Both male and female cattle can possess horns, contrary to the common confusion that only bulls have them. Horn presence is determined by the animal’s breed and genetic makeup, not its sex. Horns are permanent structures composed of a bony core covered by a keratin sheath, and they grow continuously throughout the animal’s life. Whether a cow, a bull, or a steer (castrated male) has horns depends entirely on the genes inherited from its parents.
The Biological Answer: Horns, Sex, and Genetics
The presence or absence of horns in cattle is controlled by a single gene pair, where the trait for being naturally hornless, known as “polled,” is genetically dominant. This means that an animal only needs to inherit one copy of the polled gene from either parent to be hornless. Conversely, an animal will only develop horns if it inherits two copies of the recessive horned gene, one from each parent.
This genetic mechanism allows breeders to select for the polled trait, making it a common feature in many popular breeds. The gene for horns is carried equally by both sexes. A separate, sex-influenced genetic condition results in “scurs,” which are small, loose, and incompletely developed horn-like growths attached only to the skin. Scurs are distinct from true horns and are more frequently expressed in males that are genetically polled.
Differences in Horn Structure Between Sexes
When horns are present in both sexes of a breed, their physical structure is notably affected by sex hormones. Bulls, which possess higher levels of testosterone, tend to develop horns that are thicker and more robust at the base. This thickness provides structural integrity for the aggressive head-to-head fighting bulls engage in to establish dominance within the herd. Their horns are shorter and stouter, built for impact and leverage.
In contrast, the horns of a cow tend to be thinner and often longer in proportion to their body size. While a cow’s horns may be used defensively, they do not require the structural reinforcement needed for ritualized combat. The shape and curvature are also influenced by the breed; some cows have a more graceful, sweeping curve, while bulls in the same breed display a heavier, more forward-thrusting set of horns.
Why Many Cattle Lack Horns
The primary reason most people see cattle without horns is due to widespread human intervention driven by safety and economic considerations. One major factor is selective breeding, where producers consistently choose to breed naturally polled animals to eliminate the horned trait from their herds. Since the polled gene is dominant, it is a straightforward process to breed for hornlessness, which avoids the need for physical horn removal.
In operations using horned breeds, the physical removal of horn buds, known as “disbudding” (on young calves) or “dehorning” (on older cattle), is a standard management practice. This procedure is implemented primarily for the safety of the animals and human handlers. Horned cattle can injure each other, leading to health issues and financial losses. Hornless cattle are also easier and safer to handle, transport, and manage in close quarters, improving herd welfare and farm efficiency.