Discolored Teeth in Dogs: From Purple Pulpitis to Brown Stains

You are playing tug with your dog, and you catch a glimpse of their teeth. Instead of the usual white, you see a tooth that looks bruised. Maybe it is pink, purple, or a dull, lifeless grey.

Your first instinct might be to grab a toothbrush. But if the stain is coming from the inside, no amount of scrubbing will fix it.

The color of a dog's tooth is a direct window into the health of the pulp — the living nerve center inside the root. When that color changes, it is almost always a sign of trauma, infection, or developmental damage.

Some stains are just surface dirt. Others are biological time bombs waiting to cause an abscess.

This guide breaks down the color spectrum of canine dental disease, helping you distinguish between a simple stain and a dying tooth that needs immediate surgery.

Intrinsic vs. extrinsic: Where is the stain?

Before you panic, you need to figure out where the color is coming from. Veterinarians classify dental stains into two types: extrinsic and intrinsic.

Extrinsic staining is surface level. It sits on top of the enamel. This is the accumulation of plaque, tartar, food pigments, or even blood from chewing on a raw bone. If your dog chews on metal cage bars, they might even rub a metallic grey residue onto the tooth surface. In these cases, the tooth underneath is usually healthy. You can often scrape these stains away with a fingernail or a professional scaling.

Intrinsic staining is different. The color is locked inside the tooth structure itself. It comes from the dentin or the pulp chamber. This happens when blood cells burst inside the tooth, or when medications bind to the enamel while the tooth is developing. Because the pigment is part of the tooth matrix, you cannot brush it off.

The rule of thumb is simple. If the surface feels rough and raised, it is likely external tartar. If the tooth surface is smooth and glossy but the color is "wrong," the problem is coming from the inside.

The "bruised tooth" progression (pink, purple, grey)

Teeth are alive. Just like your skin, they can bruise if they get hit hard enough. This usually happens from blunt trauma such as catching a heavy frisbee, banging into a coffee table, or chomping down on a rock.

When a tooth takes a hard impact, the impact doesn't always break the enamel. Instead, it shocks the pulp inside. The tiny blood vessels explode, flooding the dentin tubules with blood. This kicks off a predictable timeline of death.

• Pink or Red (Acute Pulpitis): This is a fresh bruise. The injury just happened. The pulp is inflamed and actively bleeding internally. Because the pressure has nowhere to go inside the rigid tooth, this stage is incredibly painful.
• Purple or Blue: As time passes, the blood trapped inside the tooth begins to lose oxygen. Just like a bruise on your arm turns purple after a day or two, the hemoglobin in the tooth changes color. This signals that the tooth is dying.
• Grey or Dark Grey: This is the final stage. The blood supply has been severed completely. The pulp tissue has rotted (necrosis).

There is a dangerous myth that if a grey tooth isn't bothering the dog, you should leave it alone. This is false.

Studies show that 92% of discolored teeth are dead. A dead tooth is no longer part of the body's immune system. It becomes a hollow bunker for bacteria to hide in. Over time, this bacteria leaks out of the root tip, causing a silent abscess that destroys the jawbone without you ever seeing a swollen face.

Yellow and brown: Tartar, tetracycline, or hypoplasia?

Yellow is the most common color you will see in a dog's mouth, but the cause isn't always simple dirt.

Calculus (Tartar): This is the most likely culprit. Plaque is soft and sticky, but within 48 hours, it calcifies into hard, yellow-brown rock called tartar. It starts at the gumline and creeps downward. The good news is that this is purely external. A professional scaling can pop this crust off, revealing healthy white enamel underneath.

However, some yellow stains are permanent. Untreated plaque buildup is the main cause of gingivitis and periodontitis in dogs.

Tetracycline Staining: If a pregnant dog or a young puppy is treated with tetracycline antibiotics, the drug binds to the calcium in the developing teeth. When the adult teeth erupt, they have distinct yellow or golden-brown bands wrapped around them. This color is locked into the mineral structure of the tooth and will darken with exposure to sunlight over time.

Enamel Hypoplasia ("Distemper Teeth"): If a puppy suffers a high fever or a virus like Distemper while their adult teeth are forming, the enamel stops developing. When the teeth finally come through, they look patchy, pitted, and stained brown. Unlike the smooth discoloration of antibiotics, these teeth feel rough to the touch. The protective shell is missing, leaving the softer dentin exposed and prone to rapid wear.

Rare colors and cavities (black spots)

In humans, a black spot usually means a cavity. In dogs, true cavities (known as caries) are surprisingly rare.

Because dogs don't drink soda or eat sugary snacks, the bacteria that cause tooth decay starve. Less than 5% of dogs develop cavities. When they do appear, they usually show up as soft, dark brown or black pits on the flat top surface of the back molars.

If you see a black spot on a canine tooth or the side of a premolar, it is almost certainly not a cavity.

It is likely metal staining.

This is frequent in dogs with separation anxiety who chew on wire crates or chain-link fences. The constant friction grinds metal micro-particles into the enamel. Over time, this creates a distinct grey or black discoloration on the back of the canine teeth. It looks like the tooth is rotting, but the stain is actually superficial.

The "flashlight test" and diagnosis

If you aren't sure if a tooth is bruised or just dirty, you can try a simple trick at home. Veterinarians call it transillumination.

Take a bright, focused flashlight (like the LED light on your phone) into a dark room with your dog. Shine the light directly through the back of the discolored tooth.

A healthy, living tooth is translucent. The light will pass through it, making the tooth glow a warm pink or orange color. A dead tooth is opaque. The coagulated blood inside blocks the light, making the tooth look dark or shadowed compared to its neighbors.

However, this test isn't perfect. To know for sure, your vet needs to look below the surface.

Dental X-rays are non-negotiable for discolored teeth. The vet is looking for a specific warning sign called a periapical lucency—a dark halo around the tip of the tooth root. This halo means the infection inside the dead tooth has leaked out and dissolved the jawbone. If that halo exists, the tooth has to go.

Treatment: Bleaching vs. surgery

So, what can you do about a discolored tooth? In veterinary medicine, the goal is almost never cosmetic. We don't fix teeth to make them pretty; we fix them to stop the pain.

Whitening: While bleaching products exist for dogs, they are rarely used outside of the show ring. The discoloration is usually internal, so applying a surface bleach does nothing to fix the dead pulp inside.

Vital Pulp Therapy: If you catch a "pink" tooth within 48 hours of the injury, a specialist can sometimes save it. They drill into the tooth, remove the inflamed top layer of the pulp, and place a medicinal dressing over the nerve. This keeps the tooth alive. But the window of opportunity is tiny.

Root Canal or Extraction: For the vast majority of grey, dead teeth, these are the only two options. You must remove the source of the infection. A root canal cleans out the dead space and seals it, allowing the dog to keep the tooth. Extraction removes the tooth entirely. Both eliminate the risk of an abscess.

Sealants: For dogs with enamel hypoplasia (brown, pitted teeth), the tooth is alive but painful because the nerves are exposed. Vets can apply a bonded sealant—similar to a cavity filling—to smooth over the pits and block the sensitivity.

Prevention for Surface Stains: If the diagnosis is simply brown tartar, you can breathe a sigh of relief. You don't need surgery; you need a cleaning and a better home care routine.

Once the vet scales the tartar off, your job is to keep it off. While brushing is ideal, many owners find success using seaweed supplements for dogs. The bioactive compounds in the seaweed work systemically to prevent plaque from calcifying into that hard brown crust again, keeping the pearly whites actually white.