# Piperazine: veterinary dose and monograph

> Piperazine is a veterinary antiparasitic. One of the oldest, cheapest and safest anthelmintics — but NARROW spectrum: it is effective essentially only against ASCARIDS (large roundworms — Toxocara, Parascaris, Ascaridia) and not against hookworms, whipworms, tapeworms or most… Indications include ascarid (large roundworm) infections in dogs, cats, foals, pigs and poultry; routine roundworm deworming where only ascarids are targeted; deworming of young or debilitated animals needing a very-low-toxicity option. This monograph lists 7 reference doses for dogs, cats, horses, pigs, poultry and rabbits and 1 more species, each with route, frequency and source, plus meat and milk withdrawal periods for food animals.

Source: https://vetmasterji.com/drugs/piperazine · Last reviewed: 2026-10-01

## At a glance

- **Drug class:** Antiparasitic
- **Also known as:** Piperazine citrate, Pinworm syrup, Wormaway
- **Species with doses:** Dogs, Cats, Horses, Pigs, Poultry, Rabbits and Reptiles
- **General dose range:** 45–65 mg/kg PO single dose (repeat in 2–3 weeks) — check the species tables for the indication
- **Routes:** PO
- **Last reviewed:** 1 October 2026

## Indications

- Ascarid (large roundworm) infections in dogs, cats, foals, pigs and poultry
- Routine roundworm deworming where only ascarids are targeted
- Deworming of young or debilitated animals needing a very-low-toxicity option

## Piperazine dose by species

Doses are per administration unless stated. mg/kg doses scale with body weight; per-animal, per-quarter and infusion-rate doses are shown as the reference writes them.

### Dogs

*Piperazine doses for dogs*

| Indication | Dose | Route | Frequency | Duration |
| --- | --- | --- | --- | --- |
| Ascarids (roundworms) | 45–65 mg/kg | PO | single dose | — |

- Ascarids (roundworms): Papich 5e: 44–66 mg/kg PO once. Plumb’s p.982: 45–65 mg/kg of base PO (pups under 2.5 kg max 150 mg) (Cornelius & Roberson); other sources 100–110 mg/kg. Salts contain different amounts of base — check the product. Repeat in 2–3 weeks (larvae in tissues are unaffected).

### Cats

*Piperazine doses for cats*

| Indication | Dose | Route | Frequency | Duration |
| --- | --- | --- | --- | --- |
| Ascarids | 45–65 mg/kg | PO | single dose | — |

- Ascarids: Papich 5e: 44–66 mg/kg PO once. Plumb’s p.982: 45–65 mg of base/kg (maximum 150 mg in kittens); 100–110 mg/kg in other sources. Repeat in 2–3 weeks.

### Horses

*Piperazine doses for horses*

| Indication | Dose | Route | Frequency | Duration |
| --- | --- | --- | --- | --- |
| Parascaris equorum (foals) | 110 mg/kg | PO | single dose | — |

- Parascaris equorum (foals): Papich 5e: horses and pigs 110 mg/kg PO (or 30 mL of 17% solution per 45 kg). Plumb’s p.982 (Roberson 1988): 110 mg/kg (base) PO, repeat in 3–4 weeks; 10-weekly retreatment for P. equorum in young horses. Heavy burdens risk impaction when killed en masse.

### Pigs

*Piperazine doses for pigs*

| Indication | Dose | Route | Frequency | Duration | Withdrawal |
| --- | --- | --- | --- | --- | --- |
| Ascaris suum | 110 mg/kg | PO | single dose | — | Withdrawal NOT established — treat as extra-label |

- Ascaris suum: Papich 5e: horses and pigs 110 mg/kg PO in the drinking water as the sole water source. Plumb’s (swine): 110 mg/kg as base — citrate usually in feed as a one-day treatment, hexahydrate in water; the dose must be consumed within 8–12 h (withhold feed or water overnight); retreat in 2 months. Plumb’s notes swine withdrawal times are not determined — follow the product label.

### Poultry

*Piperazine doses for poultry*

| Indication | Dose | Route | Frequency | Duration | Withdrawal |
| --- | --- | --- | --- | --- | --- |
| Ascaridia galli | 32 mg/kg | PO | two successive feedings (or 2 days in water) | — | Withdrawal NOT established — treat as extra-label |

- Ascaridia galli: Plumb’s p.982 (Roberson 1988): 32 mg/kg as base (~0.3 g per adult bird) in each of 2 successive feedings or for 2 days in drinking water; poultry 100–500 mg/kg once, repeat in 10–14 days (Clubb 1986). Not effective in psittacines. Follow the product-label withdrawal.

### Rabbits

*Piperazine doses for rabbits*

| Indication | Dose | Route | Frequency | Duration |
| --- | --- | --- | --- | --- |
| Pinworms (Passalurus) | 100 mg/kg | PO | q24h | 2 days |

- Pinworms (Passalurus): Plumb’s p.982 (Ivey & Morrisey 2000): piperazine citrate 100 mg/kg PO q24h for 2 days (adipate 200–500 mg/kg in adults); or 3 g/L in drinking water for 2 weeks (Burke). Wash the perianal area.

### Reptiles

*Piperazine doses for reptiles*

| Indication | Dose | Route | Frequency | Duration |
| --- | --- | --- | --- | --- |
| Nematodes | 40–60 mg/kg | PO | repeat in 2 weeks until faecal negative | — |

- Nematodes: Plumb’s p.982 (de la Navarre 2008): 40–60 mg/kg PO, repeat in 2 weeks, faecal check 14 days later.

## Contraindications

Severe hepatic or renal impairment (reduced clearance — neurotoxicity risk). Gastrointestinal obstruction or impaired motility (relies on normal peristalsis to expel paralysed worms; heavy ascarid burdens can cause obstruction as worms detach). Chronic use. Known hypersensitivity.

## Species-specific warnings

> **Caution:** Horses: Heavy Parascaris burdens in foals can impact/obstruct the small intestine when worms are killed — consider a less abrupt approach in known heavy infections.

## Adverse effects

- Generally minimal — occasional vomiting/diarrhoea
- Neurotoxicity (ataxia, tremor) at overdose or with impaired clearance
- Possible obstruction with very heavy ascarid burdens (worm bolus)

## Drug interactions

- Pyrantel/morantel/levamisole (spastic-paralysis agents): pharmacologically antagonistic (flaccid vs spastic paralysis) — do not combine
- Chlorpromazine/phenothiazines: increased risk of neurotoxicity/seizures (reported)
- Purgatives: historically combined to aid expulsion (rarely needed)

## Pregnancy and lactation

Considered safe in pregnancy at label doses (very low toxicity).

## Monitoring

- Faecal egg count (ascarids) and repeat dosing at 2–3 weeks
- For heavy burdens (foals), watch for colic/impaction after treatment
- Neurologic signs if hepatic/renal impairment

## Toxicity and overdose

Extremely wide safety margin; overdose can cause reversible neurotoxicity (ataxia, muscle tremor, head pressing) especially with hepatic/renal impairment. Massive ascarid kill can rarely cause GI obstruction.

Management: Supportive — neurologic signs are usually reversible with discontinuation and time; fluids and nursing care. No specific antidote. Manage any obstruction surgically/medically as needed.

## Clinical pearls

- Cheap, OTC and extremely safe — but it ONLY kills ascarids; it misses hookworms, whipworms and tapeworms
- Works by flaccid paralysis (GABA agonist) — never combine with pyrantel/levamisole (spastic paralysis): they cancel out
- In heavily parasitised foals, mass worm death can cause impaction — deworm thoughtfully
- Largely superseded by broad-spectrum dewormers, but handy for a quick, safe ascarid clean-out in young animals

## Mechanism of action

Acts as a GABA-receptor agonist at the nematode neuromuscular junction, hyperpolarising muscle and causing flaccid paralysis of the worm. The paralysed (but living) ascarids lose their grip on the gut wall and are expelled by normal intestinal peristalsis — which is why adequate gut motility is needed and why a massive worm load can occasionally cause obstruction.

## Formulations and products

- Oral syrup/solution (various strengths)
- Oral powder (water/feed)
- Tablet
- Piperazine syrup/powder (vet) (Various (India)) — Piperazine citrate/adipate, Syrup / powder / tablet
- Piperazine citrate (pinworm/roundworm syrup) — Syrup, Oral syrup (human-label)

## Storage

Syrup/powder/tablets: 15–30 °C, protect from light; keep tightly closed.

## Before you use this dose

> **Caution:** Reference doses for veterinary professionals. Confirm the dose against the product label, the patient’s condition, current guidance and local regulations before use; the attending veterinarian remains responsible for every clinical decision.

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## Frequently asked questions

### What is the dose of Piperazine for dogs?

Reference doses for Piperazine in dogs: 45–65 mg/kg PO single dose (Ascarids (roundworms)). Confirm against the label and the patient before use.

### What is the dose of Piperazine for cats?

Reference doses for Piperazine in cats: 45–65 mg/kg PO single dose (Ascarids). Confirm against the label and the patient before use.

### What is the dose of Piperazine for horses?

Reference doses for Piperazine in horses: 110 mg/kg PO single dose (Parascaris equorum (foals)). Confirm against the label and the patient before use.

### What is the withdrawal period for Piperazine?

Pigs, PO (Ascaris suum): Withdrawal NOT established — treat as extra-label; Poultry, PO (Ascaridia galli): Withdrawal NOT established — treat as extra-label. Follow the product label and national regulations where they differ.

### When should Piperazine not be used?

Severe hepatic or renal impairment (reduced clearance — neurotoxicity risk). Gastrointestinal obstruction or impaired motility (relies on normal peristalsis to expel paralysed worms; heavy ascarid burdens can cause obstruction as worms detach). Chronic use. Known hypersensitivity.

### What are the side effects of Piperazine in animals?

Generally minimal — occasional vomiting/diarrhoea; Neurotoxicity (ataxia, tremor) at overdose or with impaired clearance; Possible obstruction with very heavy ascarid burdens (worm bolus).

## Sources

- Plumb's Veterinary Drug Handbook
- Merck Veterinary Manual, 11th edition
- Papich, Papich Handbook of Veterinary Drugs, 5th edition

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VetMasterJi is a clinical decision-support and education platform for veterinary professionals and students. It does not provide veterinary advice, diagnosis or treatment for specific animals. All drug doses, calculators and differentials are references that must be independently verified before clinical use; the attending registered veterinarian remains solely responsible for every clinical decision.