Why Do Small Dogs Have Such Terrible Teeth? A Vet Explains
By Dr Joe Inglis BVSc MRCVS ·
Why do small dogs have worse teeth than big dogs? Discover why breeds like Poodles, Shih Tzus and Chihuahuas are more prone to dental disease.
I was out for dinner with some friends recently, and the conversation turned to dogs and what we're doing at Luna.
One of my friends has two small dogs and has owned Poodles, Havanese and Shih Tzus throughout her life. She was telling me how much dental work her dogs have needed over the years, including multiple teeth being removed.
Meanwhile, another friend with a Labrador mentioned that he'd never really had any problems with his dog's teeth.
Which led to a really interesting question.
Why do small dogs seem to have such terrible teeth compared with bigger dogs?
And believe it or not, there's actually quite a bit of science behind this.
Are Small Dogs Really More Prone to Dental Disease?
Yes, and the research is pretty convincing.
A major Royal Veterinary College study published in 2021 looked at veterinary records from more than 22,000 dogs across the UK.
Researchers found that dogs weighing under 10 kg had more than three times the adjusted odds of periodontal disease compared with dogs weighing between 30 and 40 kg.
Periodontal disease, commonly known as gum disease, is an infection and inflammation of the tissues supporting your dog's teeth. Left untreated, it can damage the gums and surrounding bone, eventually leading to tooth loss.
And the breed findings were just as interesting.
Toy Poodles had almost four times the adjusted odds of periodontal disease compared with the crossbred reference group, even after accounting for other factors such as age.
Labrador Retrievers, on the other hand, had significantly lower recorded odds of gum disease than crossbred dogs.
So my friends' experiences weren't entirely surprising.
But why does this happen?
1. Small Dogs Have a LOT of Teeth in Tiny Mouths
Here's something that surprises many dog parents.
A Chihuahua and a Great Dane normally have the same number of adult teeth. 42
Think about that for a moment.
A tiny Chihuahua weighing 3 kg has to accommodate the same number of teeth as a Great Dane weighing 60 kg.
And while the teeth themselves are smaller, they're proportionally much larger relative to the size of the jaw.
This means small dogs can end up with overcrowded, overlapping or poorly positioned teeth.
The problem? When teeth are packed tightly together, there are more little spaces where plaque and bacteria can accumulate.
And those areas can be incredibly difficult to clean, even if you're brushing regularly.
This is particularly relevant for breeds like Toy Poodles, Yorkshire Terriers and Chihuahuas.
2. Their Jawbones Are Smaller, Too
This is something I think more dog parents should understand.
It's not just about how many teeth fit inside a dog's mouth. It's also about the bone supporting them.
Small dogs have much smaller jawbones, and their teeth can take up a relatively large proportion of that bone.
When periodontal disease develops, the infection and inflammation can gradually damage the bone surrounding the tooth roots.
For a very small dog, losing that supporting bone can become particularly serious.
In advanced cases, there may be so little healthy bone remaining that the jaw becomes vulnerable to fracture.
This is one reason we take dental disease in small dogs so seriously at Luna.
It's not simply about cleaning brown tartar off their teeth. We're also concerned about what's happening underneath the gumline.
3. Some Small Dogs Don't Lose Their Puppy Teeth
Have you ever noticed a small dog with what looks like two teeth growing in the same place?
This is called a retained puppy tooth, and it's something we see particularly in smaller breeds.
Normally, a puppy's baby teeth fall out as their adult teeth grow in.
But sometimes a baby tooth refuses to budge.
The adult tooth then grows alongside it, leaving two teeth crowded into a space that's really only meant for one.
And as you can imagine, that creates even more places for plaque and bacteria to build up.
A 2023 study involving 61 Yorkshire Terrier puppies found that 69% had retained puppy teeth.
That's a surprisingly high number.
Our advice: If your puppy has adult teeth growing alongside their baby teeth, have them checked by a vet. Retained puppy teeth may need to be removed to prevent problems developing later.
4. The Shape of Their Face Can Make Things Worse
It's not just the size of the dog that matters. The shape of their skull and jaw plays a role, too.
Take a Shih Tzu, for example.
Shih Tzus have relatively short muzzles, which can make it more difficult for their teeth to fit into their normal positions.
Some teeth may become crowded, rotated or overlap.
And the harder those teeth are to clean, the easier it can be for plaque to accumulate.
In fact, the RVC study found that flat-faced dogs had approximately 25% higher adjusted odds of periodontal disease than dogs with medium-length skulls.
Of course, not all small dogs have short faces. But it's another reason certain breeds may be more vulnerable to dental problems.
5. Genetics May Also Play a Role
Here's where things get even more interesting.
Two dogs of the same size can have very different dental health.
One might develop significant gum disease at a relatively young age, while another could have much healthier teeth for years.
Why?
We know that breed and inherited characteristics can affect how likely a dog is to develop gum disease.
Differences in jaw anatomy, tooth positioning and potentially the way a dog's immune system responds to oral bacteria may all play a role.
But there's still a lot we don't fully understand about the genetic side of canine dental disease.
The important thing to remember is that being predisposed doesn't mean gum disease is inevitable.
Regular dental care can make a big difference.
So Why Do Bigger Dogs Often Have Better Teeth?
Going back to my friend with the Labrador.
Larger dogs generally have more room in their jaws for their teeth, which can reduce some of the crowding problems we see in smaller breeds.
The RVC research also found that larger dogs had lower odds of periodontal disease.
But that doesn't mean Labradors and other big dogs are immune.
They can still develop gum disease, fractured teeth, infections and other dental problems.
What Can Small-Dog Parents Do to Protect Their Dog's Teeth?
If you own a Poodle, Havanese, Shih Tzu, Chihuahua or another small breed, please don't assume your dog is destined to lose their teeth.
There are some simple things you can do to help.
Start brushing early. Ideally, brush your dog's teeth every day using a soft pet toothbrush and toothpaste formulated for dogs. If your dog isn't used to brushing, start slowly and build up their confidence.
Don't overlook their puppy teeth. If you notice adult teeth growing alongside baby teeth, have your vet take a look.
Pay attention to their gums. Persistent bad breath, red or bleeding gums, tartar and loose teeth are all reasons to arrange a dental check.
Arrange regular dental examinations. Small breeds may need more frequent professional dental care than larger dogs. We can help determine what's appropriate for your dog at Luna.
And remember, once plaque has hardened into tartar, brushing alone won't remove it.
We've also put together a complete guide to dog dental disease, including the symptoms to look out for and when treatment might be needed.
What Are We Seeing at Luna?
Our own dental records at Luna reveal some interesting trends, too.
Miniature Schnauzers have stood out for the number of teeth requiring extraction, with Yorkshire Terriers, Chihuahuas, Jack Russell Terriers and Pomeranians also featuring prominently.
While our findings reflect dogs already receiving dental treatment rather than the wider UK dog population, they offer another interesting perspective on just how important dental care is for smaller breeds.
Does Your Small Dog Need a Dental Check?
One thing I always remind dog parents is that small dogs may need a little extra attention when it comes to their teeth. And the earlier we identify a problem, the more options we may have for managing it.
That's why we offer FREE dental health checks at Luna.
Our veterinary team can take a look at your dog's teeth and gums, talk through any concerns and help you understand whether further dental care is needed.
We're welcoming dogs at our clinics in Bristol, Reading and Eastleigh, with Surbiton opening soon.
Or, if you can't visit us in person, you can upload photos of your dog's teeth online for an initial review.
Book Your FREE Dental Check at Luna →
And if you're a small-dog parent who's spent years worrying about their dog's teeth, you're certainly not alone.
At Luna, we believe every dog deserves access to quality dental care. That's why we offer transparent, fixed pricing, so you know what to expect before treatment begins.