Pulpitis in a dog or cat:why the tooth hurts in silence and what to do about it

What the pulp is and why it becomes inflamed

On the outside the crown of a tooth is covered with enamel and the root with cementum; beneath them lies dentine, and in the centre there is a cavity containing the pulp: nerves, blood vessels and cells that lay down new dentine throughout the tooth’s life. The pulp runs from the crown to the root tip, and it is through the root tip that it connects to the bone and the bloodstream.

In young animals the walls of the tooth are still thin and the pulp cavity is wide, so even a small chip can reach the pulp. With age there is more dentine, and the cavity narrows.

The pulp is enclosed within the hard walls of the tooth. When it becomes inflamed and swells, it has no room to expand: the pressure inside rises and the blood supply is disrupted. This is painful, and the pulp may die.

Causes of pulpitis in dogs and cats

The pulp becomes inflamed when bacteria reach it or when it is injured. The most common scenarios:

• A tooth fracture that exposes the pulp. The teeth that break most often are the canines and the large upper fourth premolars — on bones, antlers, stones or cage bars, or from a knock. Bacteria from the mouth get straight into the pulp.
• A deep fracture without pulp exposure. Bacteria can reach the pulp through the tiny tubules in the dentine.
• A knock without a fracture — a fall, a blow against an object or a collision. Bleeding occurs in the pulp: the tooth turns pink and may later go grey or purple.
• Severe wear — from tennis balls, hard toys or chewing cage bars. If a tooth wears down faster than the pulp can protect itself with new dentine, the pulp becomes exposed.
• Tooth resorption (TR), when the defect reaches the pulp. Resorption is very common in cats and also occurs in dogs.
• Periodontal disease. A deep periodontal pocket can reach the root tip, and infection enters the pulp “from below”.
• Filing teeth down without anaesthesia and X-rays. That is why crown reduction is done only under anaesthesia, with X-rays, and — if the pulp is exposed — with vital pulp therapy and a filling.

In cats the canines are slender and the pulp extends almost to the very tip, so even a small chip off the tip of a canine often exposes the pulp.

Signs of pulpitis: what an owner may notice

The main difficulty is that dogs and cats usually do not show dental pain: they keep eating, playing and chewing toys. So pulpitis is most often noticed not from behaviour but from the tooth itself.

• A broken tooth with a pink, red or dark dot in the centre of the fracture
• One tooth is pink, grey, purple or brown — different from its neighbours
• A worn tooth tip with a pink or black dot (a smooth brown dot is usually protective dentine, but only a vet can tell them apart)
• Chewing on one side, food falling out of the mouth, taking hard treats gingerly
• Pulling the head away when the muzzle is touched, or pawing at the face
• Increased drooling, bad breath
• Swelling on the face, under an eye or on the lower jaw; a wound or a draining tract discharging pus

Swelling, a wound or a draining tract often mean that the pulp has already died and the infection has spread into the bone around the root. Swelling on the face is a reason for a prompt examination, and if it is growing quickly, or your pet is lethargic or not eating — the same day.

More on the symptom pages Broken tooth, Darkened tooth and Worn teeth. You can practise spotting changes like these in the “Spot the problem” challenge.

A darkened tooth: why colour matters

A pink tooth means bleeding into the pulp — most often after a knock. If the tooth turned pink recently, the pulp can sometimes still recover — in that case the vet may suggest monitoring. But often the inflammation continues, and the tooth gradually turns grey, purple or brownish.

So “it has darkened but doesn’t hurt” is mostly a misleading impression: a dead pulp is a source of infection inside the tooth, and the pain simply goes unnoticed. The colour of the crown does not show the state of the root, and even an X-ray with no changes does not prove that the pulp is alive: in the same study, 42% of darkened teeth showed no changes on X-rays. More about colour changes in the article Why has a tooth changed colour?

Why untreated pulpitis is dangerous

If the pulp is exposed or the inflammation is already irreversible, without treatment the pulp dies. Mild inflammation after a knock sometimes settles, but only a vet can determine that. When the pulp dies, the pain may even ease, and the owner feels that it has all passed. But the tooth cavity is now filled with dead tissue and bacteria, and the infection escapes mainly through the root tip into the bone.

There, inflammation develops around the root tip: the bone is destroyed, and an abscess may form. From the large upper fourth premolar, the first molar or a canine, the infection sometimes “breaks through” as swelling or a draining tract under the eye; from the lower teeth, on the lower jaw.

This inflammation can go on for months without noticeable signs, and all that time the tooth remains a source of chronic pain and infection.

How pulpitis is diagnosed

At the examination and consultation I look at the tooth, the gums and the bite, assess whether the pulp appears to be exposed and explain what is needed next. But the key is dental X-rays: only they show the root, the width of the pulp cavity and the bone around the root tip.

Sensitivity tests used in people (with cold or electricity) are of limited use in veterinary practice: they are done before anaesthesia, and the result depends on whether the animal tolerates them calmly and reacts visibly. So the decision is still based mainly on the examination under anaesthesia and dental X-rays, with monitoring over time if needed.

1. 01

   Examination and consultation

   I assess the tooth, its colour, the fracture, the gums and your pet’s general health, and plan the tests needed before anaesthesia.

2. 02

   Examination under anaesthesia

   I check the fracture with a dental explorer: whether the pulp is exposed and whether there is a crack running down to the root.

3. 03

   Dental X-rays

   I compare the tooth with the matching tooth on the other side. If the pulp died a long time ago, it has stopped laying down dentine, and the cavity is wider than in the matching tooth. There may be a dark area at the root tip — a sign of inflammation in the bone — but in the early stages the X-ray may still show no changes.

4. 04

   Treatment plan

   We decide together whether to save or extract the tooth, taking into account the X-rays, the age of the tooth and the time that has passed since the injury.

Treating pulpitis: save the tooth or extract it

The aim of treatment is to remove the pain and the source of infection. Depending on the situation, there are three options:

• Vital pulpotomy. If the fracture is fresh, only the top, contaminated part of the pulp is removed, then a medicated material and a filling are placed. If treatment is successful, the tooth stays alive and keeps strengthening from the inside — this is especially important for young animals. The pulp can still die later, so the tooth is checked periodically with X-rays.
• Root canal treatment (endodontics). If the pulp has already died or a lot of time has passed, it is removed completely, and the canal is cleaned and tightly sealed. The aim is for the tooth to stop being a source of pain and infection and to keep doing its job; the result is checked on follow-up X-rays.
• Extraction. If the tooth cannot be saved — there is a root crack, deep resorption or severe periodontal disease — or if you choose this route, the tooth is extracted surgically, with a follow-up X-ray. Dogs and cats live well without individual teeth.

Canines and the large chewing teeth are worth saving where possible: they are needed for grasping food and biting it into pieces. Examples from my practice: a tooth kept alive in a Jack Russell after vital pulpotomy, three broken canines in a young cat, two of which were saved with root canal treatment, and a zirconia crown in a Basenji that protects an endodontically treated tooth.

Why a broken tooth should not wait

An exposed pulp is in contact with bacteria from the mouth straight away, and with every day the chance of keeping it alive gets smaller.

If the window for vital pulpotomy has passed, root canal treatment may help save a mature tooth — this is decided based on the X-rays. But it is not worth waiting “until it starts to hurt”: the animal will not show the pain, and in the meantime the infection is spreading into the bone.

I have described what to do straight after a fracture in the article What to do if your dog breaks a canine tooth.

How to reduce the risk of pulpitis

In dogs, pulpitis most often starts with a fracture, so the main thing is to protect the teeth from injury.

• Do not give bones, antlers, hooves, hard nylon “bones” or ice. The thumbnail test: your nail should leave a dent in the item — otherwise it is too hard for teeth
• Do not leave tennis balls with dogs that chew them for hours: they gradually wear the teeth down
• Do not file or grind down teeth yourself
• After any injury to the muzzle, have your pet seen by a vet, even if the teeth look intact
• For cats, put nets on the windows: falls from a height often end in broken canines
• Regularly — for example, while brushing the teeth — lift the lip and look at the canines and the large back teeth: check for chips and for any change in colour

I go through safe and dangerous chews in the article Which bones can dogs have — and which break teeth.

How much does diagnosing and treating pulpitis cost

The first step is an examination and consultation: I assess the tooth and explain which X-rays and treatment may be needed. Diagnostics and treatment are carried out under inhalational anaesthesia with dental X-rays.

The cost of vital pulpotomy, root canal treatment or extraction depends on the tooth, the number of roots and the chosen method, so I give it after the X-rays.

Frequently asked questions