Dr. Murai Éva szerk.: Parasitologia Hungarica 22. (Budapest, 1989)

MATERIALS AND METHODS 1. Experimental animals: The experiments were conducted on 178 colts between the age of 0.6-5 years, 3 stud horses between the age of 12-14, 80 stud mares between the age of 2-16, and 19 geldings between the age of 2-17 years, altogether 280 Nonius, Hungarian half-blood and Gidran sports stud horses in the period between 2 April 1985 and 18 April 1986. The horses were kept free in the tables. Experimental stud "A" contained mainlv Nonius while studs "B" and "C" had Kisbér half-blood, and Gidran horses (113, 81 and 86 animals respectively). l

n stud "A" Eqvalan paste (MSD) was used in 15 stud mares (2-3 years old). The same number of control animals did not get any treatment. The actual severity of Invasion with horse botfly larvae was unknown. However, earlier the author had established the numbers of botfly eggs laid on the horses ln each stud. 2. Drugs: We treated the horses with Strongid Plus paste i(Pfizer) and Eqvalan paste (MSD). Strongid Plus Is a smooth, pale yellow to buff-coloured, parsley-flavoured paste containing 190 mg/mL of pyrantel pamoate (equivalent to 66 mg/mL of pyrantel base) and 300 mg/mL of trichlorfon as active ingredients In a peanut oil vehicle. We treated horses with Strongid Relative frequency of larval excreti 120.0 L 114.0 108.0 j- 102.6 96.0 L 91.2 84.0 L 79.8 72.0 L 60.0 48.0 36.0 24.0 12.0 0.0 ! 68.4 57.0 L 45.61 34.2 22.8 11.4 ,DCL_ 0. 0 o o_p _o o 2 Eqv Str. a a • • o D «0 D• Go o • • o o • I o • o n

n late • c O o • Ç_o_oo_ecfo nJ* Time after application of medicaments Notes : • Str. - Strongid Plus 44 58 Eqv. = Eqvalan 72 hours Fig. 2. Temporal distribution of the periods of larva (L

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) excretion (G. intestinalis, G. pecorum) caused by Strongid Plus (Pfizer) and Eqvalan (MSD) by the method of multiple regression analysis