Halofuginone: veterinary dose and monograph

At a glance

Drug class

Antiparasitic

Also known as

Halocur, Halofuginone lactate

Species with doses

Cattle

General dose range

0.1–0.125 mg/kg PO q24h — check the species tables for the indication

Routes

PO

Last reviewed

1 October 2026

Indications

• Prevention of Cryptosporidium parvum diarrhoea in neonatal calves (start <48 h of age, before scours)
• Reduction of cryptosporidial diarrhoea/oocyst shedding once scours have started
• Control of calf cryptosporidiosis outbreaks (with hygiene/rehydration)

Halofuginone 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.

Cattle

• Cryptosporidiosis (calf) — prevention/treatment: Label-sourced — neither Papich 5e nor Plumb’s has a halofuginone monograph. Halocur label: 100 µg/kg (2 mL per 10 kg of 0.5 mg/mL) PO once daily after feeding for 7 consecutive days; for prevention start within 24–48 h of birth, for treatment within 24 h of diarrhoea onset. Toxic at about twice the dose — never exceed; do not give on an empty stomach or to dehydrated/weak calves. Follow the local label withdrawal. (100 µg/kg = 0.1 mg/kg.)

Buffalo

No buffalo-specific doses are on file, so buffalo are dosed as cattle.

• Cryptosporidiosis (calf) — prevention/treatment: Label-sourced — neither Papich 5e nor Plumb’s has a halofuginone monograph. Halocur label: 100 µg/kg (2 mL per 10 kg of 0.5 mg/mL) PO once daily after feeding for 7 consecutive days; for prevention start within 24–48 h of birth, for treatment within 24 h of diarrhoea onset. Toxic at about twice the dose — never exceed; do not give on an empty stomach or to dehydrated/weak calves. Follow the local label withdrawal. (100 µg/kg = 0.1 mg/kg.)

Contraindications

Calves without milk/feeding intake (give after feeding) or that are severely dehydrated/anorexic (toxicity risk — rehydrate first). Overdosing (narrow margin — do not exceed ~2× dose). Calves under the label minimum age. Known hypersensitivity.

Species-specific warnings

Cattle: Narrow safety margin — overdose (≈2× dose) or use in a dehydrated/anorexic calf worsens scours and can be fatal. Dose precisely after feeding; rehydrate sick calves.

Adverse effects

• Narrow margin — overdose causes diarrhoea/worsening scours, anorexia, depression, and can be fatal
• GI irritation if given to an empty stomach
• Worsening of clinical signs if dosed in a dehydrated/sick calf

Drug interactions

• No major host drug interactions of note
• Concurrent management (oral rehydration, colostrum, hygiene) is essential adjunctive therapy

Pregnancy and lactation

Used in neonatal calves; not relevant to pregnancy. Narrow margin in the calf is the key safety issue.

Monitoring

• Calf hydration/clinical status BEFORE and during dosing (only dose hydrated, fed calves)
• Accurate body weight and dose (narrow margin)
• Diarrhoea/oocyst-shedding response; herd hygiene and colostrum management
• Meat withdrawal compliance

Toxicity and overdose

NARROW therapeutic index — toxicity (worsening diarrhoea, anorexia, depression, dehydration, potentially death) occurs at roughly twice the therapeutic dose or when given to compromised (dehydrated/anorexic/empty-stomach) calves. Accurate weight-based dosing and giving it after feeding to a hydrated calf are essential.

Management: No specific antidote. Discontinue; provide intensive supportive care — aggressive oral/IV rehydration and electrolyte/acid–base correction, nursing, and treat the scours symptomatically. Prevent by precise dosing and avoiding use in compromised calves.

Clinical pearls

• The licensed drug to PREVENT calf cryptosporidiosis — start within 24–48 h of birth, before scours, for best effect
• Mind the NARROW margin: dose precisely by weight, give AFTER feeding, and never to a dehydrated/anorexic calf (rehydrate first)
• It reduces but doesn't eliminate the parasite — combine with colostrum, oral rehydration and rigorous hygiene (Cryptosporidium is zoonotic)
• Use the supplied dosing syringe to avoid the easy, dangerous overdose

Mechanism of action

Halofuginone is a coccidiostatic/cryptosporidiostatic antiprotozoal that inhibits development of the free (sporozoite/merozoite) and intracellular stages of Cryptosporidium, reducing parasite multiplication and oocyst shedding. (Mechanistically it inhibits prolyl-tRNA synthetase/amino-acid-starvation responses, the basis of its antiprotozoal and antifibrotic activities.) It reduces, rather than eliminates, infection — so hygiene, colostrum and rehydration remain essential.

Formulations and products

• Oral solution 0.5 mg/mL (Halocur)
• Halocur (MSD Animal Health) — 0.5 mg/mL oral solution, Oral solution

Storage

Oral solution: 15–25 °C, protect from light; use the supplied dosing syringe for accuracy. Keep from children/animals (toxic).

Before you use this dose

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