A hole in a tooth in a dog or cat
A “hole” in a tooth means the tooth has lost some of its hard tissue, and it will not fill in on its own. In cats, a pit at the gumline or red tissue that seems to grow into the tooth is most often tooth resorption (TR). In dogs the cause may be caries, an enamel defect or a fracture that has exposed the dentine or the pulp. How deep the damage goes can only be seen on dental X-rays.
- TR 1–2A defect at the gum lineA small pit where tooth meets gum, with red gum tissue growing into it. It may already hurt.
- TR 3The defect reaches the pulpThe tooth hurts, especially when touched or while eating, even if it looks almost intact.
- TR 4The crown breaks downThe crown weakens and may break off. What happens to the root depends on the resorption type, which only an X-ray shows.
- TR 5The crown is goneGum covers the root and the tooth seems to have “fallen out”. Root remnants show only on a radiograph.
Important note for owners
Tooth resorption (TR) is not caries: the tooth is broken down by the body's own cells, and the process continues even under a filling. It also occurs in dogs, so a “hole” at the gumline in a dog should be checked on X-rays too.
Most common possible causes
- —Tooth resorption (TR). The tooth's hard tissues are gradually destroyed by the body's own cells — odontoclasts, usually starting on the outside, at the root surface near the gumline. The defect fills with red gum tissue; once it opens into the mouth it is usually painful, and the process progresses.
- —Caries in dogs. True caries does occur in dogs: a dark, softened area, usually in the pits on the chewing surface of the upper first molars (109 and 209). It is caused by acids produced by plaque bacteria.
- —Enamel defect. If the animal was seriously ill or had a high fever while its teeth were forming, the enamel may be left thin or pitted, and the pits collect plaque easily.
- —Fractured tooth. A chipped-off piece exposes the dentine — the sensitive tissue under the enamel. The defect left by a fracture often looks like a “hole” or a step in the tooth.
- —Exposed or dead pulp. A pink or black dot in the centre of the defect may mean the pulp is exposed or already non-vital. A smooth, hard brown area in the centre of a worn surface is often protective (tertiary) dentine; it can only be told apart from an exposed pulp with an explorer and on X-rays.
When not to postpone an exam
- ✓Any “hole”, pit or step on a tooth
- ✓A brown or dark patch on the chewing surface of a tooth
- ✓Red gum tissue that seems to be growing onto the tooth
- ✓A pink or black dot in the centre of the defect
- ✓Your pet reacts with pain while eating, chatters its teeth or its jaw trembles
- ✓Your pet chews on one side only or drops hard treats
Urgent help needed
- ✓Rapidly increasing swelling of the face, cheek or under the eye
- ✓Active bleeding that will not stop
- ✓Complete refusal of food and water
- ✓A sudden deterioration in general condition
What you can do at home
- ✓Lift the lip and photograph the tooth in daylight. You can send the photos for an online consultation on Telegram, but they do not replace an examination.
- ✓If eating is painful, offer soft or soaked food for the time being.
- ✓Keep brushing the teeth with pet toothpaste, but leave the painful tooth alone.
- ✓Note whether your pet chews on one side only and whether it drops food — this helps at the consultation.
What not to do at home
- —Don't wait until the tooth “starts to hurt”: cats and dogs hide pain, and the defect keeps getting deeper
- —Don't use human toothpaste or gels — xylitol in some of them is toxic to dogs
- —Don't give human painkillers — many of them are toxic to cats and dogs
- —Don't give hard bones, antlers or tough chews — a weakened tooth can break
- —Don't try to clean or “seal” the defect with a toothpick, glue or any other material
What diagnostics may be needed
- ✓Consultation: the teeth, gums, bite and how your pet eats
- ✓Examination of every tooth with a fine dental explorer under anaesthesia as part of COHAT
- ✓Full-mouth dental radiography: depth of the lesion, state of the pulp and root, and for TR its type, which determines the treatment
- ✓If needed, transillumination: shining a bright light through the tooth to help assess the pulp
To the eye, a “hole” often looks smaller than it is: resorption may already have destroyed the root, and caries may have reached the pulp. X-rays also often reveal affected teeth that look healthy in the mouth. That is why I plan treatment only after probing and dental X-rays.
Unfamiliar term in the diagnosis?If the report mentions TR, FCGS, pulpitis or a periodontal stage, the glossary explains each term briefly.GlossaryHow treatment may proceed
- ✓Tooth resorption (TR) in cats and dogs: extraction or — only for a specific type on the X-rays (the root is being replaced by bone), with no inflammation around the tooth and no stomatitis — crown amputation; a filling does not help
- ✓Caries in a dog with a healthy pulp: removal of the affected tissue and restoration (a filling)
- ✓Root canal treatment if the pulp is involved and the tooth can be reliably restored
- ✓Extraction of a tooth that cannot be saved
- ✓Fissure sealing — prevention of caries in the deep pits of the chewing teeth, where they are suitable
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Enamel Defect in a Dog: Canine Tooth Restoration
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Frequently asked questions
If it is tooth resorption (TR), no. Resorption continues under and around the filling, so the filling eventually falls out and the pain returns. The affected tooth is extracted or — only for a specific type of resorption on the X-rays, where the root is being replaced by bone, and with no inflammation around the tooth or stomatitis — crown amputation is performed.
Yes. The typical site is the pits on the chewing surface of the upper first molars, where caries looks like a dark, softened area. If the pulp is healthy, the affected tissue is removed and the tooth is restored; if not, root canal treatment or extraction is needed.
A normal appetite does not mean the tooth doesn't hurt: animals adapt by chewing only on the other side or swallowing pieces whole. Resorption and caries do not stop on their own, and the deeper the lesion, the fewer treatment options remain.
A photo helps to judge urgency, and you can send it for an online consultation on Telegram. But the depth of the lesion and the state of the pulp and root can only be seen under anaesthesia — with an explorer and on dental X-rays.
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