Toltrazuril: veterinary dose and monograph

At a glance

Drug class

Antiparasitic

Also known as

Baycox

Species with doses

Dogs, Cats, Cattle, Horses, Sheep, Pigs, Birds and Reptiles

General dose range

7–20 mg/kg PO single dose (repeat in 1–2 wk if needed) — check the species tables for the indication

Routes

PO

Last reviewed

1 October 2026

Indications

• Coccidiosis in calves, lambs and kids (Eimeria)
• Neonatal porcine coccidiosis (Cystoisospora suis)
• Canine / feline cystoisosporosis
• Poultry coccidiosis (in-water)

Toltrazuril 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

• Cystoisospora (pups): Papich 5e: puppies 10–30 mg/kg q24h PO for 3 days. Plumb’s p.1134: 10–20 mg/kg once to all puppies at 3–4 weeks of age (Daugschies 2000); 10–30 mg/kg once daily for 1–3 days (Dubey 2009); 15 mg/kg once daily for 3–6 days; 20 mg/kg once daily for 3 days (Marks 2007).

Cats

• Coccidiosis (kittens): Papich 5e: 30 mg/kg once or 15 mg/kg once daily for 3 days, repeated 10 days later. Plumb’s p.1134: 30 mg/kg once daily for 2–3 days (Greene 2006); 20 mg/kg once daily for 3 days (Marks 2007).
• Toxoplasma oocyst shedding: Papich 5e and Plumb’s p.1134 (Dubey & Lappin 2006): 5–10 mg/kg PO once daily for 2 days.

Cattle

• Coccidiosis (calves, metaphylaxis): Product label (toltrazuril 50 mg/mL for calves): 15 mg/kg PO once. Plumb’s 10e p.1256 (extra-label) gives the same: prevention of coccidiosis (Eimeria bovis / E. zuernii) in calves on farms with a confirmed history — 15 mg/kg PO once per animal, dosed by the heaviest animal in a group, before expected onset of signs; not for calves over 80 kg, fattening (veal/beef) units or dairy animals. Papich 5e gives no cattle dose. Long meat withdrawal (63 days on the EU label) — verify against the local label; not for calves producing veal or cattle whose milk is used.

Horses

• EPM (Sarcocystis neurona): Papich 5e: 5–10 mg/kg (7.5 mg/kg for most horses) q24h PO for a minimum of 30 days.

Goats

• No reference dose for this species: Neither Papich 5e nor Plumb’s 10e (pp.1255–1257 dose sheep but not goats) gives a toltrazuril dose for goats; the previous row copied the lamb dose.

Sheep

• Coccidiosis (lambs): Plumb’s p.1134 (Mundt 2009): ovine coccidiosis (Eimeria ovinoidalis) 20 mg/kg PO once. Observe the product-label meat withdrawal.

Pigs

• Cystoisospora suis (piglets): Product label (toltrazuril 50 mg/mL for piglets): 20 mg/kg PO once at 3–5 days of age. Plumb’s 10e p.1257 (extra-label): preclinical coccidiosis due to Isospora suis in neonatal piglets — 20 mg/kg PO once at 3 to 4 days of age; weigh 3 representative litters at 3 days to set an average piglet weight. Papich 5e gives no pig dose. Observe the label meat withdrawal.

Buffalo

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

• Coccidiosis (calves, metaphylaxis): Product label (toltrazuril 50 mg/mL for calves): 15 mg/kg PO once. Plumb’s 10e p.1256 (extra-label) gives the same: prevention of coccidiosis (Eimeria bovis / E. zuernii) in calves on farms with a confirmed history — 15 mg/kg PO once per animal, dosed by the heaviest animal in a group, before expected onset of signs; not for calves over 80 kg, fattening (veal/beef) units or dairy animals. Papich 5e gives no cattle dose. Long meat withdrawal (63 days on the EU label) — verify against the local label; not for calves producing veal or cattle whose milk is used.

Birds

• Coccidiosis: Plumb’s p.1134 (Jones 2004): raptors 7 mg/kg PO once daily for 2–3 days. Poultry products are dosed in drinking water per label; observe egg and meat withdrawal.

Reptiles

• Coccidiosis (bearded dragons): Plumb’s p.1134 (Kramer 2006): bearded dragons 5–15 mg/kg PO once daily for 3 days.

Contraindications

No major contraindications at label dose. Observe meat withdrawal in food animals. Not for animals producing milk for human consumption (residues).

Adverse effects

• Generally minimal — occasional transient soft stool
• High doses: reduced appetite

Drug interactions

• No drug interactions are documented for toltrazuril in the uploaded references — Plumb's carries no Drug Interactions section for this drug, so nothing is asserted here rather than borrowing ponazuril's
• Cross-sensitivity: avoid in animals that have previously reacted to other triazinone (triazine) antiprotozoals — ponazuril or diclazuril

Toxicity and overdose

Plumb's p.1133 carries no Overdosage/Acute Toxicity section for toltrazuril, so no acute toxic dose is asserted here. Two documented cautions do apply: it is contraindicated after prior hypersensitivity to toltrazuril or other triazinone antiprotozoals (ponazuril, diclazuril); and the principal metabolite reportedly PERSISTS IN THE ENVIRONMENT and can contaminate groundwater, though Plumb's judges the risk low when used in dogs, cats and horses rather than at livestock or poultry scale.

Clinical pearls

• Dose just BEFORE the expected patency period — metaphylaxis prevents the production losses of clinical coccidiosis
• A single dose treats all intracellular stages — unlike sulfonamides it is not merely coccidiostatic
• Respect the long meat withdrawal (often ~63 days in cattle) — a common residue pitfall

Mechanism of action

Plumb's p.1133: TRIAZINONE (triazine) antiprotozoal. Toltrazuril is the PARENT compound of ponazuril — ponazuril is toltrazuril sulfone, its principal active metabolite. The mechanism is not well understood but it appears to inhibit protozoal enzyme systems. Active against Hepatozoon, Isospora (Cystoisospora), Sarcocystis, Toxoplasma and ALL intracellular stages of coccidia — activity against every intracellular stage is what allows a one- or two-dose course rather than prolonged treatment. About 50% absorbed orally in poultry, with highest concentrations in liver, where it is rapidly metabolised to ponazuril.

Formulations and products

• Baycox 5 % oral suspension (50 mg/mL)
• Baycox 2.5 % oral solution (25 mg/mL, poultry)

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.

Other antiparasitics

• Ronidazole
• Sarolaner
• Selamectin
• Spinosad
• Triclabendazole

Frequently asked questions