Even though there is a major shift in the north Australian beef industry towards breeding of polled cattle and disbudding when young, dehorning by amputation, which may result in frontal sinus exposure, will continue to occur. This project tested whether patching of the wound immediately after dehorning by application of a dry 7.5 cm square cotton gauze surgical swab enhances healing. A patch was anticipated to enable more rapid clotting and would form the matrix for a large scab which would cover and protect the sinus. The scab would slough as the wound heals and because swabs are made of pure cotton, they are fully degradable in the environment. Fifty tropically-adapted heifers weighing 180-200 kg on a Northern Territory station were selected for the experiment. Five weeks after surgery, the heifers were transferred to a feedlot in south-east Queensland where observations continued for a further 8 weeks. Observations were twice daily for 2 weeks and then each 7-16 days (average 10-daily) to the end of the experiment.
Final report summary: Gauze swabs (7.5 cm square patches) were placed on the dehorning wounds in 24 of 50 tropically-adapted heifers weighing 180-200 kg. Frontal sinus exposure averaged 3.5 cm in diameter. Application of swabs reduced haemorrhage (P<0.01). Half the patches were dislodged within a day of surgery, and 80% of these within an hour. The remainder sloughed 10-44 days after surgery. Patches sealed exposed frontal sinuses from the time of application if they were not dislodged. Sealing took up to 4 weeks in 96% of un-patched wounds. Patches reduced purulent exudation from 11% to 1% of wounds (P<0.01), ie, it substantially reduced secondary bacterial infection. No fly strike occurred in patched wounds. There was a non-significant trend for patched wounds to reach the post-scab healing phase (6-13 weeks after surgery) earlier than un-patched wounds. The incidence of behaviours indicating pain was high in the 2-3 days after surgery and abated over 2 weeks. Behavioural data indicated that dehorned calves should be segregated from other cattle after surgery and that pasture feeding is recommended over hand feeding in this period. Patches had no impact on pain. Use of patches is recommended, though a cost-effective method to increase adherence will improve their efficacy.