Dehorning, or disbudding, is the process of removing or stopping the growth of the horns of livestock. Cattle, sheep, and goats are often dehorned for economic and safety reasons. Horns can pose a risk to humans, other animals and to the bearers of the horns themselves (horns are sometimes caught in fences or prevent feeding). The procedure is commonly performed early in an animal's life, along with other actions such as docking (tail amputation) and castration. Dehorning is considered by some concerned with animal welfare to be cruelty because of the pain it can cause. Many breeds of cattle and sheep are naturally polled (hornless) and therefore do not need to be dehorned. Most other livestock species cannot easily be bred to lack horns naturally – for example, the poll gene in goats is closely linked to hermaphrodism.
- Horns may cause injuries to handlers or other cattle.
- Horned livestock take up more space.
- Horned livestock may require specialist equipment, such as feeders and cattle crushes.
- In some breeds and in some individuals, horns may grow towards the head, eventually causing injury.
- Horns may become broken, causing blood-loss and potential for infection.
- Horned livestock may become trapped in fences or vegetation.
- Horned livestock are better able to defend themselves and their young from predators such as wolves and dogs.
- Horns provide a secure point for roping or holding the animal's head.
- Horns are traditional in some breeds, and breed standards may require their presence (for example, Texas Longhorn, Highland and White Park cattle).
- In some areas horns are of cultural significance, often being decorated or even trained into strange shapes.
- Some types of yokes used by draught oxen require the presence of horns.
- Dehorning takes time and costs money.
- Horns are needed by the animal for thermoregulation and cooling.
- Dehorning is extremely painful to the animal
Dehorning is normally performed with local anesthesia and sedation by a veterinarian or a trained professional. To minimize discomfort and risk, dehorning is being increasingly performed when horns are small "buds", the process to be called "debudding" or "disbudding." Removal of larger horns is usually performed during spring and autumn to avoid fly season. In very large horns, "tipping" (removal of the tip of the horn) may be recommended to minimize bleeding. 
Cauterization is the process of killing the growth ring of the horn using heat. This process is done when the animal is very young, no more than three or four weeks old—that way the horns are not very big and have not had time to grow attached to the skull. The earlier in the calf's life cauterization is done, the less pain and stress is inflicted on the calf. Cauterization is usually done with a dehorning hot iron after the area is numbed with local anesthesia.
A curved knife can be used to cut the horn off when the calf is younger than a couple of months old. It is a simple procedure where the horn and the growth ring is cut off to remove the horn.
For older calves, usually under eight months of age, the horns are starting to grow attached to the skull, so a cup dehorner or a Gigli saw, a type of surgical cutting wire, is used. There are several different types of cup dehorners, but they all serve the same function of removing the horn and growth ring. Since the horn is tougher it takes more force to remove it so tools that provide some leverage are need. Gigli saw wire is used on horns of older calf’s horns that have grown too large for the cup dehorners.
The most recent development in dehorning technology is the dehorning (caustic) paste. The paste is used on calves at less than two days old. The hair around the horn is trimmed back and then the paste is spread all over the horn bud and around the base of the horn on the growth cells. The paste kills the growth ring of the horn and then the horn falls off like a scab when it is healed. However, this method bears a risk of the paste causing injury to the animal's eyes or other tissues if used during periods of rain. That is why it is used carefully on animals housed indoors.
For mature cows that were not dehorned when they were young, it is common practice to just cut off the pointed end of the horn. This practice is called horn tipping; it is less stressful on the cows because there is no blood loss and the horn is cut off where there is no longer any nerve endings. This practice does not eliminate the bruising damage done by the horns when cows fight, but it does eliminate the risk of puncture wounds and eye loss from pointed horns. If adult cattle are dehorned, veterinarians recommend it be done using local anaesthetic (Cornual Nerve block).
Today, agricultural professionals and veterinarians recommend dehorning be done before 2 days of age using caustic paste, or using local anaesthetic (Cornual Nerve block) when performing any of the other procedures. Sedation may be recommended, especially for larger animals that require increased restraint. Use of longer-term pain medicine, like NSAIDs, are being researched in the US to ensure food safety.
In 2007, the U.S. Department of Agriculture's (USDA) National Animal Health Monitoring System (NAHMS) survey suggested that most cattle in the U.S. were dehorned without the use of anesthesia at that time. The survey showed that more than nine out of ten dairy farms practice dehorning, but fewer than 20 percent of dairy operations that dehorned cattle used analgesics or anesthesia during the process. While animal rights groups, like the Humane Society of the U.S., condemn dehorning practices, ending the practice would mean increased horn-related injuries to cattle and humans. Polled (hornless) genetics is becoming increasingly popular among dairy farmers, with more polled calves being born every year. As genetic testing becomes more available to the every day farmer, there is increasing potential to remove or at least minimize horned genetics from the dairy gene pool in the future. 
The animal to be dehorned is usually restrained, either using a dehorning table or with chemical restraint (see sedation). This ensures that the dehorning procedure can be done safely and properly. Young calves are run through a head gate (similar to a Cattle crush) or haltered to ensure the safety of the calves and handlers. Calves more than a few months old are held in a head gate and their head restrained with a dehorning table or chin bar. Smaller animals like sheep and goats may be restrained by hand or with use of halters.
- Debeaking or beak-trimming
- Overview of discretionary invasive procedures on animals
- Polled livestock
- "RCVS List of Mutilatory Procedures". Retrieved 9 December 2011.
- "Pain in animals". Retrieved 3 October 2012.
- Hemsworth, P.H., Barnett, J.L., Beveridge, L. and Matthews, L.R. (1995). The welfare of extensively managed dairy cattle - a review. Applied Animal Behaviour Science, 42: 161-182.
- "Peta video on dairy dehorning". Peta. Retrieved 17 October 2012.
- "Dehorning Calves". University of Tennessee Agricultural Extension. 2004. Retrieved 17 December 2013.
- Beattie, William A. (1990). Beef Cattle Breeding & Management. Popular Books, Frenchs Forest. ISBN 0-7301-0040-5.
- "USDA NAHMS Dairy 2007". USDA NAHMS Online. January 2010.  (accessed 17 December 2013).
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