Small dogs do get more gum disease than big dogs, and by a wide margin. In UK vet records for 22,333 dogs, those under 10 kg (22 lb) had about three times the odds of a periodontal disease diagnosis compared with dogs weighing 30 to 40 kg (O'Neill and colleagues, 2021). The main reason is anatomy. A Chihuahua has the same 42 adult teeth as a Labrador, packed into a jaw a fraction of the size.
It also starts younger than most owners expect, often before the first birthday, and on the front teeth rather than the big back ones. The first stage, gingivitis, is inflamed gums, and it can still be reversed. Once it becomes periodontitis, the lost support doesn't grow back. So a small dog's routine has to start sooner and run more often.
How much more gum disease small dogs get
The clearest numbers come from VetCompass, a Royal Veterinary College project that reads anonymized UK vet records. In 22,333 dogs seen in 2016, one in eight was diagnosed with periodontal disease that year, and the share fell with every step up in adult weight.
| Adult weight | Diagnosed in one year | Odds vs 30 to 40 kg |
|---|---|---|
| Under 10 kg (22 lb) | 20.6% | 3.07 |
| 10 to 15 kg | 18.6% | 2.48 |
| 15 to 20 kg | 12.9% | 1.50 |
| 20 to 25 kg | 12.1% | 1.29 |
| 25 to 30 kg | 11.3% | 1.23 |
| 30 to 40 kg | 9.9% | 1.00 |
| 40 kg and over | 6.2% | 0.58 |
Shares calculated from the case counts in O'Neill and colleagues (2021), for the 17,277 dogs with a recorded adult weight. Odds from their model, which allowed for age, sex, neutering and insurance.
In over 3 million US hospital records, extra-small breeds under 6.5 kg (14 lb) were up to five times more likely to be diagnosed than giant breeds, and age, extra weight and a long gap since the last cleaning added to it (Wallis and colleagues, 2021). These are diagnoses written in a record, so they undercount. Exams under anesthesia find far more. Read the table as a comparison between sizes, not as your own dog's chance.
The same 42 teeth in a smaller jaw
Teeth don't shrink in step with the dog. In a small breed they stay large for the jaw, so they crowd, overlap and rotate, and every tight corner holds plaque that a tongue or a chew can't reach. The 2019 AAHA dental guidelines say any puppy expected to weigh under 20 to 25 lb as an adult is likely to need more involved dental care than a larger dog. On X-rays, the lower first molar is proportionally taller against the jawbone in small dogs (Gioso and colleagues, 2001). Those tight corners are also part of why tartar can build up so fast on a small dog's teeth. Saliva and age play a part too, as our page on why some dogs build more tartar explains.
A baby tooth that hangs on beside its adult replacement adds one more trap to a jaw that is already full. Small dogs keep them more often than most. In US hospital records, 15% of extra-small breeds had at least one, about twice the rate across all dogs (Wallis and colleagues, 2024). Our puppy teething timeline shows when each baby tooth should be gone, and what to do if one isn't.
Then there is the bone. A small dog has very little jawbone around the roots of that big molar, so the bone gum disease eats away is a bigger share of what holds the jaw together. One case series described six dogs, mostly older small dogs, three under 4 kg (9 lb), whose lower jaws broke, most just in front of the first molars. In five, a fall, a fight or a car broke a jaw already thinned by advanced periodontal disease (Carvalho and colleagues, 2015). In a jaw that weak, the authors note, mild trauma, an extraction or simply eating can be enough.
It starts before the first birthday
The youngest mouths studied belonged to a colony of Yorkshire terriers at the Waltham Centre for Pet Nutrition (now the Waltham Petcare Science Institute), which Mars owns, so read it as industry research. Each dog was examined tooth by tooth under anesthetic from 37 weeks of age, about 8 and a half months. At that first check, 48 of 49 already had early periodontitis in at least one tooth, and 30.5% of all their teeth were affected (Wallis and colleagues, 2019). Nearly every affected tooth was at stage 2, the first stage of periodontitis, which is explained with the others in our guide to how gum disease is staged.
The canine teeth were the most likely to be affected, then the incisors at the front. The litter mattered too, with the average share of affected teeth ranging from 15.8% in one litter to 55.3% in another, which points to inherited risk. And brushing was hard. These Yorkies rarely let anyone brush the whole mouth, the brushed dogs showed no measurable difference, and brushing was dropped from the study.
Miniature Schnauzers show the speed. When 52 adults had their tooth care stopped, 35 had at least 12 teeth turn from gingivitis to periodontitis within 60 weeks, and only one dog had none. Over half of those teeth were incisors, with the tongue side most affected (Marshall and colleagues, 2014). The authors recommend vet dental checks twice a year from a young age for breeds like this. Labradors in a similar study got there later, with 56.6% affected over two years (Wallis and colleagues, 2018). In the Schnauzers and the Labradors it began on the tongue side of the front teeth, where an owner lifting the lip doesn't look, so a mouth that looks clean isn't proof.
Breeds that carry the most risk
In the UK records, 18 breeds had raised odds of a diagnosis compared with crossbreds, after allowing for age, sex and other factors. Most are toy and small breeds.
| Breed | Odds vs crossbreds |
|---|---|
| Toy Poodle | 3.97 |
| King Charles Spaniel | 2.63 |
| Greyhound | 2.58 |
| Cavalier King Charles Spaniel | 2.39 |
| Lhasa Apso | 2.24 |
| Yorkshire Terrier | 2.16 |
| Cockapoo | 2.11 |
| Chihuahua | 2.09 |
| Miniature Dachshund | 1.80 |
| Bichon Frise | 1.67 |
| Miniature Schnauzer | 1.66 |
| West Highland White Terrier | 1.47 |
| Jack Russell Terrier | 1.37 |
Selected breeds from O'Neill and colleagues (2021).
The Greyhound is the odd one out, a large, lean dog sitting among the toy breeds, so its owners should treat the mouth like a small dog's.
Some small breeds didn't stand out. The Shih Tzu and the Pug were close to crossbreds, and the French Bulldog had less than half their odds. The authors think the French Bulldog result may be real, but they also suggest that worries about anesthesia in the breed may mean fewer routine dental checks, so fewer cases get written down. Flat-faced dogs as a group still came out slightly worse than dogs with a medium-length face, so if you have one, use the small-dog routine anyway.
Breeds with their own guide
Each of these breeds has a page of its own. The figure here is the one that stands out for the breed, and the guide explains what it means day to day.
| Breed | What stands out | Guide |
|---|---|---|
| Toy Poodle | The highest odds of any breed in the UK records | Poodle teeth problems |
| Yorkshire Terrier | Gum disease was the top diagnosis, in 21.1% of 3,308 Yorkies in one year | Yorkie teeth problems |
| Chihuahua | Stuck baby teeth before age 2, then gum disease in one in three dogs over 7 | Chihuahua teeth problems |
| Miniature Dachshund | A thin wall of bone between the upper canine root and the nose, and 3.3 times the fistula risk of similar small dogs | Dachshund teeth problems |
| Pomeranian | Missing from the UK records, but about twice the odds of mixed breeds in a 2026 US and Canada owner survey | Pomeranian teeth problems |
| Maltese | Baby teeth often start to fall out late, closer to 5 months than the usual 3 and a half | Maltese teeth problems |
| Shih Tzu | Close to crossbreds in the UK records, with an underbite written into the breed standard | Shih Tzu teeth problems |
| Pug and French Bulldog | Pugs kept a baby tooth in 5.5% of UK records, against 1.0% of other dogs | French Bulldog and Pug teeth problems |
| Greyhound | A large breed with toy-breed odds | Greyhound teeth |
A routine sized for a small dog
For a toy or small breed, the schedule matters as much as the method.
- By 7 months, every baby tooth should be gone. If a baby canine is still there next to the adult one, book the vet rather than waiting for it to drop out.
- Once the adult teeth are in, brush daily. Plaque can harden into tartar within days, so twice a week leaves gaps. Our step-by-step guide to brushing a dog's teeth covers small brushes and reluctant dogs.
- Once a week, lift the lip and look at the front teeth and canines as well as the back teeth.
- Book the first full cleaning under anesthesia, with X-rays, before your dog's first birthday. That's AAHA's advice for small dogs, and our dental cleaning guide walks you through the day.
- After that, have the mouth checked every 6 to 12 months, as your vet advises for your dog. Many small dogs need a cleaning every year, some more often.
Small dogs often won't sit still for a full brushing, as the Yorkie study found. Start with the front teeth and canines, where the Yorkies' disease began, and add a few teeth at a time. Chews must be sized for the dog, because a small dog that gulps one can get it stuck in the esophagus, and soft enough to dent with a thumbnail. A food topper suits a small, picky eater that won't take a chew. At best a topper or a chew slows new plaque and tartar. Neither replaces the cleaning under anesthesia, and cleaning without anesthesia can't reach below the gumline.
When to see the vet sooner
In a small dog, a few signs mean booking the vet before the yearly check. A loose front tooth matters, because that's where small dogs' gum disease tends to start. So does a runny nose on one side, which can come from gum disease around an upper tooth whose root sits close to the nose. And a baby tooth still in place after 7 months needs a vet to look at it. Other signs of gum disease, from bleeding gums to a swollen face, are worth a call too.
If your small dog cries out, can't close its mouth or its jaw looks uneven after a knock or even after eating, go to the vet the same day. With advanced gum disease, the lower jaw can break with very little force.
Toppers and supplements aren't for every small dog. Ask your vet before adding one if your dog is pregnant, is still a young puppy, or has thyroid or kidney trouble.
Common questions
Is it normal for small dogs to have bad teeth? It is common, not normal. About one in five UK dogs under 10 kg was diagnosed with periodontal disease in a single year. Gingivitis can be reversed, which is why the routine should start young.
Which dog breeds have the worst teeth? In UK vet records the Toy Poodle had nearly four times the odds of crossbreds, followed by the King Charles Spaniel, the Greyhound and the Cavalier King Charles Spaniel (O'Neill and colleagues, 2021).
At what age should a small dog have its first dental cleaning? By 1 year old, under anesthesia with X-rays, according to the 2019 AAHA guidelines. Larger dogs can wait until 2.
How often should a small dog have its teeth cleaned at the vet? Usually a check every 6 to 12 months and a cleaning at least once a year, as your vet sets it. For fast-affected breeds like the Miniature Schnauzer, researchers suggest checks twice a year.
References
- Bellows J, Berg ML, Dennis S, et al. 2019 AAHA Dental Care Guidelines for Dogs and Cats. Journal of the American Animal Hospital Association 2019;55(2):49-69. doi:10.5326/JAAHA-MS-6933.
- Carvalho CM, Rahal SC, Mesquita LR, Castilho MS, Kano WT, Mamprim MJ. Mandibulectomy for treatment of fractures associated with severe periodontal disease. Canadian Veterinary Journal 2015;56(3):292-294. PMID 25750452.
- Gioso MA, Shofer F, Barros PS, Harvey CE. Mandible and mandibular first molar tooth measurements in dogs: relationship of radiographic height to body weight. Journal of Veterinary Dentistry 2001;18(2):65-68. PMID 11968914.
- Marshall MD, Wallis CV, Milella L, et al. A longitudinal assessment of periodontal disease in 52 Miniature Schnauzers. BMC Veterinary Research 2014;10:166. doi:10.1186/1746-6148-10-166.
- O'Neill DG, Mitchell CE, Humphrey J, Church DB, Brodbelt DC, Pegram C. Epidemiology of periodontal disease in dogs in the UK primary-care veterinary setting. Journal of Small Animal Practice 2021;62(12):1051-1061. doi:10.1111/jsap.13405.
- Wallis C, Patel KV, Marshall M, et al. A longitudinal assessment of periodontal health status in 53 Labrador retrievers. Journal of Small Animal Practice 2018;59(9):560-569. doi:10.1111/jsap.12870.
- Wallis C, Pesci I, Colyer A, et al. A longitudinal assessment of periodontal disease in Yorkshire terriers. BMC Veterinary Research 2019;15:207. doi:10.1186/s12917-019-1923-8.
- Wallis C, Saito EK, Salt C, Holcombe LJ, Desforges NG. Association of periodontal disease with breed size, breed, weight, and age in pure-bred client-owned dogs in the United States. The Veterinary Journal 2021;275:105717. doi:10.1016/j.tvjl.2021.105717.
- Wallis C, Ivanova A, Holcombe LJ. Persistent deciduous teeth: association of prevalence with breed, breed size and body weight in pure-bred client-owned dogs in the United States. Research in Veterinary Science 2024;169:105161. doi:10.1016/j.rvsc.2024.105161.