Does your dog have “shark teeth”? Veterinarians say that 7% of dogs have an extra row of squeaks

• Veterinarians warn dog owners about “shark teeth” – an extra row of teeth
• Read more: Vets issue urgent warning to owners after rise in number of dogs infected with the disease

Dog owners have been urged to look out for a little-known dental condition that affects seven per cent of canines.

“Shark teeth” — formally known as persistent deciduous teeth (PDT) — are a disorder in which two sets of squeaks emerge from a row of gums.

This occurs when a dog's baby teeth remain fixed in the jaw instead of falling out when adult teeth emerge.

According to veterinarians in a new study, the dog breed most likely to suffer from PDT is the Yorkshire Terrier, followed by the Toy Poodle, Maltese, and Chihuahua.

PDT can cause an irregular bite ('malocclusion'), which may cause mouth bleeding, as well as increase the risk of gum disease, which is a serious infection of the gums.

The new study was led by Corinne Wallis, a research scientist at the Waltham Institute of Pet Science in Leicestershire.

“Dogs use their teeth for many tasks, and as such, it is important for their health and well-being to maintain a healthy mouth,” Wallis and colleagues say.

“Persistent deciduous teeth (PDT), those that do not fall out in time, are associated with malocclusion (misaligned bite), soft tissue trauma and increased risk of gum disease.”

To conduct the study, the team examined the medical records of 2.8 million dogs in the United States over a five-year period, from January 2010 to December 2014.

The dogs were divided into groups based on their weight, ranging from very small breeds (weighing less than 6.5 kg) to very large breeds (over 40 kg).

Overall, among all weight groups, the prevalence of PDT based on the dogs' medical records was seven percent.

In terms of individual breeds, Yorkshire terriers had the highest prevalence of PDT (25.1 per cent), followed by Maltese terriers and poodles (both 14.8 per cent).

Meanwhile, the Greyhound had the lowest prevalence, at 0.1 per cent, followed by the Rhodesian Redbuck (0.2 per cent).

The Great Dane, English Bulldog, and Boxer also showed a low prevalence of the condition (all at 0.4 percent).

In general, the prevalence of PDT was found to be generally higher as the strain size decreased.

Overall, 15% of very young dogs had PDT, while less than 1% of all dogs in all categories >15 kg had the condition.

It is not clear exactly why small breeds are more susceptible to PDT, but it may have a genetic basis.

Like humans, dogs have two sets of teeth in their lives – 28 baby (baby) teeth and 42 permanent (adult) teeth.

A dog's baby teeth begin to appear at three to six weeks of age and generally fall out at six months of age.

At approximately three to five months of age, permanent teeth begin to appear.

When permanent teeth follow the path of normal eruption, they put pressure on the top of the baby teeth.

“However, incorrect eruption trajectory of the permanent posterior tooth or its complete absence can disrupt the resorption process and lead to PDT,” say the authors.

Shark teeth were also 11% more common in overweight dogs, although researchers are not sure why this is.

The team wants owners of very small and small breeds to be aware of the importance of regular veterinary examinations which include an oral examination.

They say it's especially important for young breeds to perform a thorough oral examination at around six months of age to identify and remove any PDT.

“Once identified, PDT can be removed, and if this is performed at six months of age, the chances of problems associated with PDT, such as the development of gum disease or malocclusion, are likely to be greatly reduced,” they wrote.

The new study was published in the journal Research in veterinary science.