# Halofuginone: veterinary dose and monograph > Halofuginone is a veterinary antiparasitic. An antiprotozoal (a quinazolinone alkaloid derivative) licensed for the PREVENTION and reduction of CRYPTOSPORIDIOSIS (Cryptosporidium parvum) diarrhoea in NEONATAL CALVES — a major cause of scours and a zoonosis. Indications include 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). This monograph lists 1 reference dose for cattle, each with route, frequency and source, plus meat and milk withdrawal periods for food animals. Source: https://vetmasterji.com/drugs/halofuginone · Last reviewed: 2026-10-01 ## 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 *Halofuginone doses for cattle* | Indication | Dose | Route | Frequency | Duration | Withdrawal | | --- | --- | --- | --- | --- | --- | | Cryptosporidiosis (calf) — prevention/treatment | 0.1 mg/kg | PO | q24h × 7 days | — | 13d slaughter | - 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. *Halofuginone doses for buffalo* | Indication | Dose | Route | Frequency | Duration | Withdrawal | | --- | --- | --- | --- | --- | --- | | Cryptosporidiosis (calf) — prevention/treatment | 0.1 mg/kg | PO | q24h × 7 days | — | 13d slaughter | - 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 > **Caution:** 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 > **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. ## Other antiparasitics - [Fenbendazole](https://vetmasterji.com/drugs/fenbendazole) - [Fipronil](https://vetmasterji.com/drugs/fipronil) - [Flumethrin](https://vetmasterji.com/drugs/flumethrin) - [Fluralaner](https://vetmasterji.com/drugs/fluralaner) - [Imidacloprid](https://vetmasterji.com/drugs/imidacloprid) - [Imidocarb Dipropionate](https://vetmasterji.com/drugs/imidocarb) - [Ivermectin](https://vetmasterji.com/drugs/ivermectin) - [Levamisole](https://vetmasterji.com/drugs/levamisole) ## Frequently asked questions ### What is the dose of Halofuginone for cattle? Reference doses for Halofuginone in cattle: 0.1 mg/kg PO q24h × 7 days (Cryptosporidiosis (calf) — prevention/treatment). Confirm against the label and the patient before use. ### What is the withdrawal period for Halofuginone? Cattle, PO (Cryptosporidiosis (calf) — prevention/treatment): 13d slaughter. Follow the product label and national regulations where they differ. ### When should Halofuginone not be used? 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. ### What are the side effects of Halofuginone in animals? 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. ## Sources - Plumb's Veterinary Drug Handbook - Merck Veterinary Manual, 11th edition - Papich, Papich Handbook of Veterinary Drugs, 5th edition --- 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.