Administering Exzolt in Young Chicks

The study involved 320 broiler chicks that were 3 weeks of age at the start of dosing. The results showed that Exzolt was well tolerated and "normally palatable" in these young birds, even when administered at 5 times the recommended dose for 3 times the recommended frequency. The study concluded there were no adverse effects on the chicks' body weight, feed consumption, or general health.

Additionally, the Exzolt Technical Manual (often linked in the resources section of that site) notes that because of these safety margins, there is technically no specific age restriction for its use in chickens.

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A similar pivotal study involving young chickens evaluated the safety Exzolt treatment via drinking water when administered at 0 (control), 1-, 3-, or 5-times the recommended dose (0, 0.5, 1.5, or 2.5 mg fluralaner/kg BW, respectively) for 3-times the recommended frequency (6 treatments instead of 2), for a total overall dosage up to 15-times the recommended dose (Figure 4-2).²

• 320 broiler male and female chicks (3 weeks of age at start of dosing) were randomly allocated to 4 treatment groups of 80 birds.
• The 3 treated groups were offered tap water medicated with Exzolt as described in Figure 4-2 on 6 occasions at weekly intervals (days 0, 7, 14, 21, 28, 35) while control group birds received non-medicated water. (As a result, the total net doses of fluralaner administered were 3-times, 9-times, or 15-times the recommended total dose.)
• Clinical health was monitored throughout the 54-day study, feed and water intakes were recorded, and pen body weights were obtained weekly. Hematology and clinical chemistry parameters were measured pre-treatment and at multiple time-points.
• Ten birds per group were euthanized on days 36 and 54 for complete gross necropsy, and complete histopathological examination was performed on organs from the control and the highest dose (5-times) group.
• Data collections were performed by personnel blinded to treatment.

RESULTS

No clinically significant or relevant differences for any safety or toxicological parameters were detected between the control group and all medicated groups, including birds treated at the 5-times dose rate. The mortality rate per pen was similar for all groups, and treatments had no effect on BW or rates of feed consumption by chicks. Thus, use of Exzolt even at such extreme levels was not associated with any clinical, gross, or microscopic findings, productivity not measured.

Water intake was similar between all treatment groups, indicating that normal palatability was maintained for drinking water medicated with Exzolt.

CONCLUSION

This target animal safety study demonstrated that Exzolt is well tolerated and normally palatable in chicks and growing chickens, even when grossly overdosed at up to 5-times the recommended dose rate for 3-times the recommended frequency (6 occasions at 7-day intervals). Use of Exzolt at the recommended daily dose rate of 0.5 mg/kg BW twice at a 7-day interval clearly offers a wide margin of safety for growing chickens and does not impact water consumption.

Source - Exzolt Website - Safety in Chickens