Why Do Pigs Have Curly Tails? Everything You Need To Know About Pig’s Tails

Domestic pigs thought to originate from China have curly tails (1)

Pigs have become one of the most loved animals in recent years. The growing popularity of pig decoration, pet pigs, and pig obsession has many people asking about pigs. 

Some of the common questions include curiosity around why pigs have curly tails if the tail indicates a pig’s emotional health and other similar questions. 

This article will answer those questions. 

Why do pigs have curly tails? Many domestic pig breeds have curly tails because that trait was bred in domestic Chinese pigs over thousands of years. Wild pigs don’t have curly tails, except for a few wild pig breeds in China. It is likely that curly tails was not an intended trait bred by Chinese farmers, but was an accidental trait that was bred from pig fighting. 

Pig breeds that originated out of China have curly tails. It’s believed that any pig breed with at least some ancestors out of China will have a curly tail. In China, pig fighting has been a popular sport for thousands of years. 

China is one of the few countries in the world that still allows pig fighting. During a pig fight, the pigs bite each other’s tails. As a result, pigs with curly tails are more likely to win the fight. Over thousands of years, the winning pigs, aka the survivors, developed curly tails. 

Another theory is that Chinese farmers liked curly tails and purposefully bred curly tails into their pigs. This could have also been because some pigs were then used in pig fights. 

Or, it could be a trait that was developed from wild hogs, a few of which have curly tails in China. 

Many breeds of domestic pigs have curly tails (1)

But, contrary to popular belief, China has wild hogs without curly tails as well. 

The belief that all pig breeds with curly tails originate from China cannot be proved. For example, the Large White Pig originates from Yorkshire England, not China. Chinese pigs could have been used as some of the parent breeds of the Large White Pig, but that would have had to have been thousands of years ago. 

There is no documentation on the breeds used to create the Large White Pig, but it was first recognized in the late 1800s as a breed originating out of the Yorkshire Pig. Once again, the origins of the Yorkshire pigs are not documented but was recognized in the 1700s as a pig breed.

Conversely, the Meishan pig, developed in China has a straight tail. 

Before that, it seems like people really didn’t pay attention to the breeds of pigs or their origins. 

A less likely theory is that a pig’s curly tail was developed to prevent farm pigs from biting each other’s tail. This theory arises from the problem of factory farm pigs, who have a tendency to bite each other. 

Factory pigs usually have their tails docked and their teeth shortened to prevent this issue. However, the issue of pigs biting each other is usually only an issue on factory farms. On the family farm or rural farm, pigs seldom bite each other. 

The stress of many hogs raised in a smaller area brings out the biting tendency. In the past, pigs weren’t confined to the same degree and so probably didn’t have the tendency to bite each other. 

Do all pigs have curly tails?

Not all pig breeds have curly tails. Many breeds of domestic pigs have curly tails, but the majority of wild pigs do not have curly tails. Interestingly, the feral hogs of Texas have straighter tails.
Feral hogs are wild pigs that originate from once domesticated pig breeds. 

Several domestic pig breeds have straight tails. Potbellied pigs, Tamworth, Kunekune, and Mulefoot all have straight tails even though they are domesticated pig breeds. There are other domestic breeds that have straight tails such as the endangered Cinta Senese Pig from Italy. 

A few breeds of domestic pigs have straight tails (1)

  • Potbellied pigs (almost all 12 breeds of potbellied pigs have straight tails)
  • Vietnamese Pig
  • Tamworth Pig
  • Kunekune pig – can have a straight or curly tail
  • Mulefoot pig
  • Cinta Senese Pig
  • Ba Xuyen Pig

What does it mean when a pig’s tail is straight?

Many domestic pig breeds have curly tails. When a pig, who normally has a curly tail, has a straight tail, it can be an indicator of the pig’s mood. One study in the Netherlands found that pigs housed in stressful environments bore a straight tail, while the same pigs housed in less stressful environments had a curly tail. 

Farmers have been saying that for decades. 

Indeed, farmers have long noticed that pigs whose living conditions are filthy or crowded have straight tails. This also happens when pigs have infrequent or unreliable food sources. 

In other words, 

If pigs are stressed out, they are much less likely to have a curly tail. 

Some domestic pigs have straight tails (1)

This has also been demonstrated by individual pigs. Often, a pig that is purchased or adopted from a stressful environment into a calm, cleaner one, will have a curly tail after a few months of the new lifestyle.

For some breeds of pigs, a curly tail that goes straight can mean that the pig has too many worms for its comfort. Most pigs have at least some worms, but when the worms become overwhelming to the pig’s health, it can affect the tail. 

At that point, the tail may straighten.  

Why do wild pigs have straight tails? 

Most wild hogs breeds have straight tails. But, it’s interesting that even domestic pig breeds, with curly tails, have straight tails when they become wild feral colonies. 

In Texas, much of the Southern United States, and parts of Canada, once domesticated pig breeds have become wild feral pigs. Over the last few decades, these feral pigs have grown in great numbers, even to the point of threatening native plants and animal species. 

And those feral breeds have straight tails, even though their ancestors had curly tails. 

Wild Pigs don't have curly tails. This is a brush ear pig, a wild boar (1)
This is a wild pig, called a brush ear pig.

Why? 

One theory revolves around the happiness in pigs that are believed to be shown in the curly tail. If a pig’s curly tail demonstrates contentment in a pig, then a wild pig may have a more stressed-out lifestyle. 

It may also be that a straight tail shows neither happiness or stress, but a neutral attitude. 

Either way, the curliness of a pig’s tail will continue to be studied and theorized about. 

Do pigs tail wag when happy?

Farmers have long believed that pigs will wag their tails when happy, much like a dog. Pigs do often wag their tail. 

But the study in the Netherlands found that pigs can also wag their tail when stressed and when displaying positive social behavior. 

A pig’s tail wagging can be an indicator of a happy pig, an exploring pig, or an upset pig. You can best tell the mood of your pig by watching other indicators of your pig’s mood. 

Not all pigs have curly tails (1)

These indicators include the sounds your pig makes, whether it is active or lethargic and the level of aggression your pig displays. 

Do mini pigs have curly tails?

Mini pigs are not an actual breed of pig. Most mini pigs are either Potbellied pigs or Kunekune pigs. Potbellied pigs do not have curly tails and Kunekune pigs can have either straight or curly tails. 

As a result, most pigs that are marketed as mini pigs do not have curly tails. 

Chart of Pigs Breeds With Straight or Curly Tails And Their Origins

Breed of Pig Curly Tail Straight Tail Origins
Duroc Pig Curly Tail New Jersey 
Large White Pig Curly Tail  England
Berkshire Pig Curly Tail England
Pietrain Pigs  Curly Tail Belgium
Hampshire Pigs  Curly Tail Scotland
Pot Bellied Pigs Straight Tail Vietnam
Guinea Hog Curley Tail – USA USA
Hereford Curly Tail Iowa, USA
Chester White  Curly Tail Pennsylvania, USA
Danish Landrace Pig Curly Tail Denmark
Tamworth Pigs Straight Tail Ireland
Gloucester Old Spots Curly Tail  England
Vietnamese Pig Straight Tail Vietnam
Mangalica Pig Straight Tail Hungary
Meishan Pig China
Kunekune Curly or Straight Curly or Straight New Zealand
Essex Curly Tail  England
Mulefoot Pig Straight Tail  USA
Cinta Senese Straight Tail  Italy
Ba Xuyen Pig  Straight Tail South Vietnam

Related Articles

These other articles about pigs may be useful to you as well.

How To Care For Your Pet Pig, Everything You Need To Know

Do Pigs Have Sweat Glands And Other Interesting Facts

Why Can’t Pigs Look Up At The Sky? (And Other Interesting Facts)

Additional Resources

https://stud.epsilon.slu.se/4692/7/groffen_j_120820.pdf

Annemaria Duran

Hi, I’m Annemaria Duran. I moved out to the country 6 years ago, mainly so I could have more land. I love all aspects of country living. First, we got chickens, then ducks. Now we have sheep, goats, and rabbits. I'm always learning and love sharing it!

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