Piperazine is the only FDA approved dewormer for use in laying hens in the United States. It is only effective against the adult large roundworm. It has no effect on any other species of worms, including tapeworms.
Piperazine can be given orally by mouth in each bird, or added to the flock’s water source. Treatment needs to be repeated in 7-10 days since the drug does not kill the large roundworm eggs.
Egg Withdrawal Period:
- If given by mouth: 50 mg/bird (if younger than 6 weeks of age), otherwise 100 mg/bird (if older than 6 weeks of age), or according to the manufacturer label. Repeat in 7-10 days.
- If added to flock water source: 3 mL per gallon of water, or in accordance with the manufacturer’s label. Repeat in 7-10 days.
In Australia and Canada, piperazine is approved for 1-time use in egg laying hens at doses ranging from 130 to 200 mg/kg (59 to 91 mg/lb) with a 0-day egg withdrawal.
Unless otherwise specified by the manufacturer, piperazine products should be stored at room temperature (15-30°C).
Acute massive overdosage can lead to paralysis and death, but the drug is generally considered to have a wide margin of safety. The oral LD50 of piperazine adipate in mice is 11.4 g/kg.