Comparison of scratching behaviour of growing pigs with sarcoptic mange before and after treatment, employing two distinct approaches.

In a closed pig breeding and finishing herd suffering from sarcoptic mange, two selected groups of pigs were filmed during a period of 10 days before and after treatment. The observation always commenced each hour and lasted for 15 min. Before treatment, observations was done round the clock, after treatment from 8:00 to 22:15. Before treatment the pens were stocked with 11 (pen A) and 10 (pen B) growing pigs (Large WhitexLandrace sows; 5 months old) with an average weight of approximately 70 kg examined for sarcoptic mange by skin scrapings and ELISA. The animals had never been treated with an acaricide or endectocide before. After 10 days, the pigs were treated twice (18 days interval) with Dectomax 1% solution for pigs (Pfizer, Austria) at a dose of 0.3 mg Doramectin i.m./kg body weight. After treatment, seven pigs were observed in both pens. Most scratching actions both before (83.1%) and after (94.5%) treatment were of one to 10 s. After treatment, the 10 s-scratching episodes decreased by 67.3% (from 21.2 to 6.9 mean SRE/pig), and the scratching actions of longer than 10 s by 91.7% (from 4.3 to 0.4 mean SRE/pig), such that the latter could be observed only occasionally after treatment. A distinct increase in scratching activity both before and after treatment could be observed primarily between 10:00 and 15:00. Significant differences of scratching and rubbing activity between before and after treatment could also be seen at midday. The interpretation of the scratching index values before and after the treatment were carried out according to Cargill et al. [Cargill, C., Davies, P., Carmichael, I., Hooke, F., Moore, M., 1994. Treatment of pigs with doramectin to control sarcoptic mange. Proceedings of the 13th IPVS Congress, Bangkok, Thailand, p. 238] with the maximum and minimal limiting values specified in the literature, and compared with calculations using the method described by Hollanders et al. [Hollanders, W., Harbers, A.H.M., Huige, J.C.M., Monster, P., Rambags, P.G.M., Hendrikx, W.M.L., 1995. Control of Sarcoptes scabiei var. suis with ivermectin: influence on scratching behaviour of fattening pigs and occurence of dermatitis at slaughter. Vet. Parasitol. 58, 117-127]. Depending on the methods used and the limiting values set, 6.7-34.6% of the observations before and 2.0-17.3% of the observations after treatment revealed a "strong evidence of mange" or a "suspicion of mange". All other observations indicated that the pigs were free from mange.