Diclazuril: veterinary dose and monograph

At a glance

Drug class

Antiparasitic

Also known as

Vecoxan, Clinacox, Protazil

Species with doses

Dogs, Cats, Cattle, Horses, Sheep and Poultry

General dose range

1 mg/kg PO single dose (ruminants) / continuous (poultry) — check the species tables for the indication

Routes

PO

Last reviewed

1 October 2026

Indications

• Coccidiosis (Eimeria) in calves, lambs and kids — treatment/prevention
• Poultry coccidiosis (in-feed coccidiostat)
• Equine protozoal myeloencephalitis (EPM) — Sarcocystis neurona (Protazil)

Diclazuril 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

• Coccidiosis: Plumb’s p.389 (Greene 2006): dogs and cats 25 mg/kg PO once.

Cats

• Coccidiosis (Isospora): Plumb’s p.389: 25 mg/kg PO once (Greene 2006; Dubey 2009); kittens 1 mL (2.5 mg) of the sheep suspension per 4 kg (Miller 2007).

Cattle

• Coccidiosis (calves): Plumb’s p.389 (Vecoxan UK label): 1 mg/kg (1 mL of 2.5 mg/mL per 2.5 kg) PO once, 14 days after moving into a high-risk environment; treat all calves in the pen.

Horses

• EPM (Sarcocystis neurona): Papich 5e and Plumb’s p.389 (Protazil label): 1 mg/kg top-dressed on feed daily for 28 days (at steady state 0.5 mg/kg gives similar levels). Prevention (Papich): 0.5 mg/kg every 3–4 days.

Goats

• No reference dose for this species: Neither Papich 5e nor Plumb’s gives a diclazuril dose for goats (Plumb’s lists lambs and calves only); the previous row copied the lamb dose.

Sheep

• Coccidiosis (lambs): Plumb’s p.389 (Vecoxan UK label): 1 mg/kg PO once — preventively at 4–6 weeks of age, with a second dose about 3 weeks later under high infection pressure; treat all lambs.

Poultry

• Coccidiosis (in feed): Dosed by feed concentration (~1 ppm) per label.

Buffalo

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

• Coccidiosis (calves): Plumb’s p.389 (Vecoxan UK label): 1 mg/kg (1 mL of 2.5 mg/mL per 2.5 kg) PO once, 14 days after moving into a high-risk environment; treat all calves in the pen.

Contraindications

Known hypersensitivity. Verify food-animal withdrawal per product. Otherwise few — wide safety margin. Ensure correct diagnosis (coccidiosis vs other enteritis; EPM confirmation in horses).

Species-specific warnings

Horses: Used for EPM (Sarcocystis neurona) — neurologic signs may transiently worsen early in treatment; confirm diagnosis and consider anti-inflammatory support.

Adverse effects

• Generally very well tolerated
• Rare GI upset
• EPM treatment: transient worsening of neurologic signs early (parasite die-off) is possible

Drug interactions

• No clinically important systemic drug interactions reported
• In EPM, sometimes used in protocols with anti-inflammatories to manage die-off inflammation

Pregnancy and lactation

Considered safe at label doses in breeding/pregnant animals; widely used in young stock.

Monitoring

• Faecal oocyst counts / clinical response (coccidiosis)
• Neurologic improvement over the course (EPM)
• Withdrawal-period compliance (poultry)

Toxicity and overdose

Very wide safety margin — overdose is generally well tolerated with at most mild GI signs. No significant target-organ toxicity at therapeutic or modest supratherapeutic doses.

Management: Supportive only; no specific antidote required given the wide margin. Symptomatic care for any GI upset.

Clinical pearls

• A convenient SINGLE-DOSE oral coccidiocide for calves, lambs and kids — good for outbreak control
• Very wide safety margin — one of the better-tolerated anticoccidials
• In horses it is an EPM treatment (Protazil) — confirm the diagnosis and watch for early die-off worsening
• For prevention, time dosing to the expected pre-patent period of the Eimeria challenge

Mechanism of action

A triazine antiprotozoal that acts on the apicomplexan parasite (Eimeria/Sarcocystis), disrupting development of the asexual and sexual intracellular stages — interfering with the apicoplast/organellar function and halting schizogony and gametogony. This both treats active infection and prevents oocyst shedding. The same class action underlies its efficacy against Sarcocystis neurona in EPM.

Formulations and products

• Oral suspension 2.5 mg/mL (Vecoxan)
• Feed premix (Clinacox, poultry)
• Oral pellets / paste (equine EPM, Protazil)
• Vecoxan (Elanco) — Diclazuril 2.5 mg/mL oral suspension, Oral suspension
• Protazil (Merck Animal Health) — 1.56 % diclazuril pellets, Oral pellets

Storage

Suspension/pellets/premix: 15–30 °C, dry, protect from light; shake suspension before use.

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

• Cypermethrin
• Decoquinate
• Deltamethrin
• Dichlorvos (DDVP)
• Diethylcarbamazine (DEC)
• Diminazene Diaceturate
• Doramectin
• Emodepside

Frequently asked questions