Ivermectin: veterinary dose and monograph

At a glance

Drug class

Antiparasitic

Also known as

Ivomec, Heartgard, Eqvalan, Equimectrin

Species with doses

Dogs, Cats, Cattle, Horses, Goats, Sheep, Pigs, Birds, Rabbits, Ferrets, Reptiles and Camelids

General dose range

0.006–0.4 mg/kg PO depends on indication — check the species tables for the indication

Routes

PO, SC, Topical, IM

Last reviewed

1 October 2026

Indications

• Canine heartworm prophylaxis
• Demodicosis (off-label, MDR1-tested only)
• Sarcoptic mange / Cheyletiella / Otodectes
• Bovine GI roundworms, lungworms, grubs, mites, lice
• Equine strongyles, ascarids, bots, pinworms, summer sores
• Swine roundworms, lungworms, lice, mange
• Sheep/goat GI nematodes
• Avian ascarids, scaly-face mites (Knemidocoptes)

Ivermectin 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 prophylaxis: Papich 5e: 6 µg/kg every 30 days PO. Plumb’s p.686: 6–12 µg/kg PO once monthly (Knight); label minimum 6 µg/kg (Heartgard). Safe at this dose even in MDR1 (ABCB1) breeds.
• Microfilaricide (post-adulticide): Plumb’s p.686 (Kittleson 2006): 50 µg/kg (≈10× the preventive dose) gives a rapid microfilarial kill with more adverse reactions; the 6 µg/kg preventive dose clears microfilariae gradually over months with minimal risk. Pre-treat with an antihistamine ± corticosteroid and observe for 8 h. Not in MDR1 breeds.
• Demodicosis (TEST FOR MDR1 FIRST): Papich 5e: start 0.1 mg/kg/day and increase by 0.1 mg/kg/day to 0.6 mg/kg/day PO for 60–120 days. Plumb’s p.686: day 1 100 µg/kg, day 4 200, day 7 300, then +100 µg/kg every 3rd day to 600 µg/kg daily, continuing 1–2 months past two negative scrapes (Hillier); a 0.3–0.6 mg/kg regimen (Waisglass). Only in dogs tested normal/normal for the ABCB1 (MDR1) mutation; stop at any ataxia, mydriasis or lethargy.
• Sarcoptic mange: Papich 5e: 200–400 µg/kg PO every 7 days or SC every 14 days for 4–6 weeks. Plumb’s p.686 (Foil 2003): 300–400 µg/kg PO or SC once weekly. The 1% injectable is 10,000 µg/mL — dilute for small dogs. Not in MDR1 breeds (“white feet, don’t treat”); check heartworm status first.

Cats

• Heartworm prophylaxis: Papich 5e and Plumb’s p.686 (Knight 1995): 24 µg/kg PO every 30–45 days (also controls hookworms).
• Aelurostrongylus abstrusus (lungworm): Plumb’s p.686 (Reinemeyer 1995; Hawkins 2000): 0.4 mg/kg SC once. Papich 5e: cat endoparasites 0.2–0.4 mg/kg weekly SC or PO; ear mites 0.5 mL of 0.1 mg/mL per ear.

Cattle

• GI nematodes / lungworms / grubs / lice / mange — INJECTABLE: Papich 5th ed p.519: injection solution 200 µg/kg (0.2 mg/kg) SC as a single dose. No milk withdrawal established; not for breeding-age dairy cattle.
• GI nematodes / ectoparasites — POUR-ON (different dose!): ⚠ The pour-on is dosed at 0.5 mg/kg — 2.5× the injectable dose. Papich 5th ed p.519: "Pour-on: 0.5 mg/kg or 1 mL/10 kg (22 lb) of 5 mg/mL solution." Applying the 0.2 mg/kg injectable figure to a pour-on under-doses the animal by 2.5×. Apply along the topline.

Horses

• Strongyles / ascarids / bots / lungworms (oral paste): Papich 5e and Plumb’s p.686 (Eqvalan label): 200 µg/kg (0.2 mg/kg) PO as paste or oral liquid (oral liquid 1 mL per 50 kg); lice and mange 0.2 mg/kg PO at 4-day intervals (Robinson). Not for IM use in horses (clostridial myositis).

Goats

• GI nematodes (extra-label): Plumb’s p.688 (Upson 1988) and Papich 5e: goats 200 µg/kg (0.2 mg/kg) SC as a single dose. Goats clear ivermectin faster than cattle; observe an extended withdrawal (extra-label).

Sheep

• GI nematodes (sheep drench): Papich 5e: sheep 200 µg/kg PO (drench) or SC as a single dose. Plumb’s p.688: 200 µg/kg for nasal bots (Bennett); 200 µg/kg SC (Upson). US drench label slaughter withdrawal 11 days; not for ewes producing milk for human consumption.

Pigs

• GI roundworms / lungworms / lice / mange: Papich 5e and Plumb’s p.686 (Ivomec for Swine label): 300 µg/kg (0.3 mg/kg) SC in the neck behind the ear once; pot-bellied pigs repeat in 10–14 days for ectoparasites (Braun). US label slaughter withdrawal 18 days.

Buffalo

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

• GI nematodes / lungworms / grubs / lice / mange — INJECTABLE: Papich 5th ed p.519: injection solution 200 µg/kg (0.2 mg/kg) SC as a single dose. No milk withdrawal established; not for breeding-age dairy cattle.
• GI nematodes / ectoparasites — POUR-ON (different dose!): ⚠ The pour-on is dosed at 0.5 mg/kg — 2.5× the injectable dose. Papich 5th ed p.519: "Pour-on: 0.5 mg/kg or 1 mL/10 kg (22 lb) of 5 mg/mL solution." Applying the 0.2 mg/kg injectable figure to a pour-on under-doses the animal by 2.5×. Apply along the topline.

Birds

• Ascarids / scaly-face mites (most species): Plumb’s p.688: most birds 200–220 µg/kg IM, PO or SC, repeated in 10–14 days — dilute the 10 mg/mL bovine product (1:4 in propylene glycol, or to 2 mg/mL) and use immediately (Stunkard; Clubb; Sikarskie). Budgerigars 0.01 mL of the diluted product; finches 0.02 mg. Undiluted product is toxic to small birds.

Rabbits

• Psoroptes cuniculi (ear mites) / sarcoptic / cheyletiella: Plumb's extra-label: 0.2–0.4 mg/kg SC every 14 days × 2–3 doses. Standard rabbit ear-mite therapy.

Ferrets

• Heartworm prevention: Plumb's p.687 (Hoeffer 2000): heartworm prevention 0.02 mg/kg (20 µg/kg) PO monthly. Mange/ear mites extra-label 0.2–0.4 mg/kg SC repeated in 14 days.

Reptiles

• Nematodes / mites (lizards, snakes, alligators ONLY): Plumb's p.688 (Gauvin 1993): lizards, snakes and alligators 0.2 mg/kg IM, SC or PO once, repeat in 2 weeks. ⚠ FATAL in chelonians (turtles/tortoises), indigo snakes and skinks — do NOT use in these.

Camelids

• GI helminths (new world camelids): Plumb’s p.688 (Cheney & Allen 1989; Wolff 2009): 0.2 mg/kg PO or SC once. Meningeal worm (P. tenuis): 0.3 mg/kg SC once daily for 5 days with fenbendazole 50 mg/kg PO daily for 5 days (Edmondson 2009); give GI-ulcer prophylaxis.

Contraindications

ABSOLUTE CONTRAINDICATION in dogs with ABCB1-1Δ (MDR1) mutation (Collies, Shelties, Australian Shepherds and crosses) at non-preventive doses — fatal neurotoxicity. Test before use. Toxic in chelonians, indigo snakes, skinks. Foals <4 months. Cats: high dose causes neurotoxicity.

Species-specific warnings

Dogs: MDR1 (ABCB1) homozygous-mutant breeds (Collies, Aussies, Shelties, OES, etc.) — NEVER use high-dose ivermectin without genetic test. Heartgard preventive dose (6 µg/kg) is safe even in mutants.

Cats: Cats tolerate prevention doses (24 µg/kg PO monthly for HW) but are sensitive at >300 µg/kg. Use feline-labelled products only.

Horses: Safe at 200 µg/kg PO. Foals (>4 weeks) tolerate it. Encysted small strongyles require moxidectin — ivermectin doesn't reach them.

Cattle: Strict slaughter (35 d) and dairy (some EU jurisdictions: PROHIBITED in dairy) withdrawal. Pour-on residues can persist on hide — verify before slaughter.

Reptiles: TORTOISES, TURTLES, CHELONIANS — NEVER. Uniformly fatal even at "safe" mammalian doses. Other reptiles also sensitive — fenbendazole is the antiparasitic of choice.

Birds: Caged birds tolerate 200 µg/kg PO/SC for mites. Finches and small softbills are more sensitive — use lower dose with hydration support.

Adverse effects

• Neurotoxicity (mydriasis, ataxia, tremors, coma) — MDR1 dogs, overdose, exotic species
• Microfilariae kill reaction (shock-like) in heartworm-positive dogs
• Equine ventral midline pruritus 24 h post-dose (Onchocerca microfilariae)
• Cattle: paralysis from killing grubs in vertebral canal (treat outside risk season)
• Local injection-site swelling

Drug interactions

• P-glycoprotein inhibitors (cyclosporine, ketoconazole, erythromycin, spinosad, amiodarone): increased ivermectin CNS penetration — neurotoxicity risk especially in MDR1-affected dogs
• Other macrocyclic lactones (selamectin, milbemycin, moxidectin, doramectin): additive or duplicative — DO NOT combine
• Spinosad: contraindicated co-administration (P-gp inhibition + GABA agonist activity)
• Benzodiazepines (diazepam): theoretical additive CNS depression
• GABAergic anaesthetics (propofol, barbiturates): additive sedation in overdose / MDR1 patients

Pregnancy and lactation

Generally safe at label doses in pregnant cattle, sheep, mares, sows, bitches. Crosses placenta in low amounts. Excreted in milk in low concentrations. Heartgard (6 µg/kg PO monthly) safe throughout pregnancy. Higher demodicosis doses (300–600 µg/kg PO q24h) should be used with caution in pregnant bitches.

Monitoring

• MDR1 genetic testing in at-risk breeds BEFORE any high-dose use (demodex, sarcoptes)
• Heartworm test BEFORE preventive use — never start in HW+ dog without staging
• Clinical response to parasite — repeat faecal at 14 days post-treatment
• Withdrawal periods (cattle): 35 d slaughter, NOT for dairy at any stage in some jurisdictions
• Watch for neuro signs (ataxia, mydriasis) — especially first 6–12 h after high dose

Toxicity and overdose

MDR1 (ABCB1) homozygous-mutant dogs (Collie, Australian Shepherd, Shetland Sheepdog, Long-haired Whippet, Old English Sheepdog, German Shepherd, McNab, English Shepherd, Silken Windhound, Border Collie): neurotoxicity at doses tolerated by other breeds. Signs: ataxia, mydriasis, hypersalivation, depression, blindness, seizures, coma, death. Onset 4–12 h after high-dose ingestion. Cats: at >0.3 mg/kg, similar neurotoxicity. Tortoises, turtles: FATAL even at low doses. Heartworm-positive dogs given microfilaricidal dose: shock-like reaction from massive microfilarial death.

Management: No specific antidote. Aggressive supportive care: IV fluids, anti-seizure (diazepam, levetiracetam), thermoregulation (often hyperthermic from seizures, then hypothermic from depression), nutritional support (NG tube for prolonged coma). IV lipid emulsion (20% intralipid 1.5 mL/kg bolus then 0.25 mL/kg/min × 30–60 min) is the most effective specific treatment — pulls lipophilic ivermectin out of the CNS. Activated charcoal q4–6h × 24 h if recent ingestion. Coma may last 1–4 weeks but recovery is possible with intensive nursing.

Clinical pearls

• Dogs: monthly heartworm prevention at 6 µg/kg (Heartgard) is the lowest, safest dose — well below the MDR1-sensitive threshold even in mutants
• Demodicosis / sarcoptic mange: 300–600 µg/kg PO q24h × weeks-months — only after MDR1 test if breed is at risk
• Cattle: 200 µg/kg SC (Ivomec) or pour-on — single dose treats GI nematodes, lungworms, lice, mange, grubs
• Sheep / goats: 200 µg/kg PO or SC — but resistance is widespread, FECRT recommended
• Horses: 200 µg/kg PO (Eqvalan paste) for most strongyles + bots — NOT effective against encysted small strongyles (use moxidectin)
• Pigs: 300 µg/kg SC for sarcoptes + ascarids + lice
• Heartworm-positive dogs: microfilaricidal use (50 µg/kg PO) only after adulticidal melarsomine — pre-treat with prednisolone to blunt shock reaction
• NEVER use injectable cattle formulation orally in dogs — concentration mismatch causes fatal overdose
• TORTOISES / TURTLES: NEVER — uniformly fatal

Mechanism of action

Macrocyclic lactone (avermectin) endectocide. Binds glutamate-gated and GABA-gated chloride channels in invertebrate nerve / muscle cells, causing prolonged chloride influx → hyperpolarisation → paralysis and death of nematodes and arthropods. Mammalian GABA receptors are in the CNS only, protected by the blood-brain barrier (BBB); ivermectin is normally a P-glycoprotein (MDR1 / ABCB1) substrate that is actively pumped out of the CNS — animals with MDR1 mutation (Collies, related breeds) lack this protection and are exquisitely sensitive to neurotoxicity.

Formulations and products

• Ivomec 1% injection (10 mg/mL) cattle/swine
• Equine oral paste 1.87% (18.7 mg/g, 6.08 g syringe — Plumb’s p.688)
• Heartgard tablet 68 µg
• Heartgard tablet 136 µg
• Heartgard tablet 272 µg
• Sheep drench 0.08% (0.8 mg/mL)
• Neomec 1 % injection 10 mg/mL (Intas, 1/10/100 mL)
• Neomec SX 10 mg/mL + Clorsulon 100 mg/mL (Intas)
• Neomec LA 31.5 mg/mL long-acting (Intas)
• Hitek injection 10 mg/mL (Virbac)
• Hitek-F injection 10 mg/mL + Clorsulon 100 mg/mL (Virbac)
• Hitek Platinum injection 31.5 mg/mL (Virbac, long-acting)
• Hitek pet injection 10 mg/mL (Virbac, 1 mL vial)
• Neomec Inj. (Intas (Neovet)) — 10 mg/mL (1 %), Injection
• Neomec SX (Intas (Neovet)) — Ivermectin 10 + Clorsulon 100 mg/mL, Combination injection (incl. liver fluke)
• Neomec LA (Intas (Neovet)) — 31.5 mg/mL (3.15 %), Long-acting injection
• Hitek (Virbac) — 10 mg/mL, Injection
• Hitek-F (Virbac) — Ivermectin 10 + Clorsulon 100 mg/mL, Combination injection
• Hitek Platinum (Virbac) — 31.5 mg/mL, Long-acting injection
• Hitek Tablet (Virbac) — Ivermectin (per tablet), Oral dewormer tablet
• Ipraz (Virbac) — Ivermectin 2 mg + Praziquantel 50 mg, Broad-spectrum tablet (dogs/cats)
• Vermact Vet (Mankind Veticura) — 10 mg/mL (1 %), SC injection
• Fendikind-Plus (Mankind Veticura) — Fenbendazole 3 g + Ivermectin 100 mg per bolus, Combination broad-spectrum bolus (fenbendazole + ivermectin)

Storage

Injectable / pour-on / paste: 15–25 °C, dry, protected from light and freezing. Discard if frozen — formulation breaks. Multidose injectable: 28 days after broaching. Heartgard chewables: 15–30 °C, dry.

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

• Fluralaner
• Halofuginone
• Imidacloprid
• Imidocarb Dipropionate
• Levamisole
• Levamisole + Oxyclozanide
• Lotilaner
• Lufenuron

Frequently asked questions