooth visible, or even fractures. 

If FORLs are suspected, then your vet will need to carry out a full anaesthetic so they can probe under the gum line to detect erosions and cavities. X-rays are essential for detecting early changes. Studies have also demonstrated that the resorption can occur anywhere on the root surface, not just at the visible gum margin.

The only way to detect these would be by taking dental x-rays. Just looking at the teeth, and even probing may miss many lesions. Full mouth x-rays are recommended for all cats presented for dental therapy. Not all veterinary practices have dental x-ray facilities. Referral to a specialist veterinary dentist or practice with these facilities may be needed. 

What are the treatment options?

Unfortunately, given there is no known treatment to prevent the development of these lesions, there is nothing we can do to prevent them. The aim therefore is to relieve pain. 

Cavities produced by FORLs are not due to decay like in humans. They also cannot be filled, so the treatment at this stage is removal of the tooth. When the root has been extensively resorbed it is often not possible to extract all the tooth substance so the crown alone can be removed, and the gum sutured. The remaining root can be left to resorb. X-rays would be needed to know which of these treatment routes would be best. Resorbed roots may be replaced by a bone-like substance making it difficult or even impossible to remove. 

It’s also important to understand that if your cat suffers with one FORL lesion, that more teeth could be affected at any time in the future. Regular vet checks are important to attempt to catch any problems early. 

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