All Ears New Study Reveals What Really Determines Ear Length in Dogs

Dog ears come in an astonishing range of shapes and sizes, from the tall, upright ears of a German shepherd to the famously long, floppy ears of a basset hound. For dog lovers, those droopy ears can trigger an almost irresistible urge to gently tug or wiggle them. Now, a new scientific study has gone beyond the cuteness factor and uncovered the genetic reason why some dogs have longer ears than others.

Researchers at the University of Georgia (UGA) have identified the specific genetic variations that influence ear length in dogs, shedding light on a physical trait that has long fascinated breeders, veterinarians, and pet owners alike. The findings were published in the journal Scientific Reports and mark the first time scientists have pinpointed the genetic basis for ear size in dogs, rather than just ear shape or position.

A Large-Scale Genetic Investigation

To uncover the genetic roots of ear length, the research team analyzed DNA from more than 3,000 animals, including domestic dogs, wolves, and coyotes. By comparing genetic information across such a large and diverse group, the scientists were able to narrow down which regions of the genome consistently correlated with ear length differences.

Importantly, the researchers focused their analysis on drop-eared dogs only, meaning dogs whose ears naturally hang down rather than stand upright. This approach allowed them to isolate the genes responsible for how long the ears are, without interference from genes that determine whether ears are upright or floppy in the first place.

What they discovered came as a surprise.

The Unexpected Role of the MSRB3 Gene

The study found that genomic differences near a gene called MSRB3 play a key role in determining ear length. This finding was unexpected because MSRB3 was already known to influence whether a dog has prick ears or drop ears, not how long those ears grow.

MSRB3 is not new to science. In humans, mutations in this gene are associated with hearing loss, which immediately made the discovery more intriguing. Despite studying only floppy-eared dogs, the researchers still found meaningful variation near MSRB3, indicating that multiple genetic layers influence ear traits.

The study revealed that a combination of alleles—different versions of DNA sequences—first determines whether a dog’s ears are upright or droopy. On top of that, an additional allele influences whether those droopy ears are short or long. This explains why two dogs can both have floppy ears yet look dramatically different, like a cocker spaniel compared to a bloodhound.

Why This Discovery Matters

While ear length might seem like a purely cosmetic trait, it has deeper implications. Understanding which genes influence physical features helps scientists map other genetic traits, including those related to disease.

The UGA research team typically studies inherited diseases in dogs, not appearance. However, identifying genes that breeders select for—often unintentionally—can help researchers avoid confusing cosmetic traits with disease-related genetic signals in future studies.

When breeders select dogs for specific looks, such as longer ears, they may also be increasing the frequency of nearby genetic variants that could affect health. Knowing exactly where these genes are located allows scientists to account for them during genetic research and develop better tools to protect canine health.

Selective Breeding and Its Lasting Impact

Many ear shapes seen in modern dog breeds are the result of selective breeding by humans, rather than natural evolution alone. Over generations, breeders have favored certain appearances, amplifying traits that once varied only slightly in wild canids.

Dog ears can be broadly categorized into types such as prick, drop, button, rose, and bat ears. Each type once served a functional purpose. Upright ears helped dogs detect distant sounds, while long, droopy ears aided scent-focused breeds by channeling smells toward the nose and dampening external noise.

Today, some ear shapes are more about appearance than function. A French bulldog’s bat-like ears, for example, are now primarily a defining visual feature rather than a survival advantage. This study highlights how human preferences have shaped canine genetics in precise and measurable ways.

Ear Length and Dog Health

Understanding ear length also has practical health implications. Dogs with long, floppy ears are more prone to ear infections, as reduced airflow can create warm, moist environments where bacteria and yeast thrive. While the study did not directly address health outcomes, identifying the genetic basis of ear length could eventually help veterinarians understand why certain breeds face higher risks.

In the future, breeders may be able to use genetic testing to make informed decisions that balance appearance with health. By reducing the frequency of harmful alleles while preserving breed standards, it may be possible to improve overall canine well-being.

Why Dogs Have Such Diverse Ears

Dogs are one of the most genetically diverse mammals on Earth. From the smallest Chihuahua to the largest Great Dane, selective breeding has pushed natural variation to extremes. Ear length is just one example of how small genetic changes can lead to dramatic physical differences.

Studies like this one also provide insights into broader biological questions. Similar genetic regions linked to ear size have been identified in other mammals, suggesting that the mechanisms behind ear development may be shared across species.

What This Means for Future Research

Now that researchers have identified the precise genomic region associated with ear length, future studies can factor this knowledge into disease mapping. This reduces the risk of misinterpreting cosmetic traits as disease-related genetic signals.

Ultimately, the goal is to use genetic knowledge not just to explain why dogs look the way they do, but to reduce inherited diseases and improve quality of life. By understanding which genes are being selected—intentionally or not—scientists and breeders can work together to make healthier choices for future generations of dogs.

A Small Feature With Big Scientific Value

What started as curiosity about floppy dog ears has turned into a meaningful scientific breakthrough. The study shows that even traits we consider purely aesthetic are shaped by complex genetic systems with real biological consequences.

So the next time you see a dog with impressively long ears, you’ll know there’s a specific genetic story behind them—one that connects appearance, evolution, health, and human influence in a surprisingly elegant way.

Research paper:
https://www.nature.com/articles/s41598-025-33036-0