Moxidectin: veterinary dose and monograph

At a glance

Drug class

Antiparasitic

Also known as

Cydectin, ProHeart, Equest

Species with doses

Dogs, Cats, Cattle, Horses, Goats, Sheep and Camelids

General dose range

0.2–0.4 mg/kg SC single dose (per indication) — check the species tables for the indication

Routes

SC, Topical, PO

Last reviewed

1 October 2026

Indications

• GI roundworms, lungworms and arthropod parasites of cattle, sheep and goats
• Equine cyathostomes (incl. encysted larvae) and bots
• Canine heartworm prevention (sustained-release / combination products)
• Sarcoptic and demodectic mange (off-label)

Moxidectin 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

• Heartworm prevention / mange (off-label): Heartworm prevention (oral ~3 µg/kg monthly, or sustained-release ProHeart injection per label). ⚠ High off-label miticidal doses are neurotoxic in MDR1/ABCB1 breeds — test first.
• Heartworm / parasite prevention — TOPICAL spot-on: ⚠ FORMULATION-SPECIFIC: the topical moxidectin/imidacloprid spot-on (Advantage Multi / Coraxis) is applied at 2.5 mg/kg moxidectin monthly — roughly 800× the 3 µg/kg ORAL monthly dose, because dermal absorption is low. Papich 5th ed: "Topical heartworm prevention (Advantage Multi, or Coraxis) 2.5 mg/kg monthly." NEVER give the topical figure by mouth.
• Generalised demodicosis (off-label): Papich 5e p629: 200 mcg/kg SQ weekly or every other week for one to four doses; refractory cases 400-500 mcg/kg/day PO. Start low and escalate - avermectin-sensitive breeds (Collie, Australian Shepherd, ABCB1/MDR1 mutants) can develop severe neurotoxicity. Test MDR1 before high-dose use. (= 0.2–0.5 mg/kg.)
• Sarcoptic mange (off-label): Papich 5e: 200–250 µg/kg PO or SC once weekly for 3–6 weeks. Plumb’s p.866 (Foil 2003): 0.25 mg/kg SC every 7 days for 3 treatments, or 0.4 mg/kg PO every 3–4 days for 3–6 weeks. Toxic in ABCB1 (MDR1) mutant dogs — test first. (= 0.2–0.25 mg/kg.)
• Heartworm prevention - ProHeart 6 (sustained-release SC): Papich 5e p629: 6-month formulation 0.17 mg/kg SC. Give only the constituted sustained-release suspension by this route - never substitute an oral or topical product.
• Heartworm prevention - ProHeart 12 (sustained-release SC): Papich 5e p629: 12-month formulation 0.5 mg/kg SC. Sustained-release suspension only.

Cats

• Heartworm / parasite prevention — topical (with imidacloprid): Papich 5e and Plumb’s p.866 (Advantage Multi for Cats label): minimum 1 mg/kg moxidectin with 10 mg/kg imidacloprid topically every 30 days. Aelurostrongylus: 1–3 applications were effective (Conboy 2009). Formulation-specific — use the product dosing bands.

Cattle

• GI nematodes / mange (injection): Papich 5e and Plumb’s p.866 (Cydectin injection label): 0.2 mg/kg SC once (1 mL per 50 kg) in front of or behind the shoulder. Not for lactating dairy cattle or veal calves — check the local label withdrawal.
• GI nematodes (pour-on): Papich 5e and Plumb’s p.866 (Cydectin Pour-On label): 0.5 mg/kg (1 mL per 10 kg) along the back from withers to tail head, on healthy skin avoiding mange scabs. Avoid contact with human skin. Follow the local label for slaughter and milk withdrawal.

Horses

• Cyathostomes incl. encysted larvae: Papich 5e: 0.4 mg/kg PO — avoid in young foals, small ponies and debilitated horses (narrow margin). Plumb’s p.866: mucosal stages of small strongyles 400 µg/kg PO (Lyons & Drudge 2000). Dose accurately by weight.

Goats

• GI nematodes / mange (off-label): Plumb’s p.866 (Snyder 2009): goats — use twice the sheep dose (0.4 mg/kg PO) if moxidectin is deemed necessary. Extra-label — obtain a FARAD withdrawal.

Sheep

• GI nematodes (drench): Papich 5e and Plumb’s p.866 (Cydectin Oral Drench label): 0.2 mg/kg PO (1 mL of 1 mg/mL per 5 kg). Follow the local label withdrawal.

Buffalo

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

• GI nematodes / mange (injection): Papich 5e and Plumb’s p.866 (Cydectin injection label): 0.2 mg/kg SC once (1 mL per 50 kg) in front of or behind the shoulder. Not for lactating dairy cattle or veal calves — check the local label withdrawal.
• GI nematodes (pour-on): Papich 5e and Plumb’s p.866 (Cydectin Pour-On label): 0.5 mg/kg (1 mL per 10 kg) along the back from withers to tail head, on healthy skin avoiding mange scabs. Avoid contact with human skin. Follow the local label for slaughter and milk withdrawal.

Camelids

• GI nematodes: Plumb’s p.866 (Wolff 2009): oral ivermectin or moxidectin at 0.2 mg/kg is generally the regimen of choice for GI helminths in New World camelids.

Contraindications

MDR1 (ABCB1-1Δ) collies and related breeds at high (microfilaricidal or off-label) doses. Do not use bovine / equine concentrations in dogs. Observe withdrawal periods in food animals.

Species-specific warnings

Dogs: Use only canine-licensed products at canine doses. High off-label doses are neurotoxic in MDR1 / ABCB1 collies, Australian shepherds and related breeds.

Adverse effects

• Generally well tolerated at label dose
• MDR1 dogs: tremors, ataxia, mydriasis, coma at high doses
• Transient injection-site swelling

Drug interactions

• Plumb's p.867 records no moxidectin-SPECIFIC interactions; the following are extrapolated from ivermectin, a related compound
• Benzodiazepines: effects may be potentiated by moxidectin — combination not advised in humans
• P-glycoprotein inhibitors — the critical group. In dogs at risk of the ABCB1-1delta (formerly MDR1) mutation (Collies, Australian Shepherds, Shelties, Long-haired Whippets — the "white feet" breeds), moxidectin should probably NOT be combined with the drugs below unless the dog has tested normal
• ABCB1 risk list: amiodarone, carvedilol, clarithromycin, cyclosporine, diltiazem, erythromycin, itraconazole, ketoconazole, quinidine, spironolactone, tamoxifen, verapamil

Toxicity and overdose

Plumb's p.865: the margin of safety in dogs is very wide at label oral doses — up to 300x (1120 micrograms/kg) produced little or no effect, and ABCB1 wild-type dogs tolerated a single 200 mg/kg oral dose without neurologic toxicity. GENOTYPE IS EVERYTHING: dogs homozygous for the ABCB1 mutation have shown neurologic toxicity at just 90 micrograms/kg. Inadvertent overdoses during a demodicosis study produced dysorexia, hypersalivation, mydriasis, fasciculations and pelvic-limb ataxia. Of 172 exposures reported to the ASPCA APCC in 2005–2006 (171 dogs, 1 cat), 42 dogs showed clinical signs, tremors being the most common. Treatment is supportive; there is no specific antidote, though intravenous lipid emulsion has been used for macrocyclic lactone toxicosis.

Clinical pearls

• Longer persistent activity than ivermectin — extends the parasite-free interval on pasture
• Equine moxidectin gel is larvicidal against encysted cyathostomes — do not under-dose, but avoid in debilitated / very young foals
• Safer than ivermectin in MDR1 dogs at preventive doses, but high off-label miticidal doses are still neurotoxic — test the breed

Mechanism of action

Plumb's p.865: macrocyclic lactone (milbemycin). The primary action is on CHLORIDE ION CHANNELS in the nervous system of nematodes and arthropods — moxidectin binds receptors that increase membrane permeability to chloride, shutting down electrical activity in nematode nerve cells and arthropod muscle cells, causing paralysis and death. It also enhances presynaptic release of GABA, an inhibitory neurotransmitter that blocks post-synaptic stimulation of the adjacent neuron (nematodes) or muscle fibre (arthropods). Mammals are generally spared because they lack glutamate-gated chloride channels and because these compounds do not readily cross the blood-brain barrier, where mammalian GABA receptors sit — which is exactly why a defective barrier (the ABCB1-1delta mutation) converts a safe drug into a neurotoxic one.

Formulations and products

• Cydectin 1 % injection (10 mg/mL, cattle)
• Cydectin 0.5 % pour-on (5 mg/mL)
• Cydectin 0.1 % oral drench (1 mg/mL, sheep)
• Equest 2 % oral gel (20 mg/mL, horse)

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

• Milbemycin oxime
• Monensin
• Monepantel
• Morantel
• Nicarbazin
• Niclosamide
• Nitenpyram
• Nitroxynil

Frequently asked questions