Do Cow Horns Continuously Grow? What You Need to Know

Hornless cows have become a common sight today, a reality that could lead many of us to think that cows or bulls do not grow horns naturally. However, this is an erroneous assumption—cows grow horns unless they are bred as polled, dehorned, or disbudded as calves. This raises another key question: Do cow horns grow continuously?

The horns grow continuously throughout the cow’s life. This happens because cow horns are permanent, not seasonal. In addition, the hollow bone that makes up the core of the horn is the only bone in cows that grows perpetually.

It’s important to understand how cow horns grow to fathom why they grow continuously. I’ll discuss both issues in this article, as well as address the question of whether cow horns can grow back when broken or cut off. First, though, let’s have a quick definition of horns.

What Are Horns?

Horns are the hard growths that appear in pairs on the heads of cattle. They have a bone texture at the core and are covered with keratin on the outside. Keratin is the fibrous protein that’s also the primary material making up hooves, nails, hair, feathers, claws, and the external layer of the skin in vertebrates.

Different from antlers in, for example, wildlife, horns have a continuous shape and are not branched. In cattle, horns can vary in shape and size depending on breed and sex. Bulls tend to have longer and larger horns, and breeds like the Longhorn cows have longer horns than the commonly known dairy breeds.

While horns are sometimes linked with digestion, body temperature regulation, and breathing, their primary function in cows is defence against predators. That’s because cows are prey animals and had only their horns to protect themselves, their calves, and other cattle in their herd before they were domesticated.

Do Cow Horns Grow Continuously?

Yes, they do. The hollow bone of the horn is the only bone that grows during a cow’s entire life, meaning that the horns grow continuously.

Unlike animals that have antlers and shed them seasonally, cows never shed the horn bone and sheath. Their horns never stop growing even though horn growth slows down as the cows get older.

For example, Texas Longhorn cows grow their horns their entire life, but they gain most of their horn length by the time they are six or seven years old. After that, horn growth significantly slows down. I’ve explained how long it takes for cow horns to grow in another article.

What Length Do Cow Horns Reach?

There’s no standard length for cow horns—it depends on the breed and the family line. In general, dairy breeds have relatively shorter horns than beef breeds.

Cow horn size can be measured in different ways.

• Tip to tip. Place the end of the measuring tape on the tip of one horn and extend it to the tip of the other horn.
• Total horn. The total length of each horn.
• Base circumference. The length at the base of each horn.
• Composite size. The sum of tip-to-tip length, the total for both horns, and the base circumference of both horns.

A study at Kansas State University that measured horn growth among Brahman and Longman heifers during a feedlot period of 194 days recorded notable differences in horn growth:

Cow horn length can also be affected by wear or damage. Sometimes, damage to a cow’s horn leads to its irreversible loss.

Do Cow Horns Grow Back?

No, they don’t. If damage leads to partial or complete horn breakage, the cow remains that way for the rest of its life. 

Cow horns grow continuously because of skin tissue at the horn bud. In most cases, horn damage or breakage destroys the horn bud tissue, just as dehorning does. Without the corium (the growth tissue), cow horns cannot grow afresh once damaged.

If a cow’s horn is even partially destroyed, this impacts the nerve and blood vessels. This is especially true when the damage affects the hollow bone of the horn (the one connected to the sinuses and growing continuously).