Ivermectin

Ivermectin is an avermectin macrocyclic lactone used against many nematodes and arthropod parasites. Its veterinary applications span livestock deworming, equine parasite control, selected mite infestations and heartworm prevention with specific small-animal products. Parasite spectrum and duration depend on species, formulation, life stage and exposure.

Group

Macrocyclic lactone antiparasitic

Mechanism of Action

Ivermectin activates parasite glutamate-gated chloride channels, increasing chloride permeability in nerve and muscle cells. Hyperpolarization reduces excitability, causing impaired feeding, paralysis and eventual parasite death. This mechanism underlies activity against susceptible nematodes and arthropods. In heartworm prevention, exposure targets susceptible developing larval stages before they mature into adult worms.

Dose Rates

Dogs

Use / stage	Dose	Route	Schedule	Instructions
Heartworm prevention	6 mcg/kg	PO	Every 720 h	Administer every 30 days.
Ectoparasite treatment	200–400 mcg/kg	IM, SC, PO		Schedule depends on the diagnosed parasite; no repeat interval is supplied for this general regimen.
Demodicosis	Reference only	PO		Begin at 100 mcg/kg/day and increase by 100 mcg/kg/day to 600 mcg/kg/day; typical courses 60-120 days, with duration determined by skin scrapings. This escalation must not be flattened into a freely selectable range.
Sarcoptic mange and cheyletiellosis	200–400 mcg/kg	PO	Every 168 h	Up to 42 days; Do not use in: ABCB1-associated macrocyclic-lactone sensitivity; Course 4-6 weeks.
Sarcoptic mange and cheyletiellosis	200–400 mcg/kg	SC	Every 336 h	Up to 42 days; Do not use in: ABCB1-associated macrocyclic-lactone sensitivity; Course 4-6 weeks.
Heartworm prevention	6–12 mcg/kg	PO	Every 720 h
Capillaria or Eucoleus lungworm	0.2 mg/kg	PO	Once
Oslerus osleri infection	0.4 mg/kg	SC	Once
Nasal-mite infection	0.2 mg/kg	SC	Once
Scabies	300–400 mcg/kg	PO, SC	Every 168 h	Do not use in: ABCB1-associated macrocyclic-lactone sensitivity

Cats

Use / stage	Dose	Route	Schedule	Instructions
Heartworm prevention	24 mcg/kg	PO	Every 720 h	Every 30 days.
Ectoparasite treatment	200–400 mcg/kg	IM, SC, PO	Every 168 h	Repeat only according to skin scrapings and clinical response; young kittens have increased toxicity risk.
Endoparasite treatment	200–400 mcg/kg	SC, PO	Every 168 h
Ear mites	Reference only	TOPICAL	Once	Per ear: 0.5 mL of 0.1 mg/mL feline ear product (50 mcg). Local ear administration must not convert through livestock pour-on or injectable preparations.
Aelurostrongylus abstrusus infection	0.4 mg/kg	SC	Once

Horses

Use / stage	Dose	Route	Schedule	Instructions
Nematode and bot control	200 mcg/kg	PO, IM	Once	Use the corresponding formulation as part of a parasite-control programme; oral solution example is 1 mL/50 kg at 10 mg/mL.
Lice or mange	0.2 mg/kg	PO	Every 96 h

Cattle

Use / stage	Dose	Route	Schedule	Instructions
Slow-release parasite control	Reference only	PO		Calves: 5.7-13.8 mg/kg as a single slow-release bolus, designed for 135 days. This is not an immediate-release dose.
Nematode and ectoparasite control	200 mcg/kg	SC	Once
Nematode and ectoparasite control	0.5 mg/kg	TOPICAL	Once	Pour-on formulation, 5 mg/mL; 1 mL/10 kg.

Goats

Use / stage	Dose	Route	Schedule	Instructions
Nematode and ectoparasite control	200 mcg/kg	SC	Once
Nematode and ectoparasite control	0.5 mg/kg	TOPICAL	Once	Pour-on formulation, 5 mg/mL; 1 mL/10 kg.
Meningeal-worm combination	Reference only	SC		Ivermectin 0.3 mg/kg daily plus fenbendazole 50 mg/kg PO daily for 5 days to limit further Parelaphostrongylus migration. Camelids may need gastric-ulcer protection; this is not single-drug treatment.

Sheep

Use / stage	Dose	Route	Schedule	Instructions
Nematode and ectoparasite control	200 mcg/kg	SC	Once
Nematode control	200 mcg/kg	PO	Once
Meningeal-worm combination	Reference only	SC		Ivermectin 0.3 mg/kg daily plus fenbendazole 50 mg/kg PO daily for 5 days to limit further Parelaphostrongylus migration. Camelids may need gastric-ulcer protection; this is not single-drug treatment.

Pigs

Use / stage	Dose	Route	Schedule	Instructions
Nematode and ectoparasite control	300 mcg/kg	SC	Once	Inject in the neck.
Potbellied-pig ectoparasites	300 mcg/kg	SC, IM	Every 240–336 h	One dose for endoparasites; a repeat 10-14 days later for ectoparasites. The IM alternative conflicts with cattle/swine product SC-only instructions; use formulation-specific assessment.

Ferrets

Use / stage	Dose	Route	Schedule	Instructions
Heartworm prevention	0.02 mg/kg	PO	Every 720 h
Historical slow heartworm-treatment protocol	Reference only	PO		50 mcg/ferret monthly is described as a very slow treatment approach, not a proven replacement for an individualized heartworm plan.

Rabbits

Use / stage	Dose	Route	Schedule	Instructions
Sarcoptoid mites	0.3–0.4 mg/kg	SC	Every 336 h	Two treatments 14 days apart; clean and disinfect housing.
Ear mites	0.2–0.44 mg/kg	PO, SC	Every 192–432 h	Repeat once after 8-18 days; 0.2 mg/kg SC with a 14-day repeat is another specific alternative.

Mice

Use / stage	Dose	Route	Schedule	Instructions
Mites	200 mcg/kg	SC, PO	Every 168 h	Up to 21 days; Treat colony contacts and disinfect housing.

Rats

Use / stage	Dose	Route	Schedule	Instructions
Mites	200 mcg/kg	SC, PO	Every 168 h	Up to 21 days; Treat colony contacts and disinfect housing.

Gerbils

Use / stage	Dose	Route	Schedule	Instructions
Mites	200 mcg/kg	SC, PO	Every 168 h	Up to 21 days; Treat colony contacts and disinfect housing.

Guinea pigs

Use / stage	Dose	Route	Schedule	Instructions
Mites	200 mcg/kg	SC, PO	Every 168 h	Up to 21 days; Treat colony contacts and disinfect housing.
Trixacarus caviae	500 mcg/kg	SC	Every 336 h	Up to 28 days; Three treatments on days 0, 14 and 28.

Chinchillas

Use / stage	Dose	Route	Schedule	Instructions
Mites	200 mcg/kg	SC, PO	Every 168 h	Up to 21 days; Treat colony contacts and disinfect housing.

Hamsters

Use / stage	Dose	Route	Schedule	Instructions
Mites	200–500 mcg/kg	SC, PO	Every 336 h	Up to 21 days

Llamas

Use / stage	Dose	Route	Schedule	Instructions
Gastrointestinal helminths	0.2 mg/kg	PO, SC	Once
Meningeal-worm combination	Reference only	SC		Ivermectin 0.3 mg/kg daily plus fenbendazole 50 mg/kg PO daily for 5 days to limit further Parelaphostrongylus migration. Camelids may need gastric-ulcer protection; this is not single-drug treatment.

Alpacas

Use / stage	Dose	Route	Schedule	Instructions
Gastrointestinal helminths	0.2 mg/kg	PO, SC	Once
Meningeal-worm combination	Reference only	SC		Ivermectin 0.3 mg/kg daily plus fenbendazole 50 mg/kg PO daily for 5 days to limit further Parelaphostrongylus migration. Camelids may need gastric-ulcer protection; this is not single-drug treatment.

Birds

Use / stage	Dose	Route	Schedule	Instructions
Nematodes or mites	200 mcg/kg	IM, PO	Every 240–336 h	Repeat once after 10-14 days; prepare a verified dilution immediately before dosing. Species-specific tolerance is required.
Nematodes or mites	220 mcg/kg	IM		General avian alternative; dilution concentration must be verified.
Nematodes or mites	200 mcg/kg	SC
Ratite nematodes	200 mcg/kg	PO, IM, SC

Reptiles

Use / stage	Dose	Route	Schedule	Instructions
Nematodes or ectoparasites	0.2 mg/kg	PO, IM, SC	Every 336 h	Do not use in: Chelonians, Indigo snakes, Skinks; Lizards, snakes and alligators: initial dose and one repeat in 2 weeks; a third only if still positive.

Indications

Treatment and control of susceptible gastrointestinal nematodes, lungworms and selected ectoparasites in cattle, sheep, goats or pigs with an appropriate veterinary product.
Treatment and control of susceptible equine strongyles, pinworms, ascarids, bots and selected other parasites.
Prevention of heartworm disease in dogs and cats with a corresponding species-specific product.
Extra-label treatment of selected mange or mite infestations in veterinary patients, including some demodectic, sarcoptic, notoedric or ear-mite cases.
Treatment of selected other susceptible nematode or arthropod infestations in exotic veterinary species.

Contraindications

High-dose use in ABCB1-sensitive animals requires particular caution.
Animals younger than 6 weeks
Do not administer intravenously.
Chelonians, indigo snakes and skinks: ivermectin toxicity can be severe. High-dose canine protocols should exclude ABCB1-mutant dogs.

Interactions

P-glycoprotein inhibitors, including azole antifungals and cyclosporine, can increase central nervous system exposure.
Spinosad can potentiate high-dose ivermectin toxicity.

Adverse effects

Hypersalivation, ataxia, visual disturbance and central depression
Severe overdose may cause coma or death

Toxicity

Stop exposure and provide respiratory and neurologic support. Prevent further absorption when appropriate; lipid-emulsion treatment may be considered in severe lipophilic-drug intoxication.

Preparations

Preparation	Form	Strength	Route
Ivermectin 10 mg/mL injection	Injection	10 mg / mL	SC
Ivermectin 20 mg/mL injection	Injection	20 mg / mL	SC
Ivermectin 2.7 mg/mL injection	Injection	2.7 mg / mL	SC
Ivermectin 10 mg/mL oral solution	Oral Liquid	10 mg / mL	PO
Ivermectin 5 mg/mL cattle pour-on	Other	5 mg / mL	TOPICAL
Ivermectin 0.8 mg/mL sheep drench	Oral Liquid	0.8 mg / mL	PO
Ivermectin 0.1 mg/mL feline ear preparation	Other	0.1 mg / mL	TOPICAL
Ivermectin 68 mcg tablet	Tablet	68 mcg / tablet	PO
Ivermectin 136 mcg tablet	Tablet	136 mcg / tablet	PO
Ivermectin 272 mcg tablet	Tablet	272 mcg / tablet	PO
Rapimec 10 mg tablet Pondchy Pharmaceuticals Do not confuse this high-strength tablet with microgram-strength heartworm-prevention tablets.	Tablet	10 mg / tablet	PO
Neomec 10 mg tablet Do not confuse with microgram-strength heartworm-prevention tablets.	Tablet	10 mg / tablet	PO
Ivermectin 18.7 mg/g equine paste	Paste	18.7 mg / g	PO
Ivermectin 55 mcg feline tablet	Tablet	55 mcg / tablet	PO
Ivermectin 165 mcg feline tablet	Tablet	165 mcg / tablet	PO

Monitoring and Administration

Establish heartworm status before preventive treatment and use fecal examinations or skin scrapings to assess other parasite responses.

Protect from light. Do not substitute concentrated livestock products for small-animal products without exact concentration and formulation assessment.

Kittens can be highly sensitive; neurotoxicity and death have occurred at 0.3-0.4 mg/kg in reported young cats.

For high-dose canine treatment, reported escalation approaches begin at 50-100 mcg/kg and increase by 50-100 mcg/kg/day while observing for neurotoxicity. Continue demodicosis treatment until 4 weeks after the second consecutive negative monthly skin scraping.

A preventative heartworm dose may precede adulticide treatment for 2-3 months. The described combined programme adds doxycycline 10 mg/kg PO daily for 28 days; it is not a substitute for a complete adulticide plan.

Published withdrawal figures in the reported guidance are formulation- and jurisdiction-specific; the goat injection meat figure of 35 hours is inconsistent with surrounding guidance and must not be used as a withdrawal instruction.

Alternative canine Demodex escalation increases 100 mcg/kg every third day until 600 mcg/kg/day, then treats 1-2 months beyond two negative scrapings. Another starts 50 mcg/kg, then 120 mcg/kg for a week, 200 mcg/kg for 3 days and increments 100 mcg/kg weekly. Keep these schedules separate; stop immediately for neurotoxicity. A doxycycline/ivermectin-pyrantel slow-kill study used doxycycline 10 mg/kg/day for 30 days and ivermectin 6-14 mcg/kg every 15 days for 6 months; clearance was incomplete and this is not a general adulticide recommendation.

For cattle SC injection, divide volumes greater than 10 mL between sites. The printed 200 mg/kg cattle IM instruction conflicts by 1000-fold with the repeated 200 mcg/kg dose and must not be used. Fixed Amazon/macaw doses lack sufficiently specific patient weights, and a finch amount lacks a route; no universal fixed-bird regimen is derived.