A field study on the efficacy of doramectin against strongyles and its egg reappearance period in horses.

The aim of the present study was to determine the efficacy and the so-called "egg reappearance period" (ERP) of doramectin in horses naturally infected with strongyles during a period of 34 weeks. A group of yearlings of 10 animals was treated intramuscularly with doramectin at a dose rate of 0.2 mg/kg bodyweight (BW) at the begin of the grazing season. To obtain comparable data, another group of yearlings (n = 10) was treated orally with ivermectin at a dose rate of 0.2 mg/kg BW. Individual faecal samples were examined for strongyle egg counts per gram of faeces (EPG) in two-week intervals. Twelve weeks later, a second treatment was given in both groups with the respective anthelmintic followed by a third treatment when the group mean egg count reached > or = 200 EPG. The efficacy of doramectin was > or = 96 % and that of ivermectin 100%, based on the mean egg counts two weeks post treatments (wpt). The highest and the lowest extensity of the efficacy (average values) for doramectin were 90% and 41% two and ten wpt, respectively, whereas these values for ivermectin differed from 100% (two wpt) to 24.3% (eight wpt). The ERP was found to be 10 and 8 weeks for doramectin and ivermectin, respectively.

Effect of age, sex and season on the prevalence and intensity of helminth infections in domestic pigeons (Columba livia) from Bursa Province, Turkey.

The one-year study reported in this paper was carried out from April 2002 to March 2003 in domestic pigeons (Columba livia) of Bursa Province (Turkey) to determine the occurrence of helminth species and to evaluate the effect of host age, sex and season on their prevalence and intensity. A total of 100 (31 young and 69 adult) domestic pigeons were necropsied and examined. The results of necropsies revealed that 74 pigeons harboured helminth infections. Three helminth species were identified: Baruscapillaria obsignata (63%), Ascaridia columbae (42%) and Raillietina echinobothrida (1%). There were no significant differences in the prevalence of B. obsignata and A. columbae by host age and sex. Significantly the highest prevalence rate of A. columbae was observed in the autumn months, but there was no significant difference in the seasonal prevalence of B. obsignata. The mean intensity of B. obsignata and A. columbae was higher in adults than in young pigeons but it did not differ significantly between the two sexes. The highest mean intensity rate of B. obsignata was observed in the autumn, while there was no significant difference for A. columbae with regard to season. From the data obtained in this study it can be concluded that in regions with similar climatic conditions as those in the present study area, pigeon breeders should be cautioned especially of B. obsignata and A. columbae infections of adult pigeons in the autumn months.

Benzimidazole resistance in cyathostomin populations on horse farms in western Anatolia, Turkey.

A cross-sectional survey was performed on ten stud farms in western Anatolia, Turkey, in order to provide the first information on the problem of anthelmintic resistance in equine strongyles in this country. Benzimidazole (BZ) resistant cyathostomin populations were detected on seven farms if pre- and post-treatment egg counts are compared in treated animals and the resistance is defined as a mean faecal egg count reduction (FECR) of <95% with a lower 95% confidence limit of <90%. Egg hatch tests using an ED(50) of 0.1 microg/ml thiabendazole as the cut-off value confirmed BZ resistance on four of the seven farms. The probable reasons for the occurrence of BZ resistance are discussed. Resistance to pyrantel embonate or macrocyclic lactones, evaluated on five and six farms, respectively, was not detected using the FECR test.