A tooth that turns grey, pink, purple or brown has almost always suffered bleeding inside the pulp chamber, and in most dogs that means the pulp has died. This is not a cosmetic change. A non vital tooth is a source of pain and infection, and the veterinary options are root canal treatment or extraction. It needs assessing promptly.
What the colour is actually made of
Inside every tooth sits the pulp, a chamber containing blood vessels, nerves and connective tissue. A blow to the face, a hard knock against a fence, a collision at speed, a bite from another dog or the strain of chewing something unyielding can rupture those vessels without cracking the crown at all. Blood then leaks into the dentine tubules, which are the microscopic channels running through the layer beneath the enamel.
The colour follows the chemistry of blood breakdown. Early on the tooth may look pink. Over weeks it darkens through purple and brown to a dull grey, and a tooth that has been discoloured for a long time is often uniformly grey and slightly translucent compared with its neighbours. Because the crown itself is intact, owners frequently notice the colour long after the injury and cannot connect it to any particular event.
The important part is what happened to the pulp during that bleed. Pressure inside a sealed chamber rises, blood supply is cut off, and the tissue dies. Studies of discoloured teeth in dogs have consistently found that the large majority are non vital, which is why veterinary dentists treat discolouration as evidence of pulp death rather than as a possibility to monitor.
Why a dead tooth is not a quiet tooth
The intuition that a dead nerve means no pain is the reason these teeth get ignored, and it is wrong. Dead pulp tissue becomes a reservoir for bacteria inside a chamber that the immune system and the bloodstream can no longer reach effectively. Infection then spreads out through the root canal system to the tip of the root, where it inflames the surrounding bone.
That is the painful part, and it is also the part that does not show on the outside until it is advanced. Over time the process can produce bone loss around the root apex, a swelling on the gum, or a draining tract. Facial swelling below the eye is a common presentation for an upper carnassial tooth, and it is sometimes mistaken for an insect sting or a skin infection.
The AVMA's guidance on pet dental care makes the general point that oral disease in companion animals advances well ahead of any outward sign, and discoloured teeth are one of the clearest examples of that principle.
Distinguishing the causes of a discoloured tooth
Tartar is the most common thing a discoloured tooth turns out not to be. Tartar is a deposit sitting on the surface, usually yellow to brown, usually heaviest at the gum line and on the outer surfaces of the back teeth, and usually present on several teeth at once. A single tooth that is a different colour all the way through, from tip to gum line, is a different finding entirely.
Colour intensity is not a reliable guide to severity either. A faintly pink tooth and a deeply grey one can both be non vital, and the shade mostly reflects how long ago the bleed happened rather than how much damage was done. Owners sometimes reason that a subtle colour means a minor problem, and that reasoning does not hold. The shade tells you about time; the radiograph tells you about the tooth.
What happens at the appointment
Your veterinarian will examine the tooth, compare it with the same tooth on the other side, and assess the surrounding gum. A definitive answer requires a dental radiograph taken under general anaesthesia, because the question is what the root and the bone around it look like, and that cannot be seen from outside.
Radiographic signs of a non vital tooth include a pulp chamber that is wider than its counterpart on the opposite side, because a dead tooth stops laying down dentine while the living one continues, and areas of bone loss at the root tip. Those findings determine which treatment is appropriate.
There are two legitimate treatments. Root canal therapy removes the dead pulp, disinfects the canal and seals it, keeping the tooth in place, which matters for the large working teeth. Extraction removes the tooth altogether. Both resolve the problem. Monitoring is not a third option once discolouration is established, and a veterinary dentist will explain why in terms of what the radiograph shows for your particular dog.
Keeping the rest of the mouth in good shape
Whatever happens to the affected tooth, the other forty one still need looking after, and a dog recovering from dental treatment is often more sensitive about having their mouth handled for a while. Ask your veterinarian when to restart home care and what texture is appropriate.
For dogs with sensitive mouths, softer options exist. Ark Naturals Soft Brushless Toothpaste is the softer format in Ark's brushless range, described by the brand as a gentler chew for sensitive chewers that helps reduce tartar build up, with the same functional approach as the original in a softer form. It comes in Small and Large.
Be clear about the boundary. A chew is a daily plaque control habit. It does not treat a discoloured tooth, it does not resolve infection around a root, it does not repair pulp, and periodontal disease remains a veterinary diagnosis that requires anaesthesia and radiographs to establish. No Veterinary Oral Health Council seal is claimed by Ark for this chew. Nothing in the home care aisle changes the plan for a tooth that has already died, and treating the grey tooth comes first.
It is worth knowing which teeth veterinary dentists treat as strategically important, because it shapes the conversation. The canines anchor the front of the mouth and support the lip, and the upper fourth premolar and lower first molar do most of the shearing work. Losing one of those is manageable, and thousands of dogs live well without them, but it is the reason root canal treatment is more often discussed for those teeth than for a small incisor.
What to do now
Book a veterinary appointment for any tooth that has changed colour, even if your dog seems entirely well, and even if the colour has been there for months. Go the same day if there is facial swelling, a lump or draining spot on the gum above the tooth, bleeding, obvious pain, or a dog who has stopped eating.
Ask directly whether a dental radiograph will be taken, since the assessment depends on it, and ask whether referral to a veterinary dentist is appropriate if root canal treatment is being considered for a strategically important tooth. Ask about pain relief in the interim, and never give human painkillers, several of which are dangerous to dogs. Mention any known trauma, including incidents from years earlier, because that history helps.
Frequently asked questions
Is a grey tooth in a dog an emergency?
It is not usually an emergency in the sense of needing care within the hour, but it is not something to postpone either. A discoloured tooth is strong evidence of pulp death, and the infection that follows progresses silently. Book an appointment within days rather than months, and go urgently if there is swelling, bleeding or evident pain.
My dog is not in pain, so does the tooth need treating?
Almost certainly yes. Dogs conceal oral pain extremely effectively, continuing to eat and behave normally with teeth that would have a person in a dentist's chair. Owners very often report that a dog became noticeably brighter after a dead tooth was treated, which is the clearest available evidence that the discomfort was there all along.
Can a discoloured tooth in a dog recover its colour?
Very occasionally a mildly affected tooth recovers vitality and lightens, but this is the exception rather than the expectation, and it cannot be assumed. The only way to know whether a tooth is alive is a radiographic assessment under anaesthesia, which is why waiting to see whether the colour improves is not a plan your veterinarian will recommend.
What causes a tooth to go grey in the first place?
Trauma is the usual answer: a knock to the face, a fall, a collision with furniture or another dog, a hard pull on a tug toy, or chewing something too hard. The impact ruptures blood vessels inside the pulp without necessarily breaking the crown, and blood products then stain the dentine from within.
Should the tooth be extracted or root canalled?
Both are valid and the choice depends on which tooth it is, what the radiograph shows, your dog's age and general health, and what is practical for your household. Root canal treatment preserves large functional teeth such as the canines and carnassials. Extraction is definitive and often the pragmatic option for smaller teeth. Discuss both with your veterinarian.
Related reading: Why Does My Dog Grind Their Teeth at Night?