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The dental disease “FORL” (feline odontoclastic-resorptive lesion) has other names: neck lesions, tooth resorption, resorptive lesions, etc.

You can find out what is behind it and how it is treated in this article.

FORL – what is it?

FORL in the Cat 9

FORL stands for Feline Odontoclastic-Resorptive Lesions and is a degenerative disease of the teeth in cats. In the meantime, this disease is often just referred to as RL (resorptive lesions).

FORL is a dental disease in which the tooth and its roots dissolve. It is one of the most common and most painful diseases in cats: almost every third cat suffers from FORL, from the age of 5 years it is even every second – and this across all cat breeds. However, Persian cats and Siamese cats are apparently particularly frequently affected.

What are the triggers of FORL in cats?

Unfortunately, the exact cause is still unknown. However, there seems to be a disturbance in the calcium balance. As a result, cells (so-called odontoclasts) are activated, which begin to dissolve the tooth and root. The odontoclasts break down the dentin (tooth bone) by releasing calcium stored there. Dentin is the bone-like main component of the tooth. The decomposition of the dentin means the destruction of the entire periodontium and thus the end of the affected tooth.

The odontoclasts that decompose dentin are originally endogenous cells, which is why FORL can be classified as an autoimmune disease. Since the dentin is dissolved but the nerves of the tooth remain intact, the affected cats experience great pain.

There is evidence that reduced calcium intake in the feed could also be involved in the disease. You can ask your vet for a food recommendation that will provide your cat with adequate calcium.

How does the disease progress?

FORL in the Cat 10

As a rule, the roots of the teeth are affected first, before the visible part of the tooth is destroyed. Therefore, this disease is often overlooked for a long time.

There are three forms of FORL in cats:

Type 1 usually occurs together with plaque, tartar and inflammation of the periodontium (periodontitis) and gums (stomatitis). There is no healing process in the area of ​​the tooth roots.
Type 2 initially develops without the involvement of inflammation. The space of the dissolved root is filled with a bone-like substitute tissue, the teeth firmly grow together with the bone (usually they are “suspended” with connective tissue).
Type 3 is a combination of types 1 and 2. Both inflammatory and non-inflammatory processes occur on the same tooth.
As a rule, such changes, known as “resorptive lesions”, do not occur individually, but affect several teeth. If they are only visible in one place, it can be assumed that the process is just beginning on other teeth.

What are the symptoms of FORL in my cat?

In the early stages, FORL cannot be seen with the naked eye and the owners usually do not notice it either. Subtle signs such as B. a greater need for rest of the cat, stress behavior such as urine marking or similar. are often not associated with pain.

The cat only shows symptoms with advanced decay of the teeth. Because when the dentin in the root area is dissolved, the nerve in the tooth comes into contact with the bacteria in the oral cavity. Severe pain, inflammation, etc. are the result.

So, to recognize the symptoms of FORL in your cat, look for signs of toothache:

Changed behavior when eating, such as refusing dry food or crying out in pain when eating
increased salivation
Teeth grinding or chattering
Shaking or tilting the head

In the oral cavity, as the disease progresses, one can observe that teeth are apparently missing, but some of them are only broken off at the tooth neck. In addition (especially with FORL type 1) gingivitis and redness, as well as growths of the gums, occur.


FORL in the Cat 11

If you suspect your cat may be suffering from FORL, you should see a vet as soon as possible. You can find out in advance which veterinarian or veterinary clinic in your area has a veterinarian trained as a cat dentist and has the appropriate equipment.

The vet will examine the cats and probe the oral cavity. This means that he will feel the teeth and gums with a probe to find loose teeth, painful areas or areas with dissolved roots.

The preparation of X-rays is absolutely essential for the diagnosis of FORL, as this is the only way to see whether dentin has already dissolved under the gums. A complete “dental status” includes about six X-rays, which are made under a short anaesthetic. This is necessary, otherwise the quality of the images will not be sufficient.

Ask your veterinarian to take x-rays of your cat’s jaws when they regularly clean your cat’s teeth so that they can detect any decay in the roots of the teeth as early as possible. Since the teeth can only be cleaned professionally and under anesthesia in accordance with animal welfare, it is quite possible to take the X-rays at the same time.


The decay of the tooth substance can neither be prevented nor repaired. Therefore, all teeth attacked by FORL must be completely removed. The vet has to do this under general anesthetic and X-rays to ensure that all affected teeth have been completely extracted. Remnants of the tooth root remaining in the jaw can lead to a new focus of inflammation. The tooth gaps resulting from the extraction are then covered with gums and sewn up to prevent food residues from getting stuck in them. While the wound is healing, your darling will be given painkillers and antibiotics to prevent the fresh wound from becoming inflamed. Threads usually do not have to be removed as a self-dissolving thread is used. Your vet will call you in for follow-up visits to check the wound is healing.

The day after the operation, the cat can already eat again, even if it only eats wet food for a few weeks.

Living with FORL

For many cat owners, the operation of a cat suffering from FORL can be quite depressing, sometimes the cat no longer has any teeth or only a few.

Therefore, the first thing to say at this point is: Don’t worry! Your cat can get along just fine without teeth. Once all the wounds have healed, she will eat normally again, maybe better than before because the pain is finally gone. Some cats will need to make a permanent switch to wet food, but many will crack their jawbones again after a few weeks.

The amazing thing is that immediately after the operation, many cats are suddenly more approachable, happier and seek company. Despite the pain of the wound, they seem to be doing much better than before, showing how painful FORL can be.

How much should I expect to pay for my cat’s FORL treatment?

In principle, the treatment costs of veterinary practice are based on the fee schedule for veterinarians (GOT). Depending on the effort, different rates can be used as the settlement amount. It is therefore not possible to make a general statement about the costs.

Talk to your vet about the possible cost of treating your cat with FORL, they can explain everything you need to know.

FORL in the cat: conclusion

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FORL in cats is a common autoimmune disease in which the cat’s teeth dissolve from within, causing great pain. A cat with FORL cannot be predicted or prevented. In the course of a cat’s life, however, it will affect every second cat on average.

If you want to minimize the risk for your cat, then you should take her to your veterinarian regularly for a health check with control X-rays of her teeth. In this way, the disease can be detected as early as possible and the animal can be helped quickly.