Source: Alberta Farm Animal Care
Horns of livestock, particularly, cattle, sheep, and goats are sometimes removed for safety and economic reasons (1). Producers routinely remove the horns of beef and dairy cattle to decrease risk of injuries to workers and other animals, and to minimize financial losses from carcass bruising (in beef cattle; 1). The Canadian Beef Quality Audit states that carcass bruising costs the industry $10 million per year (2). Horns are hard, permanent adaptations of the skin that develop from unique skill cells (corium) at the base of the horns (2). Horns begin as buds at the base of the poll and begin to attach to the frontal bone of the skull that overlies the frontal sinus at approximately 2 months of age (2). As horns grow, the frontal sinus attaches to the adjacent portion of the horn and the cornual nerve provides sensation to the horn (2,3).
Disbudding involves destroying the horn-producing cells (corium) of the horn bud before attachment to the skull (2,3). The Code of Practice for the care and handling of beef and dairy cattle require producers to disbud calves as early as practically possible, while in the horn bud stage (~2-3 months of age for beef calves and less than 3 weeks of age for dairy calves; 1,7). As well, the Code of Practice for the care and handling of dairy cattle recommends disbudding over dehorning as it is less invasive (7). For example, disbudding removes the horn buds without opening the frontal sinus, causing less tissue trauma (1,3).
Methods of disbudding include: thermal cautery (electric or butane-powered disbudding iron), chemical paste to cauterize the horn buds (1), or physical removal using knives, scoops, shears, cups, or tubes (3). Hot iron is most commonly performed but is quite painful. Caustic paste (e.g. sodium hydroxide, calcium hydroxide) applied to the horn bud can damage the surrounding skin and/or eyes of calves (3). Thermal cautery may cause less distress than physical disbudding (e.g. scoop) because the sensory receptors that detect pain are destroyed therefore pain perception is reduced (3).
Dehorning involves the removal of horns after they have developed from the horn bud and have attached to the skull (1,3). Once the horns develop, something called the cornual diverticulum of the frontal sinus is present, which makes surgical dehorning more invasive than disbudding; there is more risk of sinusitis, bleeding, and infection (3). The Canadian Veterinary Medical Association (CVMA) supports disbudding/dehorning provided that disbudding is performed at less than one month of age, appropriate anesthesia and peri-operative analgesia are used for pain control, and bleeding is controlled when dehorning (4).
Methods of dehorning include: hot-iron, chemical (e.g. caustic chemicals), physical (guillotine shears, dehorning knives, saws, scoops, cups, high tension rubber bands; 3). All methods of physical dehorning cause pain and side effects (2). Minimizing pain during disbudding and dehorning procedures is important for limiting the altered behaviour and physiologic states of animals such as tail wagging, head movement and rearing (3). A producer’s herd veterinarian is the best resource for possible methods of pain mitigation that can be used during and after disbudding and dehorning (1). Local anesthesia in combination with an analgesic provides the best pain relief (2). Injecting local anesthesia around the cornual nerve desensitizes the area, makes dehorning easier on the calves and handlers, and can relieve pain for several hours (2,3,4). As of January 1, 2016, the Code of Practice for the care and handling of beef cattle requires that pain control be used, in consultation with a veterinarian, when dehorning calves after horn bud attachment (1).
Horned goats can cause serious injuries to handlers and herd-mates (4). Disbudding before 10 days of age has been shown to cause the least stress to goats (4). Heated iron or electrical devices can be used and applied to each horn to deaden horn-growing tissues but must be performed by a competent person using proper techniques (4). As for sheep, dehorning and disbudding is not required as many of the common breeds in Canada are polled (have no horns; 5). Some producers will trim the tips of horned sheep to prevent injury or interference with normal everyday behaviours such as sight, eating and drinking (5). Under certain circumstances, it may be necessary to completely dehorn sheep; if so, a licensed veterinarian must perform this procedure using anesthesia and peri-operative analgesia (5).
A non-invasive welfare friendly alternative to dehorning and disbudding is to select and breed polled cattle, sheep, and goats to dehorn the population of horned animals (2,3). The polled gene is a dominant trait that will appear in all offspring of homozygous polled males (2). It was previously thought that the polled gene was associated with decreased productivity; however, recent research has shown that there is no difference in several traits between horned and polled cattle (2). Despite its complexity, the beef industry is steadily making progress in genetically dehorning cattle via polled breed selection. The Canadian Expert Committee on Farm Animal Welfare and Behavior promotes the use of polled sires in the Canadian beef industry and deems genetic dehorning as the most welfare friendly technique (2). However, widespread introduction and use of polled genetics in the livestock industry will require the involvement of producers, artificial insemination suppliers, researchers, and breed associations (3).
References
- 2013. Code of practice for the care and handling of beef cattle. http://www.nfacc.ca/pdfs/codes/beef_code_of_practice.pdf (Accessed 13 June 2017.)
- Anderson, N. 2009. Dehorning of calves. http://www.omafra.gov.on.ca/english/livestock/dairy/facts/09-003.htm (Accessed 13 June 2017.)
- 2007. Welfare implications of the dehorning and disbudding of cattle.https://www.avma.org/KB/Resources/LiteratureReviews/Documents/dehorning_cattle_bgnd.pdf (Accessed 14 June 2017.)
- 2016. Disbudding and dehorning of cattle – position statement. https://www.canadianveterinarians.net/documents/disbudding-and-dehorning-of-cattle (Accessed 14 June 2017.)
- 2003. Code of practice for the care and handling of goats. http://www.nfacc.ca/pdfs/codes/goat_code_of_practice.pdf (Accessed 13 June 2017.)
- 2013. Code of practice for the care and handling of sheep. https://www.nfacc.ca/pdfs/codes/sheep_code_of_practice.pdf (Accessed 13 June 2017.)
- 2009. Code of practice for the care and handling of dairy cattle. http://www.nfacc.ca/pdfs/codes/dairy_code_of_practice.pdf. (Accessed 13 June 2017.)
