Molecular characterization of Equine Group A Rotaviruses currently circulating in young foals with diarrhea in Argentina

were analysed with a modified McMaster method only. Horses shedding 200 strongyle epg were treated with an anthelmintic. The owners were instructed to send the sample MS 2 of their horse 42 days after the analysis of the 1st sample to the laboratory and the samples MS 3 and MS 4 after another 90 days, resp. In total,1232 faecal samples from 518 horses (121 farms) were analysed. From 518 horses of which faecal sampleswere sent in asMS1, themean FECwas 167 epg. Thereafter, samples from 308 horses sent to the laboratory as MS 2 revealed a mean FEC of 136 epg. Thereafter, although recommended by the practice, the number of samples and horses, resp. considerably decreased. 184 samples sent in asMS 3 had a mean FEC of 112 epg, whereas the mean FEC of 72 MS 4 – samples dropped to 100 epg. Faecal samples exceeding the strongyle cut-off value of 200 epg were found on 16/121 farms (13.2%). 93 horses (18.0%) exceeded the strongyle cut-off value one time, 37 horses (0.7%) two times and 5 horses (0.1%) three times during the study period. Most horse owners did not send in the faecal samples at the recommended time. The difference in epg between two subsequent samples of untreated horses was compared to the interval in days between the analyses of the same subsequent samples. There was no statistically significant difference in the percentage of samples pairs with a difference < or 200 epg between samples sent in before and after the recommended interval of 42 days and 90 days, resp. The applied faecal sampling scheme has led to a reduced pasture contamination with strongyle eggs. There is no obvious risk for an increase in pasture contamination when extending the interval between the samples for untreated horses. Therefore the interval between the samples can be chosen according to the egg reappearance period of the drug class used for the treatment of the high strongyle egg shedders.