What Is the Dark Spot on My Dog's Tooth?

He's half asleep on your lap, so you lift his lip to check one thing, and there's a dark spot on a back tooth. You tilt the phone torch for a better look. It doesn't rub off with your thumb.

An owner on r/DogAdvice posted the same moment this week, under the title "Just saw this dark spot on my dogs teeth. Should I be concerned?" Where the spot sits and what color it is tell you most of what you need, and you can check both right now. Here's how to read it, and which version needs the vet this week.

The quick answer

It depends on where the spot sits and what color it is. A yellow or brown crust along the gumline is likely tartar. A dark spot on the flat chewing surface can be a cavity. A whole tooth that has turned pink, purple or gray usually means damage inside the tooth, and that needs a vet.

Yellow or brown, right at the gumline

A reply in that Reddit thread guessed this one. The American Kennel Club describes tartar as "the yellow or brown build-up on the surface of the teeth." It hugs the edge of the gum and feels rough under a fingernail rather than smooth.

Tartar is plaque that has hardened. VCA Animal Hospitals says that "within 24 hours, plaque begins to harden by combining with salts that are present in the saliva," and that tartar can develop above and below the gum line. The part below the gum is the part you can't see. VCA adds that as tartar builds up along the gum line, it pushes the gums away from the roots of the teeth.

Don't try to scrape it off. VCA's guide to dental disease says tartar taken off an awake dog's teeth "is cosmetic only and does not diagnose or treat any dental disease present," and that a full general anesthetic is required for dentistry. If you're bracing for the bill, we broke it down in What a Dog Dental Cleaning Actually Costs.

A dark pit on the chewing surface

A spot on the flat top of a back tooth, away from the gum, is a different thing. Dogs can get cavities too. In the same AKC article, board-certified veterinary dentist Dr. Maria Soltero-Rivera says cavities "are incidentally found and noticed as dark spots on the flat surfaces of teeth." When probed, she says, they're sticky like fudge.

She also notes that a cavity can lead to infection inside the tooth. So a dark pit on a chewing surface is worth its own appointment, not a note for the annual checkup. Leave the probing to the vet.

One whole tooth gone pink, purple or gray

This is the one not to wait on. If the color is in the tooth itself, so the whole tooth looks darker than the ones beside it, the problem is on the inside. The Merck Veterinary Manual, in its section written for vets, says "a discolored tooth signifies endodontic disease and is evidence of previous trauma." The colors it names most often are pink, purple, gray or green, or simply a dull look.

The same section reports that 87% to 92% of teeth stained from the inside are thought to be dead inside, meaning the living pulp in the middle of the tooth has died, "and therefore warrant treatment." Merck's guide for dog owners puts the options plainly: "Treatment is either tooth extraction or a root canal procedure."

Your dog may seem completely fine, which makes this one easy to put off. Merck notes that once the nerve dies, the tooth "is thought to enter a quiescent phase in which it is no longer painful," and the owner guide adds that "most dogs mask their pain." He's still eating, so it doesn't feel urgent. That's why the vet will usually want X-rays, which Merck says are used to identify affected teeth and help decide the treatment.

How to get a proper look

• Pick a calm moment. After a walk, when he's drowsy, not in the middle of play.
• Use a side light. A phone torch held at an angle shows color better than the ceiling light.
• Lift the lip, don't open the jaw. Slide a thumb under the upper lip at the side and you'll see the back teeth and the gumline without a struggle.
• Compare it with its twin. Check the same tooth on the other side of his mouth. One that is darker than its match is the one to mention.
• Take a photo. It shows your vet what you saw, and next month it tells you whether the spot has changed.

If he won't let you near his mouth at all, My Dog Won't Let Me Brush His Teeth has a slower way in.

When to call the vet

Book an appointment this week for a whole tooth that has changed color, a dark pit on a chewing surface, or a tooth that looks chipped or cracked. Merck's owner guide says fractured teeth "should be inspected by a veterinarian to determine whether there has been damage to the tooth pulp."

Call sooner if you see swelling on his face, a red or black hole in a tooth, a tooth he won't let you touch, or he's eating less. Merck lists each of those among the signs of a damaged tooth.

Yellow or brown buildup at the gumline is the least urgent of the three. Put it on the list for his next checkup, and move it up if the gums look red or bleed.

Where a daily spray fits

Only the tartar has anything to do with daily care, and even there the job is the next layer. Home care won't replace the cleaning a mouth with built-up tartar needs, and it does nothing for a tooth that has changed color from the inside.

Because plaque starts to harden within a day, the habit has to be daily. Calmi DentaClean is a xylitol-free dental spray. Spray it on his teeth once a day, or add it to his food bowl if he won't sit still for it. It's there to slow new plaque and tartar between cleanings, and it won't lift a spot that's already there. It comes with our 90-day money-back guarantee.

FAQ

Is a black spot on my dog's tooth always a cavity?

No. A dark crust at the gumline is more likely tartar. AKC's veterinary dentist describes cavities as dark spots on the flat surfaces of teeth, and only an exam can confirm one.

Does a gray tooth hurt?

It may not seem to. Merck says a tooth whose nerve has died is thought to stop being painful, but the same section says most teeth stained from the inside warrant treatment. Have your vet look at it.

Can I scrape the tartar off at home?

No. AKC says that scaling at home is simply not sufficient, and VCA says tartar removed from an awake dog is cosmetic only. A vet cleaning under anesthesia also reaches below the gum line, where you can't see.