| The aim of this work was to evaluate the efficacy of monepantel to control gastrointestinal nematodes (GIN) of sheep. A faecal egg count reduction test (FECRT) was conducted at the Experimental Stations of INIA, Glencoe Tacuarembó (Farm 1) and Sheep Unit La Estanzuela (Farm 2), Colonia, Uruguay. Following the WAAVP guidelines, on Farm 1, the FECRT was performed using 6-8 month old Merino Dohne or Corriedale male lambs, naturally infected with GIN. On day 0 (May 20th, 2014), three groups of 15 lambs each were selected, blocked by fecal egg count level (FEC) and randomly assigned to one of the following groups: G0 untreated control, G1 treated with monepantel (Zolvix®, Novartis Animal Health Inc.) available at the Animal Health Lab of INIA for FECRT and G2 treated with monepantel new bottle provided by the supplier, both at the recommended dose of 2.5mg/kg B.W. Fecal samples were collected directly from the rectum from lambs, identified with ear tag. On day 9 post-treatment (May 29th, 2014) a second fecal sample was analyzed. On Farm 2, the FECRT was conducted on a group of 8 month old male lambs Milchschaff x Finnsheep to evaluate five drugs, but here we will describe only monepantel evaluation. For this purpose, 10 lambs were remaining as untreated control (G0) and 10 lambs were randomly allocated to be treated with monepantel (G1). Everything was performed as previously described for Farm 1. The percentage of FECR was estimated using the Dash formula and 95% confidence intervals using the BootStreat program. Results for Farm 1, demonstrated a lack of monepantel efficacy. The FECR for G1 was 0.0% (95% CI=0.0 – 49.0) and 40.0% (95% CI=0.0 – 42.0) for G2. For Farm 2, the FECR was 82.1% (95% CI=36.0 – 99.0). Coprocultures demonstrated that Haemonchus contortus was the genus involved in the resistance. |
