Tooth decay in dogs is a disease in which acids demineralize calcified tooth tissues, exposing the inner structures. Tooth decay in dogs is known as caries and cavities. 

Bacteria build-up ferments the carbohydrate-based food trapped in a dog’s tooth, causing tooth decay. The fermented bacteria produce acids that demineralize the enamel on the teeth, exposing its matrix and resulting in decay. Dog teeth anatomy, oral biome, saliva properties, and dietary habits mean caries are uncommon in dogs. 

Labrador Retrievers, German Shepherds, Chihuahuas, and most brachycephalic breeds, such as Shih Tzus, are at a higher-than-average risk of developing tooth decay. Poor dental hygiene and feeding table scraps increase the chances of decay. 

Tooth decay in dogs symptoms are bad breath, discolored teeth, swollen or bleeding gums, pain or sensitivity, reduced appetite, drooling, loose or missing teeth, and behavioral changes. 

The vet diagnoses rotting dog teeth through oral inspection. An oral X-ray is recommended to assess the extent of the decay fully.  Avoid feeding dogs highly refined and easily fermentable carbohydrates to prevent tooth decay.

The treatment of dog tooth decay depends on the severity of the defect. Early dog tooth decay stages are managed with fillings, and more advanced forms require root canal surgeries or tooth removals. 

What is Tooth Decay in Dogs?

Tooth decay in dogs is a condition affecting the calcified teeth tissues. The issue occurs when microorganisms ferment carbohydrates. 

The dog’s teeth have smooth surfaces, pits, and fissures. Food carbohydrates accumulate on the smooth surfaces or get trapped in the pits and fissures. 

Cariogenic bacteria, normally present in the oral cavity, ferment carbohydrates. The fermentation produces destructive acids, which decalcify the inorganic part of the tooth and disintegrate the organic part. 

Dog tooth decay is classified by location, including smooth surface caries, root surface carries, and pit or fissure caries. 

Pit and fissure cavities are the most common, with risk locations being the upper jaw’s fourth premolar and first molars and the lower jaw’s first molars. 

What are the other terms for Tooth Decay in Dogs?

The other terms for tooth decay in dogs are caries, cavities, and rotting. Caries is the most commonly used term for tooth decay. The name is derived from Latin, and its direct translation is “rottenness.” The dogs teeth rotting causes defects or cavities, hence the other name of the condition. Cavities are small holes in the tooth caused by bacterial build-up. 

How does Tooth Decay in dogs differ from other Dental Diseases in Dogs?

Tooth decay in dogs differs from other dental diseases in dogs in incidence and etiology. Cavity is  rare in dogs, while periodontal (gum) disease is widespread. 

Caries develop when bacteria produce acids that destroy the enamel of the teeth. Other dental diseases, such as gingivitis or gum disease, occur when plaque and tartar build-up on the teeth. 

Pet owners find it hard to differ dental disease in dogs from tooth decay. Bad breath is an early universal sign of dental problems. 

How does Tooth Decay in Dogs develop?

Tooth decay in dogs develops when cariogenic bacteria demineralize the dental surface, called enamel. The condition occurs at any age but is more common in older dogs.  

Bacteria in the dog’s mouth ferment carbohydrates from food, releasing acetic, lactic, and propionic acid. The acids penetrate and demineralize the tooth enamel, exposing its matrix. 

The process progresses and affects the dentin and pulp, forming significant defects. The defects expand, coalesce, and collapse the undermined enamel. 

The enamel and the oral fluid containing bacteria are constantly exchanging minerals. Mineral exchange is balanced in healthy dogs. 

The mineral exchange is imbalanced, and the enamel loses structural minerals is the answer to the “Why are my dogs teeth rotting?” question.

How common is Tooth Decay in Dogs?

Tooth decay in dogs is not common. Cavity affects 5% of the dog population, reports Dr. Fraser Hale in a post “Dental Caries in Dogs” for DentalVets. 

“Dental caries, or bacterial infections of the teeth, are common in humans, uncommon in dogs, and essentially nonexistent in cats,” according to Brenda L. Mulherin, DVM, in an article “Dental Caries in Small Animals” published in MSD Manual in 2024. 

Tooth decay is less frequent in dogs than in humans because of the conical shape of dog teeth and the wide space between the teeth. Dogs eat low-carb foods, have high saliva pH, and low amylase levels in the saliva. 

What breeds are more prone to developing Tooth Decay?

The breeds that are more prone to developing tooth decay are listed below.

• Labrador Retrievers: Labrador Retrievers are a large dog breed susceptible to tooth decay due to their increased tendency to dietary indiscretions. 
• German Shepherds: German Shepherds develop caries in the pits and flat masticatory surfaces of the first molars of the upper (maxilla) jaw.
• Chihuahuas: Chihuahuas have very small oral cavities and crowded teeth, putting them at a high risk of developing tooth decay. 
• Shih Tzus: Shih Tzu teeth rotting is common because brachycephalic breeds have irregularly lined teeth prone to trapping food. 

What does Tooth Decay in Dogs look like?

Tooth decay in dogs looks like easily visible black dark spots or deep holes in the teeth. The teeth have a yellowish-to-brownish discoloration, most striking at the gum line. The gums are inflamed, and the line between the teeth and gum features signs of plaque and tartar buildup.  

What are the Causes of Tooth Decay in Dogs?

The causes of tooth decay in dogs are listed below. 

• Cariogenic Bacteria: The dog’s oral microbiome does not contain the primary decay-causing cariogenic germ, like Streptococcus mutans, but the bacterium is transmissible from humans to dogs, says a study, “Evidence Supporting Oral Hygiene Management by Owners through a Genetic Analysis of Dental Plaque Bacteria in Dogs,” issued in Veterinary Sciences in 2024.  
• Interdental Spacing: Crowded teeth trap food and cause cavities. Shih Tzu’s and brachycephalic breeds have crowded teeth. The space between dog teeth is typically wide and does not trap food. 
• Dietary Indiscretions: The natural canine diet is low in carbohydrates. Dogs fed table scraps develop tooth decay. “A diet high in highly refined and easily fermentable carbohydrates favors the development of caries,” explains a study, “Dental Caries in the Dog,” published in the Canadian Veterinary Journal in 2009.   
• Poor Dental Hygiene: Tooth decay in dogs is caused by poor dental hygiene. Brushing the dog’s teeth helps remove accumulated food before it starts to ferment and release cavity-causing acids. 

What are the Symptoms of Tooth Decay in Dogs?

The symptoms of tooth decay in dogs are listed below. 

• Bad Breath: Bad breath, or halitosis, is an early sign of tooth decay, which stems from the rotting processes on the surface of the teeth. 
• Discolored Teeth: Prolonged tooth decay combined with plaque and tartar buildup causes discoloration of the teeth. 
• Swollen or Bleeding Gums: Gum swelling and bleeding are typical signs of inflammation associated with dental problems. 
• Pain or Sensitivity: The defects on the surface of the teeth progress into the deeper layers, leaving the inner structures exposed and sensitive. 
• Reduced Appetite: Dogs with tooth decay are reluctant to eat because the dental condition is painful. 
• Drooling: Diseases of the teeth and gums predispose dogs to excessive saliva or drooling. 
• Loose or Missing Teeth: Tooth decay is a progressive condition that culminates in tooth loss. The teeth get loose and then fall out or are surgically removed. 
• Behavioral Changes: The pain and discomfort associated with oral problems in dogs trigger behavioral changes, such as irritability, lethargy, or disinterest in daily activities. 

1. Bad Breath

Bad breath is an unpleasant smell radiating from a dog’s mouth, a telltale sign of an underlying oral condition. The medical term for bad breath is halitosis. 

Dogs with tooth decay have bad breath as an early symptom. Halitosis is caused by increased food fermentation and rotting processes in the mouth. Bad breath is a nuisance for owners. 

2. Discolored Teeth

Discolored teeth in dogs are teeth that turn from white to yellow, brown, or grey. The loss of whiteness is an indicator of tooth disease. 

Rotting teeth become brownish and are covered in plaque. The plaque varies in color, but it is generally dark. A dog with discolored teeth requires prompt veterinary attention. 

3. Swollen or Bleeding Gums

Swollen or bleeding gums are signs of inflammation. Inflammatory conditions in the dog’s mouth are painful and harm its quality of life. 

Tooth decay does not affect the dog’s gums directly. The bacteria, however, are associated with cavities and damage the gums. Swelling and bleeding are the gum’s responses to inflection. 

4. Pain or Sensitivity

Pain or sensitivity is increased discomfort sensation. Dogs with tooth decay are in pain when caries advance. 

Tooth decay spreads from the enamel to the dentin and the pulp chamber. Pain occurs when the pulp chamber is open, and the nerve is exposed. The pain impacts the dog’s daily habits. 

5. Reduced Appetite

Reduced appetite is decreased interest in food. A complete loss of appetite is called anorexia and is a common symptom of tooth decay. 

Cavities are painful, especially if the defect affects the tooth's pulp. The pain deters the dog from eating. Dogs approach the food bowl and pick up food but spit it out as soon as the exposed pulp reacts. 

6. Drooling

Drooling is an increased saliva production. The condition is medically known as hypersalivation and is frequent in dogs with decayed teeth. 

The dog’s teeth are a barrier that keeps saliva inside the mouth. Tooth decay affects the role and structure of the dental barrier. Drooling is not a specific sign of tooth decay and requires veterinary attention. 

7. Loose or Missing Teeth

Loose or missing teeth are unstable or absent from the dog’s mouth. The issues are seen in dogs with advanced tooth decay stages. 

Caries are progressive in dogs. The decay starts from the enamel and spreads to the deeper structures and crowns. Defects in the tooth crown are destabilizing and lead to loose or missing teeth. 

8. Behavioral Changes

Behavioral changes in dogs refer to unusual conduct. Behavioral changes accompany many conditions and are always a reason to see a veterinarian. 

Dogs with tooth decay become moody and easily irritable. The painful nature of caries triggers the behavioral changes. Dogs become disinterested in daily activities and withdraw for no apparent reason. 

When does Tooth Decay in Dogs Symptoms usually occur?

Tooth decay in dogs symptoms usually occurs when the condition is advanced. The early sign, bad breath, is universal and often overlooked. 

Owners notice tooth decay symptoms when the dog’s appetite declines. Dogs with caries are in pain and reluctant to consume food. Some dogs go to the food bowl and attempt to eat but are deterred by the pain. 

How does a dog's mouth structure affect tooth decay?

The dog’s mouth structure affects tooth decay by reducing its incidence. Tooth decay is far less common in dogs than in humans. 

Dogs have conical teeth and larger interdental spaces that do not support food accumulation. The canine saliva has a high pH and little amylase. 

Microorganisms in the dog’s mouth have an antagonistic effect on cariogenic bacteria, such as S. mutans, suggests a study, “Antagonism of Bacteria from Dog Dental Plaque against Human Cariogenic Bacteria,” published in Biomed Research International in 2018. 

Tooth decay negatively affects the dog mouth structure, resulting in large defects and tooth loss. 

What are the Risk Factors of Tooth Decay in Dogs?

The risk factors of tooth decay in dogs are listed below. 

• Age: Canine tooth decay occurs at any age, but older dogs are more susceptible because of declining oral health. 
• Tooth Anatomy: The risk of dog cavity increases on teeth with more pronounced and deep pits and fissures.  
• Table Scraps: Feeding sugary foods rich in readily fermentable carbohydrates, such as table scraps, increases the risk of tooth decay in dogs. 
• Lack of Hygiene: Poor dental hygiene, which allows food to build up on the tooth’s surface, pits, and fissures, is a major risk factor for developing dog cavities. 
• What are the risks of untreated tooth decay in dogs?

The risks of untreated tooth decay in dogs are listed below. 

• Severe Recurring Pain: Tooth decay is painful. The severity of the pain is variable, but it is chronic or recurring and debilitates the dog if untreated. 
• Difficulty Chewing: Cavities cause chronic pain and impair chewing. Improper food chewing harms digestion and nutrient absorption when left untreated. 
• Chipped or Broken Teeth: The defects caused by tooth decay undermine the integrity of the tooth structure and lead to chipping and breaks. 
• Tooth Loss: The culmination of caries in dogs is tooth loss. Dogs lose teeth prematurely when tooth decay is untreated. Early tooth loss harms the dog’s quality of life.

What are the complications of Tooth Decay in dogs?

The complications of tooth decay in dogs are listed below. 

• Bad Breath: Bad breath or halitosis accompanies tooth decay in dogs. The issue does not affect dogs but is unpleasant for the owners. 
• Abscess Development: Caries cause abscesses in the dog’s mouth, usually on the root of the teeth. An abscess is a pus-filled pocket caused by bacterial infections. 
• Gum Disease: Periodontal or gum disease is supported and aggravated by tooth decay in dogs, contributing to further tooth loss. 
• Tooth Sensitivity: The defects caused by the cavity expose the inner structures of the teeth and the inner pulp chamber and cause pain. 
• Irritability: The tooth decay pain makes dogs irritable and prone to unprovoked snappiness and sudden mood swings.  

How is Tooth Decay in Dogs diagnosed?

Tooth decay in dogs is diagnosed with an oral inspection. A veterinarian  sees cavities by inspecting a dog's mouth.

Anesthetizing the dog is necessary for a more thorough evaluation. The vet probes the painful spots and checks for co-existing dental conditions. 

The final step is taking an X-ray of the affected teeth. The X-ray shows the extent of the problem, which is critical for making the right treatment decision. 

Where can you seek a diagnosis for Tooth Decay in dogs?

You can seek a diagnosis for tooth decay in dogs at the vet. Caries are often diagnosed in general checkups. 

General veterinary practitioners see tooth decay regularly and  make a diagnosis. The vet, however, refers specific cases of cavities to veterinary dentists who diagnose and treat tooth decay. 

What are the treatments for Tooth Decay in dogs?

The treatments for tooth decay in dogs are listed below. 

• Fillings: Moderate cases of decay are managed by debridement and defect restoration. The veterinarian removes the carious dentine using special dental burs or sharp spoon excavators. The defect is restored with a filling. 
• Root Canal: Root canal surgery is required for severe tooth decay where the pulp is exposed. The vet debrides the rotten part of the tooth and removes the diseased pulp and nerve. The space is filled and sealed with inert material.  
• Extraction: Teeth decayed beyond repair are surgically removed because rotten teeth are challenging to extract. 
• Antibiotics: The veterinarian prescribes antibiotics to manage or prevent oral bacterial infections after the dog tooth decay treatment.