ABSTRACT
Macrocyclic lactones are the most widely used drugs for the control of gastrointestinal nematodes of horses in Argentina. Ivermectin and moxidectin are used as broad spectrum anthelmintics and although there are several international reports on the resistance of Parascaris spp., the resistance status of the local nematode population is largely unknow. This report informs a case of suboptimal efficacy to both drugs to control Parascaris spp in foals in central Argentina. In February 2018, routine fecal parasite egg counts showed a moderate-high number of Parascaris spp eggs (mean = 680 eggs per gram of feces) in foals treated approximately one month before with moxidectin. Upon suspicion of resistance of this parasite to the macrocyclic lactones, 24 of these animals were selected for a fecal egg count reduction test (FECRT). Twelve foals were treated with ivermectin and the remaining 12 animals with moxidectin. Two weeks after treatment, the FECRT was 48.1% and 34.8% for moxidectin and ivermectin respectively (25% of the animals increased the number of eggs in feces after treatment). Five days later, the administration of fenbendazole resulted in a FECRT = 100%. The monitoring of the status of susceptibility or resistance in each establishment is critical for the design of control programs based on rational and sustainable use of anthelmintics.
Subject(s)
Antinematodal Agents/therapeutic use , Ascaridida Infections/veterinary , Ascaridoidea/drug effects , Horse Diseases/drug therapy , Ivermectin/therapeutic use , Macrolides/therapeutic use , Animals , Argentina , Ascaridida Infections/drug therapy , Ascaridida Infections/parasitology , Female , Horse Diseases/parasitology , Horses , MaleABSTRACT
La placenta es un órgano imprescindible para llevar adelante la gestación en mamíferos domésticos. Está constituida por tejidos maternos y fetales y cumple numerosas funciones: intercambio de gases, nutrientes y excreción de productos de desecho, función inmune a nivel de tolerancia y transferencia, función endócrina sintetizando hormonas y factores de crecimiento. Existe una gran diversidad estructural en las placentas de diferentes especies animales. Las clasificaciones de mayor relevancia son la que dependen de la descripción morfológica macroscópica, basada en la distribución de las vellosidades placentarias en el corion del feto y la clasificación histológica, fundamentada en el número de capas que se interponen entre la sangre materna y la fetal, determinando la transferencia de inmunoglobulinas (Igs) a través de este órgano. El objetivo del presente trabajo es describir la estructura placentaria en diferentes especies y su impacto en la transferencia de la inmunidad materno-fetal. (AU)
The placenta is an essential organ for pregnancy in domestic mammals. It is constituted by maternal fetal tissues and fulfills numerous functions: exchange of gases, nutrients and excretion of waste products, prevents the immune system from identifying the embryo as a foreign body and synthesizes hormones and growth factors. There is great structural diversity in placentas of different animal species, and those can be classified in different ways. The most relevant is the macroscopic morphological classification, which is based on the distribution of the placental villi in the corium of the fetus, and the histological, that relies on the number of layers between maternal and fetal blood, determining if there is immunoglobulin (Ig) transfer or it is carried out through the colostrum. The objective of the work is to describe the placental structure in different species and its impact on the transfer of maternal-fetal immunity. (AU)
