What Does Dog Tooth Decay Look Like? (Stages Explained)

Dog tooth decay usually looks like a band of yellow-brown or grey-brown crust packed along the gumline, gums that are red and slightly swollen where they meet the tooth, and — further along — teeth that look oddly long because the gum has pulled back off the root. In advanced cases you may see a tooth that is grey, pink or dark brown, a visible gap between tooth and gum, pus at the gum margin, or a tooth that wobbles when the dog chews.

True cavities — the dark pit in the chewing surface that people get — are uncommon in dogs. What almost every owner is actually looking at is periodontal disease: plaque mineralising into tartar, inflammation spreading beneath the gum, and the slow loss of the bone and ligament that anchor the tooth. It progresses in recognised stages, and it is largely invisible in its earliest and most treatable form.

Do dogs get cavities, or is this something else?

Dogs' teeth do decay, but not in the way human teeth do. Dog saliva is less acidic, the tooth shape is conical rather than flat-topped with deep fissures, and the canine diet is low in fermentable sugars. Carious lesions — classic cavities — do occur in dogs, most often on the flat chewing surfaces of the upper molars, but they are a minority finding. The overwhelming cause of tooth loss in adult dogs is periodontal disease.

Other animals vary the same way. Herbivores with continuously erupting teeth rarely develop cavities but get other dental pathology; cats get resorptive lesions that eat the tooth from the outside in. So yes, animals' teeth decay — the mechanism is just species-specific.

This also answers the comparison owners search for most: plaque is the soft, colourless bacterial film you can wipe off with a cloth, tartar is that film mineralised into hard yellow-brown calculus you cannot, and decay is the tissue damage happening underneath both. Plaque is the cause. Tartar is the visible evidence. Decay is the consequence.

Stage by stage: how canine dental disease progresses

Veterinary dentists stage periodontal disease by how much attachment — bone and ligament around the root — has been lost. That measurement is taken under anaesthesia with a periodontal probe and dental X-rays, which is why a photograph can suggest a stage but never confirm one. Use the chart below to orient yourself, not to diagnose.

Stage	What you can see	What is happening below the gumline
Stage 0 — healthy	Pale pink gums, tight gum margin, clean white or ivory enamel, no odour	Normal attachment; plaque present but controlled
Stage 1 — gingivitis	A thin yellow film near the gumline, a red line along the gum margin, slight bleeding after chewing	Inflammation only; no attachment loss yet, and this is the stage that can still resolve
Stage 2 — early periodontitis	Visible hard tartar, puffy red gums, breath that has turned sour	Up to about a quarter of the attachment lost; small pockets forming
Stage 3 — established periodontitis	Thick brown calculus, receding gums, roots starting to show, teeth looking longer	Roughly a quarter to half of attachment lost; deep pockets, bone loss on X-ray
Stage 4 — advanced periodontitis	Loose or missing teeth, pus, exposed root surfaces, heavy dark calculus, strong rotten odour, sometimes facial swelling under the eye	More than half the attachment gone; the tooth is usually non-salvageable

Dog tooth decay at stage 4 is the one most owners arrive searching for, because it is the first stage that is unmistakable across the room. It is also painful, and dogs hide dental pain extremely well — eating normally is not evidence that a mouth is comfortable.

What you are actually looking at right now

Most people reading this are holding a phone in one hand and lifting a lip with the other. Here is how to interpret what is in front of you.

If you see a thin yellow haze and a red line at the gum

This is the mild end — the picture that matches gingivitis. The enamel still looks mostly clean, but there is a dull film where tooth meets gum, and the gum margin is a brighter red than the tissue above it. It may bleed a little after a chew. This is the stage where daily brushing and a professional cleaning make the biggest difference, and it is worth booking a veterinary dental exam now rather than in six months.

If you see hard brown build-up and puffy gums

The crust no longer wipes away. It is thickest on the upper fourth premolar — the big carnassial tooth behind the canine — because the salivary duct opens nearby. Gums look swollen and rolled. Breath is noticeably off. This usually corresponds to stage 2 or 3, and at-home products will not remove mineralised calculus; only scaling under anaesthesia will.

If you see a grey, pink, purple or fractured tooth

Colour change in a single tooth means something happened to the pulp inside it, often a fracture from a bone, antler or hard nylon chew. A slab fracture on a carnassial tooth may show a flat chip with a dark line. A discoloured tooth is usually a dead tooth, and dead teeth become abscesses. This warrants a veterinary appointment regardless of how the rest of the mouth looks.

If you see exposed roots, pus or a loose tooth

This is the advanced picture. Gums have receded far enough that the narrower, yellower root surface is visible; there may be a dark gap between two roots on a molar, a bead of pus when the gum is pressed, or a tooth you can rock with a fingertip. Facial swelling below the eye points to a tooth-root abscess. These dogs need veterinary attention promptly, not at the next annual visit.

What before-and-after photos actually show

The dramatic cleaning photos circulating online show calculus removal — the cosmetic half of the story. What they cannot show is bone level, which is why two mouths that look identical after scaling can have completely different prognoses. Tooth decay in dogs is diagnosed under anaesthesia with full-mouth dental X-rays, and what you can see above the gumline is usually the smallest part of the problem.

What causes dog tooth decay

Plaque is the root cause. Bacteria colonise the tooth surface within hours of cleaning, form a biofilm, and mineralise into calculus within days. The calculus is not itself the villain — it is a rough scaffold that holds more plaque against the gum, and the immune response to that plaque is what destroys bone and ligament.

Several factors accelerate it:

• Breed and skull shape. Small and brachycephalic breeds crowd a full set of teeth into a short jaw, trapping plaque between rotated teeth.
• Age. Accumulation is cumulative, so disease stage tends to climb with each year.
• Diet and chewing habits. Soft food leaves more residue; excessively hard chews cause the fractures that open teeth to infection.
• Genetics and immune response. Two dogs with the same plaque load can show very different levels of bone loss.
• Lack of home care. Brushing disrupts the biofilm before it mineralises; nothing else matches it.

What a veterinary dental does at each stage

Treatment follows the stage. Gingivitis is managed with professional scaling and polishing plus a realistic home-care routine. Early and established periodontitis may add root planing, local antibiotic gel placement into pockets, or periodontal surgery to preserve a strategically important tooth. Stage 4 teeth are usually extracted, because leaving a mobile, infected tooth in place leaves a source of chronic pain and bacterial load.

Anaesthesia is not optional for any of this. Anaesthesia-free scaling cleans the visible crown and leaves the diseased pocket untouched, which is the part that matters. Your veterinarian will run pre-anaesthetic bloodwork, X-ray the whole mouth, and give you a treatment plan based on what the films show — and that plan, not an internet chart, is the thing to follow.

Recovery support for the senior dog behind the mouth

A dog with stage 3 or 4 dental disease is usually a dog who has been quietly uncomfortable for a long time, and quiet discomfort shows up elsewhere: less play, stiffer rising, shorter walks. Dental work fixes the mouth. It does not fix the deconditioning, the stiff hips, or the soft-tissue niggles that built up while the dog was slowing down.

That recovery window is where pawgen's K9-REPAIR fits. It is a BPC-157 and TB-500 peptide formulation made for dogs, dosed by body weight and third-party tested with COAs published for every batch. BPC-157 is a peptide studied for its role in angiogenesis and soft-tissue and tendon repair signalling; TB-500 is related to thymosin beta-4, which research links to cell migration and tissue remodelling. Owners report using the two together through post-procedure and post-injury periods as their dog rebuilds condition. These are not FDA-approved veterinary drugs, the science is emerging and promising rather than settled into label claims, and nothing here is a substitute for the dental treatment or pain relief your veterinarian prescribes — talk to your veterinarian before adding anything while your dog is recovering from a procedure.

Key Takeaways

• Dog tooth decay most often looks like yellow-brown tartar at the gumline, red inflamed gums, receding tissue and, later, loose or discoloured teeth.
• True cavities are uncommon in dogs; periodontal disease is the real driver of tooth loss.
• Stages run from gingivitis (reversible inflammation) to stage 4, where more than half the tooth's attachment is gone.
• Plaque causes it, tartar reveals it, and only anaesthetised scaling plus dental X-rays can stage it accurately.
• A single grey, pink or fractured tooth is worth a veterinary visit on its own.
• Daily brushing remains the most effective home measure available to any owner.

Your veterinarian owns the diagnosis, the X-rays and the treatment plan — the staging, extractions and pain management all belong in their hands, and this article is background reading, not a substitute for that exam. Supplements and peptides operate in the space that proper veterinary care creates: once the infection is addressed and the pain is controlled, the job becomes rebuilding a dog who has been running on reduced output for months.

You can review third-party certificates of analysis for every batch at /coas/, see the full K9-REPAIR formulation at /shop/, check shipping availability at /location/, or read more at pawgen.

Owners exploring peptide support for their dog can review K9-REPAIR — BPC-157 + TB-500 formulated for dogs — at https://pawgen.com/. BPC-157 and TB-500 are not FDA-approved veterinary drugs. Nothing in this article treats, cures or prevents any condition; every decision about your dog's care belongs with your veterinarian.