FORLs (Feline Odontoclastic Resorptive Lesions)

FORLs are a common condition that affects up to 75% of ALL cats over 6 years of age. Often multiple teeth are involved and the lesions can be found anywhere on the tooth including below the gum line.

Odontoclasts are cells whose normal function is to remove the roots of the deciduous (baby) teeth as the permanent teeth erupt. Once the permanent teeth have erupted from the gumline, odontoclasts have no further normal function. For some reason, in some cats, the stem cells in the periodontal ligament differentiate into odontoclasts (no one has yet ascertained what the stimulus is) and these begin to attack the permanent dental structures.

This means that Odontoclasts are normal cells, which just happen to be in the wrong place at the wrong time! The odontoclasts basically eat their way into the tooth! Once the dentine is exposed the tooth becomes extremely painful and eventually the lesion will invade the pulp of the tooth where the nerve is (even more painful). The process continues until the root and crown become separated and finally there is loss of the crown.

Clinical signs

Cats may not show ANY clinical signs as they are experts at masking their pain.

  1. Pain, pain, pain – FORLS are one of the most painful conditions a cat can have. A cat in pain = A cranky cat!
  2. “Teeth Chattering” or repetitive jaw movement especially during or after eating or drinking = acute dental pain.
  3. Salivation or drooling
  4. Changes in preference for food (often avoiding hard foods)
  5. Foul smelling breath with inflamed gums
  6. Gingival hyperplasia (granulation tissue growing up over the lesions in an attempt to protect the sensitive tooth).
  7. In advanced cases a pinkish discolouration to the tooth
  8. Heavy calculus and tartar build up on the affected side of the mouth – as the cat is avoiding using this side of the mouth due to pain. Note this is usually only evident if only one side of the mouth is affected.


  • If FORLs occur above the gum line they can be easily seen, however if they occur below the gum line they can only be found using dental radiographs. Therefore we recommend dental radiographs of all cats.

Assessment and Treatment

  • The first step is to complete a thorough dental assessment of your cats teeth under general anaesthetic. This allows our veterinarians to complete dental probing and dental xrays (remember sometimes these lesions are below the gum line and the tooth can look normal above the gumline). This assessment will allow us to establish if FORLs are present and what teeth are affected.
  • If FORLs are found, then there is only one effective treatment – extraction (removal of the tooth). Extraction can be difficult due to the fact that teeth affected by FORLs tend to be very brittle and can fracture easily leaving part of the root behind.

Book your cat in for a dental scale and polish and we will do a comprehensive oral exam and then take full mouth dental radiographs at no additional charge. Hurry limited spaces available.

* Offer available until March 31st, 2020.

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