In early studies, the zinc sulfate centrifugal flotation technique was used to detect hookworm and whipworm eggs in humans. There have been variations of this technique over time.1 The centrifugal flotation technique has been used for in vitro studies,2 for recovering Cryptosporidium oocysts from foals,3 and for recovering ascarid and other helminth eggs from soil.4
A detailed description of the McMaster technique for counting equine strongyle eggs was provided by Herd.5 Comparisons of the 2 techniques favor centrifugal flotation for recovery of eggs from various hosts.6 In studies7,8 on recovery of Parascaris equorum eggs and pyrantel tartrate efficacy, the McMaster technique was used initially and findings were confirmed by use of centrifugal flotation.
The McMaster technique has been used in combination with larval cultures for detecting development of anthelmintic resistance on Danish horse farms.9,10 The centrifugal flotation technique, supported by larval cultures that were made from the feces of individual horses, has been used for strongyle group identifications and to measure response to long-term administration of anthelmintics.11–13 Because the apparent increased development of specific anthelmintic resistance is becoming widespread,9–11 a combination of techniques may be necessary for efficacious diagnosis of herd or individual infection. Therefore, the purpose of the study reported here was to compare the McMaster and centrifugal flotation techniques for recovery of cyathostomin eggs from the feces of horses, with diagnostic support by use of larval cultures.
Eggs per gram
Larvae per gram
PARACOUNT-EPG, Chalex Corp, Wallowa, Ore.
Terra-Lite, WR Grace & Co, Cambridge, Mass.
Strongid C, Pfizer Animal Health, New York, NY.
Zimecterin, Merial Ltd, Duluth, Ga.
Zimecterin Gold, Merial Ltd, Duluth, Ga.
Equimax, Pfizer Animal Health, New York, NY.
Belding DL. Chapter 51: the examination of helminths. In: Textbook of clinical parasitology. New York: Appleton-Century-Crofts, 1952;975–980.
Bello TR, Gordon VL. Rapid concentration of strongyle eggs from equine feces for in vitro studies. Am J Vet Res 1970;31:2285–2288.
Kazacos KR. Improved method for recovering ascarid and other helminth eggs from soil associated with epizootics and during survey studies. Am J Vet Res 1983;44:896–900.
Alcaino HA, Baker NF. Comparison of two flotation methods for detection of parasite eggs in feces. J Am Vet Med Assoc 1974;164:620–622.
Craig TM, Diamond PL, Ferwerda NS, et al.Evidence of ivermectin resistance of Parascaris equorum on a Texas horse farm. J Equine Vet Sci 2007;27:67–71.
Slocombe JOD, Lake MC. Efficacy of daily pyrantel tartrate (Strongid C) against strongyles in ponies on pasture. J Equine Vet Sci 2007;27:67–70.
Craven J, Bjorn H, Henriksen SA, et al.Survey of anthelmintic resistance on Danish horse farms, using 5 different methods of calculating faecal egg count reduction. Equine Vet J 1998;30:289–293.
Craven J, Bjorn H, Barnes EH, et al.A comparison of in vitro tests and a faecal egg count reduction test in detecting resistance in horse strongyles. Vet Parasitol 1999;85:49–59.
Tarigo-Martinie JL, Wyatt AR, Kaplan RM. Prevalence and clinical implications of anthelmintic resistance in cyathostomes of horses. J Am Vet Med Assoc 2001;218:1957–1960.
Bello TR. Antiparasitic treatment of horses with pyrantel and fenbendazole followed by continual ivermectin treatments, in Proceedings. 35th Annu Meet Am Assoc Equine Pract 1989;419–429.
Bello TR. Alternative antiparasitic treatment of horses with pyrantel pamoate suspension and ivermectin oral solution compared with horses treated only with ivermectin oral solution. J Equine Vet Sci 1996;16:166–170.
Bello TR. Controlled test and clinical evaluation of dienbendazole against naturally acquired gastrointestinal parasites in ponies. Am J Vet Res 1989;50:1976–1980.
Bello TR. The control and treatment of internal equine parasites. Somerville, NJ: Monograph, American Hoechst Corp, 1981;1–19.
Morgan BB, Hawkins PA. Chapter 11: helminths of the horse. In: Veterinary helminthology. Minneapolis: Burgess Publishing Co, 1949;54–55.
Lucker JT. Comparative morphology and development of infective larvae of some horse strongyles, in Proceedings. Helminthol Soc Wash 1936;3:22–25.
Lucker JT. Description and differentiation of infective larvae of three species of horse strongyles, in Proceedings. Helminthol Soc Wash 1938;5:1–5.