The effects of using antisepsis on the healing of dehorning wounds in cattle
Dehorning of cattle is a common procedure worldwide, and it has been reported that it is often carried out without any antiseptic preparation of the skin around - the horn prior to the operation. The aseptic technique is not considered practical or even necessary for many operative procedures performed on cattle (Heinze, 1970). The aseptic technique is, however, known to play an important role in the healing of wounds in general and no~ observing i~ results in the invasion of tissues by pathogenic bacteria which delay or prevent healing. The skin is also known to be a common source of contamination of wounds in animals. This project was ~herefore designed to investigate the effects of antiseptic preparation of the skin around the bovine horn on the rates of infection and healing of dehorning wounds. A comparison was also made between cosmetic dehorning, where the horn wound is sutured, with the standard method where the dehorning wound heals as an open wound. Sixty horns of thirty cattle of mixed breeds and over one year of age were dehorned. Two groups of five cattle each were dehorned with no antiseptic preparation of the skin around the horn prior to the operation. One group was then housed in stalls in a building while the other was maintained on a farm under field conditions. Two other groups of five cattle each were dehorned following complete antisepsis which included shaving the hair around the horns using a scalpel blade, washing the area with soap and water and applying surgical spirit. One group farm was then housed in stalls and the other on a under field conditions. A fifth group of five cattle had partial antisepsis done prior to dehorning which involved trimming short the hair around ~he horns using scissors and washing the area with soap and water. This group was kept on a farm where healing took place. The las~ group of five ca~tle had cosmetic dehorning performed, and complete antiseptic preparation of the skin around the horns was done prior to the dehorning. These animals were housed in stalls after the dehorning and the healing of the wounds was observed. In all the dehorning operations the surgeon ensured his hands as well as the equipment used were clean ~o minimise the contamination from these sources. The following parameters were studied: the time taken for the antiseptic preparation and dehorning, which was measured using a stop watch; the types of microorganisms on the skin around the horn and the difference in this microbial population after antiseptic preparation; the incidence of infection of the .horn wounds (Sinusitis) and the microorganisms causing it. Samples for microbiological culture and identification were taken using a sterilised swab culturette, streaked on a blood agar plate and incubated at 370 C for 24 hours. Rectal temperatures and blood leucocyte levels were also assessed every week to determine whether the infection of the horn wounds was spreading to affect the rest of the animal's body. The healing rate was determined by measuring the wound size each week following dehorning using Calipers. The healing time as well as the appearance of. the horn wounds on healing were also studied. More time was spent in observing complete antisepsis than partial antisepsis and no antisepsis in that order. Complete antiseptic preparation more effectively reduced the microbial flora on the skin around the horn as compared to partial antisepsis. The incidence of sinusitis was however similar for all the animals dehorned in the standard way irrespective of the method of antiseptic preparation or the place where the animals were housed during healing. The microorganisms isolated most commonly in sinusitis vulgaris, in order of prevalence Pseudomonas aeruginosa included Proteus and Escherichia coli, which are common faecal contaminants of the environment of the animals. The rectal temperatures occasionally rose above the physiological limit in the animals with sinusitis, but soon re~urned to the normal range. The blood leukocyte levels did not vary significantly from the normal physiological limits in all the animals, with or without sinusitis. Sinusitis, when it occurred, did not delay or prevent healing unless it was prolonged and epithelial cell migration had reached ~he frontal sinus opening. The dehorning wounds where comple~e antisepsis was observed had a shorter healing ~ime ~han the ones where partial or no antisepsis was observed. The wounds where partial antisepsis was observed in turn healed faster than those where no an~isepsis was observed. Cosmetic dehorning took a longer time to perform than the standard method of dehorning but all the animals healed withou~ developing sinusitis. These animals also healed faster as compared to the standard method (without suturing the skin wound). In the standard method, incomplete wound contraction was observed resulting in a large epi~helial scar and an irregular skin margin which was unattractive in appearance. In cosmetic dehorning, however, the skin edges fused well with little scar formation with an attractive postoperative appearance. Antiseptic preparation, and more specifically shaving or trimming the hair around the horns prior to dehorning, were found to enhance the healing of the horn wounds. The application of antiseptics did not reduce the rate of infection of the horn wounds, or sinusitis, and this was most probably due to contamination from the environment. The sinusitis, when it occurred, did not spreaa to affect the general health of the animal. Cosmetic dehorning was more expensive and time consuming than dehorning without suturing the skin wound, but it had the shorter healing time, least infection rate and a more attractive postoperative appearance.