Feline Odontoclastic Resorptive Lesions (FORLs) - ‘Neck Lesions’

This is an inflammatory disease that develops at the base of the teeth, which is seen mainly in molars and premolars, but can also be found in canine teeth and incisors. This inflammatory disease is responsible for the internal erosion of the teeth. FORLs are progressive, can be singular or multiple and can be found on either side of the tooth. Between 25 and 75% of cats over 4 years of age suffer from FORLs at some time in their life.

There is no real understanding of what really causes this inflammatory disease. Some theories are that the inflammation caused by plaque may stimulate cells called ‘odontoclasts’ which eat away at the enamel of the tooth. Other possible causes include autoimmune disorders, viral diseases or a nutritional deficiency. These are not the same as cavities in humans which are caused by bacteria breaking down the enamel.

The initial signs are that the gum is inflamed. FORLs which have eroded through the enamel may be very painful. Cats with oral pain may appear irritable or aggressive, may have a change in appetite or food preference and may have difficulty chewing and eating (food falls from their mouth). You may also notice that they show pain when their jaw is touched and may have increased salivation or oral bleeding.

FORLs are difficult to see at the beginning of the process. Once lesions become established they may be easily visible but they are sometimes covered by areas of plaque or swollen gums. The most efficient way to diagnose them is by examination under general anaesthetic where the teeth can be examined using a dental explorer above and below the gum line. Any calculus on the teeth needs to be removed before a complete examination can be performed.

FORLs result in loss of tooth structure, starting with the outer enamel surface, usually at or below the gum line. The lesions begin as a loss of tooth enamel and can eventually spread to the dentine and then the pulp cavity, which contains the blood vessels and nerves to the tooth. In advanced stages the crown is lost and the affected root remains below the gum surface.

FORLs are classed in 5 stages based on the severity of the lesion;

	Loss of enamel only, extending less than 0.5mm into the tooth.
	Lesion extends into the dentine.
	Lesion extends into the pulp cavity, but good tooth structure remains.
	Lesion extends into the pulp cavity and there is extensive loss of tooth structure.
	Crown of tooth is missing but roots are present.

Although your cat has been diagnosed with FORLs and the affected teeth removed, it is possible the disease can occur in the remaining teeth at a later stage. Unfortunately, there is nothing you can do to prevent FORLs, however a good dental regime is still highly recommended.

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