Clinical Trial on the efficacy and safety of Fenbendazole oral suspension (Panacur, 10%) on donkeys naturally infected by intestinal Strongylidae.

Objectives Donkeys and horses share several internal parasites including the nematodes Strongylidae, subfamilies Strongylinae and Cyathostominae (also known as large and small strongyles, respectively). Fenbendazole (FBZ), a compound of benzimidazoles family, has a wide range of endoparasitic activity in many species and high margin of safety. When discovered, FBZ was shown to have excellent efficacy against small and large strongyles, Parascaris equorum and Oxyuris equi in horses (Riviere and Papich, 2009). FBZ formulations currently available in Italy for horses are 10% paste and 10% oral suspension. There is a paucity of data available on the efficacy of anthelmintics used in donkeys. Therapeutics, such as antiparasitic compounds, are often administered to donkeys on the basis of dosage and intervals recommended for horses and cattle, because very few drugs have donkey-specific label indications (Grosenbaugh et al, 2011). A higher metabolic capacity and lower absorption of benzimidazoles in donkeys decrease bioavailability and efficacy of compounds (Gokbulut et al., 2006). The aim of the present study was to evaluate the field efficacy and safety of FBZ 10% oral suspension at horse dose rate against natural infection of Strongylidae on donkeys. Materials and Methods The trial was conducted on a donkey farm in southern Italy. Faecal examinations (individual Faecal Egg Counts and pooled coprocolture) performed before the beginning of the study showed individual counts >150 eggs per gram (EPG) and high prevalence of intestinal nematodes (Cyathostomum spp., Triodontophorus spp., Poteriostomum spp., Strongylus spp.) in all donkeys in the farm. Fourteen female crossbreed donkeys, 230-350 body weight, were selected on the basis of positive faecal egg counts (FEC). The animals were allocated to two groups, each of 7 donkeys. One group was untreated control (C-group) and the other was treated (P-group) using FBZ (Panacur® 10% suspension, MSD) administered per os at the manufacturer???s recommended horse dose of 7.5 mg/kg b.w.. FECs were performed on each study animal before the start of the trial (Day -2), at Days 7, 14, 21, 28, 35, 42, 56 and 63 after treatment. FECs were determined by a modified McMaster technique (sensitivity 10 EPG). On each sampling day, faecal samples were incubated at 27 °C for 7-10 days for larval identification. Third stage larvae were identified using the keys proposed by MAFF (1986). To determine the efficacy of FBZ against intestinal strongyles following the WAAVP guidelines at each faecal sampling time, arithmetic mean of EPG was calculated and the percent efficacy (%) of each animal was calculated in terms of FEC Reduction (FECR) at the different days according to the formula: Results and Conclusions The animals were observed throughout the study. Clinically no adverse reaction was observed in any of the donkeys treated with FBZ oral formulation. The arithmetic mean (AM) of strongyle egg counts on day - 2 was 1,321 and 1,067 EPG in the C and P groups, respectively. After the treatment three donkeys in the P-Group were shedding eggs by day 42. By day 56 all treated donkeys were positive to strongyle eggs. However, FECR remained high throughout the study period. The percentage reductions in FEC from P group compared to C group were 100% on days 7, 14, 21, 28 and 35, 99.4% on day 42, 95.7% on day 49, 85.6% on day 56, and 67,5% on day 63 post treatment. The FBZ treatment in donkeys was efficient (>90% efficacy) until Day 49. In all studied donkeys, faecal cultures performed at day -2 revealed the presence of following genera Cyathostomum, Triodontophorus, Poteriostomum and Strongylus. Faecal cultures performed at different days from C-group confirmed the presence of the same genera. Coprocoltures from treated animals revealed the presence of few larvae of Cyathostomum spp.. This trial demonstrates that FBZ oral suspension at the manufacturer???s recommended horse dose was effective and safety for the treatment of intestinal strongyles on donkeys. Therefore, similar dosage regimens of FBZ could be used for horses or donkeys. References Gokbulut C, Akar F, McKellar QA, 2006. Plasma disposition and faecal excretion of oxfendazole, fenbendazole and albendazole following oral administration to donkeys. Vet J, 172, 166-172. Grosenbaugh DA, Reinemeyer CR, Figueiredo MD (2011). Pharmacology and therapeutics in donkeys. Equine Vet Educ, 23, 523-530. MAFF, 1986. Manual of Veterinary Parasitological Laboratory Techniques. Reference Book 418. Ministry of Agriculture. Fisheries and Food, HMSO, London. Riviere JE, Papich MG, 2009. Veterinary Pharmacology and Therapeutics. Wiley-Blackwell editors IX edition. M ean EPG Control Group ??? M ean EPG Treated Group M ean FECR (%) = x 100 EPG Control Group