Field studies on endoparasites of Thoroughbred foals on seven farms in central Kentucky in 2004

Abstract

Fecal samples (n=1,584) for a parasite study were collected from Thoroughbred foals (n=349), 28 to 330 days old, on seven farms in central Kentucky during 49 monthly trips from May to October, November, or December 2004. The main purpose was to determine possible drug resistance of ascarids, also of strongyles, to ivermectin (IVM) and other commercially available compounds [fenbendazole, moxidectin (MOX), oxibendazole (OBZ), and pyrantel pamoate]. In addition, interest was on prevalence of foal parasites. Qualitative data were obtained by recording presence or absence of ascarid and strongyle eggs in feces from 7 to 25 days after treatment of some of the foals. None of the compounds completely eliminated ascarid eggs in feces of all foals posttreatment. Activity on ascarids was significantly the highest for OBZ and lowest for IVM. Activity on strongyles was significantly higher for IVM and MOX than for the other compounds. Prevalence (mean percentage of foals infected) was recorded for eggs of Parascaris equorum (39%), of strongyles (32%), and of Strongyloides westeri (2%) and oocysts of Eimeria leuckarti (28%) in feces of foals. One or more foals had infections of P. equorum on six farms (86%), strongyles on seven farms (100%), S. westeri on two farms (29%), and E. leuckarti on six farms (86%). The oldest foal infected with E. leuckarti was 301 days of age. Comparison was made on the prevalence of parasites in foals on five of the same farms in the 2004 study, which were part of a similar 14-farm project in 2003 (Lyons and Tolliver in Parasitol Res (2004) 92:400-404).

Parasite field study in central Kentucky on thoroughbred foals (born in 2004) treated with pyrantel tartrate daily and other parasiticides periodically

“…In the present research, ascarid eggs were passing in feces of three foals after treatment with IVM/PRAZ. This may be similar to recent reports of lower than the initial activity of IVM on ascarids (Boersema et al 2002;Hearn and Peregrine 2003;Lyons et al 2006).…”

“…A qualitative method (designated as a "float") of examination of feces for parasite eggs/oocysts was used entirely for the first few months of the study (Lyons et al 1988(Lyons et al , 2006. A brief description of the method used to process 1 g of feces is as follows: (1) comminute feces using a mortar and pestle, (2) wash material into a sieve and pour liquid passing through into a 15-ml test tube (TT), (3) centrifuge TT, (4) decant TT, (5) add saturated sugar solution (SSS) to TT and stir contents with wooden applicator stick, (6) fill TT with SSS and put on a coverslip, (7) centrifuge TT, (8) place two coverslips (one on TT during centrifugation and a second one added when first one is removed) on a glass slide, (9) examine coverslips with a compound microscope at 100×, and (10) record the presence or absence of eggs of ascarids, strongyles, Strongyloides westeri, and tapeworms, and oocysts of Eimeria leuckarti.…”

“…Resistance of small strongyles was found extensively for the benzimidazoles and pyrantel pamoate (PRT), but not for ivermectin (IVM) and moxidectin (MOX) (Kaplan et al 2004;Lyons et al 2006). There are a few reports of resistance of small strongyles to piperazine; the number of publications is probably low because of current infrequent usage of this compound.…”

“…There are a few reports of resistance of small strongyles to piperazine; the number of publications is probably low because of current infrequent usage of this compound. Recently, there were indications of resistance of ascarids (Parascaris equorum) to IVM and probably MOX (Boersema et al 2002;Hearn and Peregrine 2003;Lyons et al 2006).…”

A field study on the anthelmintic resistance of Parascaris spp. in Arab foals in the Riyadh region, Saudi Arabia

“…However, reduced IVM efficacy against Parascaris spp. has been reported from different parts of the world including North America (Lyons et al 2006;Slocombe et al 2007), Europe (Boersema et al 2002;Lind & Christensson 2009;Veronesi et al 2009;N€ areaho et al 2011;Laugier et al 2012), Brazil (Molento et al 2008), Australia and New Zealand (Armstrong et al 2014;Bishop et al 2014;Beasley et al 2015). Intensive use of MLs such as IVM appears to be associated with development of resistance in Parascaris spp.…”