In preliminary research, a regime dosing Exzolt at 0.5 mg/kg BW twice at a 7-day interval was identified as the most effective method for the treatment of induced red mite infestations on hens.1 This regime provided sufficient mite killing efficacy against D. gallinae for at least 15 days and was thus able to span the targeted 2 mite life cycles. Other single-dose treatments, even those of higher drug concentration, did not provide persistent efficacy for 15 days.
A second study evaluated only 2-dose regimes where Exzolt was administered at a 7-day interval at 0, 0.25, 0.5, or 1.0 mg/kg BW to hens artificially challenged with red mites1.
- A controlled, randomized dose-determination study. On day -12, hens were allocated to 4 treatment groups according to BW, 8 birds group.
- Exzolt treatments were administered via drinking water (first dose=day 0) as follows:
- Group A: untreated control group
- Group B: 0.25 mg fluralaner/kg BW/day twice 7 days apart
- Group C: 0.5 mg fluralaner/kg BW/day twice 7 days apart
- Group D: 1.0 mg fluralaner/kg BW/day twice 7 days apart
- Each hen was artificially infested with D. gallinae every 3 to 4 days until day 26.
- The numbers of dead, damaged, and live mites were counted 24 hours after each mite infestation to allow for determination of acaricidal effect.
- Mite mortality and inhibition were calculated for each treatment group at each time-point.
Efficacy assessment was based on percent of mite mortality for treated birds as compared to the negative controls, and the duration of high efficacy.
All 3 Exzolt treatment groups experienced high mite mortality and inhibition (most 100%) for 1 to 5 days after each dose, while only 2.7% mite mortality was observed in controls. The low-dose group (B, 0.25 mg/kg) did not provide suitable efficacy for 15 days. In contrast, Group C birds (0.5 mg/kg) demonstrated consistent 100% efficacy against red mites, providing complete mortality for 15 days (Figure 5-1). The high-dose group (D, 1.0 mg/kg) did not show a significant additional benefit to justify the greater dose.
The Exzolt dosage regime of 0.5 mg fluralaner/kg BW twice at a 7-day interval achieved 100% mite-killing efficacy for at least 15 days, thus meeting the target efficacy duration spanning 2 mite development cycles.
- Data on file. MSD Animal Health.