Moxidectin
Semi-synthetic methoxime derivative of nemadectin
Also known as: Cydectin · ProHeart · Advantage Multi · Quest · ComboCare · Advocate · Bravecto Plus · Endectrid · Moxiclear · Prinovox · CL-301423 · Moxidectina · Moxidectinum
Reviewed by the VetSheet Veterinary TeamUpdated Apr 5, 2026Evidence-based veterinary reference
Doses are a clinical reference for licensed veterinary professionals. Always confirm against the current label and the individual patient.
Dosing by species
🌎 NA — North America🌍 EU — Europe
Dogs
| Indication | Dose | Route | Frequency | Duration | Region |
|---|---|---|---|---|---|
| Prevention of heartworm disease, adult fleas, hookworms, roundworms, and whipworms (Advantage Multi) | 10 mg/kg imidacloprid with 2.5 mg/kg moxidectin once a month by topical administration | topical | q30d | — | 🌎 NA |
| Heartworm prevention, hookworms (ProHeart 6) | 0.05 mL of the constituted suspension/kg body weight (provides 0.17 mg moxidectin/kg) | SC | q6mo | — | 🌎 NA |
| Scabiocidal therapy | 0.25 mg/kg SC every 7 days for three treatments OR 0.4 mg/kg PO every 3-4 days for 3-6 weeks | SC/PO | q7d or q3-4d | 3-6 weeks | 🌎 NA |
| Generalized demodicosis | 0.2-0.4 mg/kg PO once a day | PO | q24h | Until parasitic cure (averages 112 days) | 🌎 NA |
| Treatment of canine sarcoptic mange | 10 mg/kg body weight imidacloprid and 2.5 mg/kg body weight moxidectin | topical | q14d | 3 occasions | 🌍 EU |
| Flea, lice, mite, nematode treatment and heartworm/angiostrongylosis prevention | 10 mg/kg body weight imidacloprid and 2.5 mg/kg body weight moxidectin | topical | monthly | Ongoing for prevention | 🌍 EU |
- Prevention of heartworm disease, adult fleas, hookworms, roundworms, and whipworms (Advantage Multi): For dogs 3-9 lb = 0.4 mL; 9.1-20 lb = 1 mL; 20.1-55 lb = 2.5 mL, 55.1-88 lb = 4 mL.
- Heartworm prevention, hookworms (ProHeart 6): Do not overdose growing puppies. Mix at least 30 minutes prior to use.
- Scabiocidal therapy: May cause toxicity in ABCB1 mutant genotype dogs.
- Generalized demodicosis: May cause toxicity in ABCB1 mutant genotype dogs.
- Treatment of canine sarcoptic mange: Apply via spot-on pipette.
- Flea, lice, mite, nematode treatment and heartworm/angiostrongylosis prevention: Frequent shampooing may reduce efficacy.
Cats
| Indication | Dose | Route | Frequency | Duration | Region |
|---|---|---|---|---|---|
| Prevention of heartworm disease, adult fleas, ear mites, hookworms, and roundworms (Advantage Multi) | 10 mg/kg imidacloprid/1 mg/kg moxidectin once a month by topical administration | topical | q30d | — | 🌎 NA |
| Feline Aelurostrongylosis (Aelurostrongylus abstrusus) | One to three topical applications of 1 mg/kg moxidectin (in combination with imidacloprid) | topical | 1-3 applications | — | 🌎 NA |
| Flea, mite, nematode treatment and heartworm prevention | 10 mg/kg body weight imidacloprid and 1.0 mg/kg body weight moxidectin | topical | monthly | Ongoing for prevention | 🌍 EU |
| Flea/tick control and heartworm/nematode prevention (Bravecto Plus) | 280 mg/ml fluralaner and 14 mg/ml moxidectin (volume based on weight) | topical | q12w for flea/tick control, q8w for heartworm prevention | Ongoing | 🌍 EU |
- Prevention of heartworm disease, adult fleas, ear mites, hookworms, and roundworms (Advantage Multi): For cats 2-5 lb = 0.23 mL; 5.1-9 lb = 0.4 mL; 9.1-18 lb = 0.8 mL.
- Flea, mite, nematode treatment and heartworm prevention: Apply via spot-on pipette. Severe effects may be seen if applied to cats with adult heartworm disease.
- Flea/tick control and heartworm/nematode prevention (Bravecto Plus): Not for use in kittens <9 weeks or cats <1.2 kg.
Horses
| Indication | Dose | Route | Frequency | Duration | Region |
|---|---|---|---|---|---|
| Gastrointestinal parasites (Oral Gel) | Dial in the weight of the animal on the syringe | PO | single dose | — | 🌎 NA |
| Mucosal stages of small strongyles | 400 micrograms/kg PO | PO | single dose | — | 🌎 NA |
- Gastrointestinal parasites (Oral Gel): Horses weighing more than 1250 lb require additional gel from a second syringe.
Cattle
| Indication | Dose | Route | Frequency | Duration | Region |
|---|---|---|---|---|---|
| Internal and external parasites (Pour-On) | 1 mL (5 mg)/10 kg (22 lb) bodyweight applied directly to the hair and skin along the top of the back | topical | single dose | — | 🌎 NA |
| Internal and external parasites (Injectable) | 0.2 mg/kg [1 mL for each 110 lb (50 kg) of bodyweight] subcutaneously | SC | single dose | — | 🌎 NA |
Sheep
| Indication | Dose | Route | Frequency | Duration | Region |
|---|---|---|---|---|---|
| Internal parasites | 0.2 mg/kg [1 mL per 11 lb (1 mL per 5 kg) bodyweight] PO (drench) | PO | single dose | — | 🌎 NA |
| Gastrointestinal helminthes in Camelids (NWC) | 0.2 mg/kg | PO | single dose | — | 🌎 NA |
- Gastrointestinal helminthes in Camelids (NWC): Regimen of choice for camelids.
Goats
| Indication | Dose | Route | Frequency | Duration | Region |
|---|---|---|---|---|---|
| Internal parasites | Twice the sheep dose (0.4 mg/kg) | PO | single dose | — | 🌎 NA |
Doses are a clinical reference for licensed veterinary professionals. Always confirm against the current label and the individual patient.
Overview
Moxidectin is a potent, second-generation macrocyclic lactone (avermectin/milbemycin subclass) antiparasitic agent used extensively in both small and large animal veterinary medicine.
Key pharmacological features include:
- Broad-Spectrum Efficacy: Effective against a wide range of internal nematodes (roundworms, hookworms, whipworms, heartworm larvae) and external arthropods (fleas, mites, lice, grubs).
- High Lipophilicity: Moxidectin is approximately 100 times more lipophilic than ivermectin. This allows for extensive tissue distribution, prolonged half-lives, and the feasibility of sustained-release formulations (e.g., 6-month injectable heartworm preventatives).
- ABCB1 (MDR1) Safety Profile: While dogs with the ABCB1-1∆ gene mutation are sensitive to macrocyclic lactones, moxidectin at standard FDA-approved labeled doses (topical and oral heartworm prevention) is generally considered safe for these breeds. However, high-dose off-label use (e.g., for demodicosis) can precipitate severe neurotoxicity.
It is available in a wide variety of formulations, including topical spot-ons (often combined with imidacloprid), sustained-release injections, oral gels, and pour-on solutions.
Mechanism of action
Moxidectin exerts its antiparasitic effects by disrupting the neurological function of invertebrates:
- Glutamate-Gated Chloride Channels (GluCl): Moxidectin binds selectively and with high affinity to GluCl channels present in invertebrate nerve and muscle cells → increases membrane permeability to chloride ions → causes cellular hyperpolarization → results in flaccid paralysis and death of the parasite.
- GABA Receptors: It also enhances the release of gamma-aminobutyric acid (GABA) at presynaptic neurons, further blocking post-synaptic stimulation.
Mammalian Safety: Mammals do not possess GluCl channels. Furthermore, the P-glycoprotein (P-gp) efflux pump at the mammalian blood-brain barrier actively prevents moxidectin from entering the central nervous system, protecting mammalian GABA receptors from exposure.
Safety & warnings
Contraindications
- Hypersensitivity to the drug
- Dogs not tested for heartworm infection prior to use
- Sick, debilitated, or underweight dogs (specifically for the 6-month injectable)
- Female dairy cattle of breeding age
- Horses intended for food purposes
- Foals younger than 4 months of age
- Kittens < 9 weeks of age
- Dogs < 7 weeks of age
- Dogs with Class 4 heartworm disease
- Cats < 1.2 kg (for fluralaner combination)
- Breeding males (for fluralaner combination)
Adverse effects
- Dogs: Lethargy, vomiting, ataxia, anorexia, diarrhea, nervousness, weakness, polydipsia, pruritus
- Dogs (Injectable): Rare but serious reports of anaphylaxis, liver disease, autoimmune hemolytic disease, convulsions
- Cats: Recumbency (rare)
- Horses: Minimal at labeled doses; CNS depression and coma reported in foals at high doses
- Cattle: Minimal to nonexistent at labeled doses
- Transient pruritus at application site
- Erythema at application site
- Hypersalivation (if licked)
- Emesis and haematemesis
- Diarrhoea
- Pyrexia
- Tachypnoea
- Mydriasis
- Severe systemic reactions in cats with adult heartworm disease
Precautions
Heartworm Testing: Always test dogs for existing heartworm infections before initiating moxidectin therapy. Adult heartworms and microfilariae should be removed prior to therapy.
- ABCB1 (MDR1) Mutants: Safe at standard labeled preventative doses. However, off-label high doses (e.g., for demodicosis or scabies) can cause severe neurotoxicity in herding breeds with this mutation.
- Body Condition: Animals with very low body fat (neonates, cachexia) may experience significantly higher serum levels due to the drug's extreme lipophilicity, making them more prone to adverse reactions.
- Vaccinations: Caution is advised when administering the 6-month sustained-release injection concurrently with vaccinations, as anaphylaxis has been reported.
Drug interactions
Effects may be potentiated by moxidectin; concurrent use is generally not advised.
May inhibit the efflux pump at the blood-brain barrier, potentially increasing the risk of moxidectin neurotoxicity, especially in dogs with the ABCB1-1∆ mutation.
Increased risk of neurological toxicity due to competitive inhibition at the blood-brain barrier
Additive toxicity and increased risk of adverse neurological effects
Monitoring
- Heartworm status prior to initiation of therapy
- Fecal egg count reduction testing (FECRT) in horses (target >95% reduction to monitor for resistance)
- Signs of neurotoxicity, especially in herding breeds or animals with low body fat
- Heartworm status (antigen/microfilariae testing) prior to initiating preventative therapy
- Resolution of clinical signs of parasitic infection
- Application site for erythema or pruritus
Pharmacokinetics
Half-life
Absorption
Highly lipophilic (100 times that of ivermectin).
Distribution
Volumes of distribution are very high due to extreme lipophilicity. Animals with very low body fat (neonates, cachexia) may have significantly higher serum levels than normal patients.
Metabolism
Hepatic metabolism (inferred from macrocyclic lactone class properties).
Elimination
Long duration of plasma residence (14-15 days in cattle). After SC injection in cows, approximately 5% of the dose can be passed to the suckling calf.
Overdose
Moxidectin generally has a wide margin of safety when administered at labeled doses.
- Dogs: Dosages up to 300X (1120 mcg/kg) demonstrated little to no effects in normal dogs. However, in dogs with the ABCB1 (MDR1) mutant genotype, toxicity can be seen at doses as low as 90 mcg/kg.
- Clinical Signs of Toxicity: Dysorexia, hypersalivation, mydriasis, fasciculations, ataxia, tremors, seizures, vomiting, hyperesthesia, and recumbency/coma.
- Treatment: Supportive care. Intravenous fat emulsion (IVFE) has been successfully used to treat toxicity associated with macrocyclic lactones due to their highly lipid-soluble nature.
Available products
Formulations
- Sustained-release injection (microspheres)
- Topical solution (spot-on)
- Pour-on solution
- Injectable solution
- Oral drench
- Oral gel
- Topical spot-on: 10 mg/kg imidacloprid + 1.0 mg/kg moxidectin (Cats)
- Topical spot-on: 10 mg/kg imidacloprid + 2.5 mg/kg moxidectin (Dogs)
- Topical spot-on: 280 mg/ml fluralaner + 14 mg/ml moxidectin (Cats - Bravecto Plus)
Veterinary
- ProHeart 6: 10% Sustained-Release Injectable (598 mg/vial)
- Cydectin Pour-On for Cattle: 0.5% (5 mg/mL)
- Cydectin Injectable Solution: 10 mg/mL
- Cydectin Oral Drench for Sheep: 1 mg/mL
- Quest Oral Gel: 20 mg/mL
- Quest Plus Oral Gel: 20 mg/mL moxidectin + 125 mg/mL praziquantel
- Advantage Multi for Cats: 10 mg/mL moxidectin + 100 mg/mL imidacloprid
- Advantage Multi for Dogs: 25 mg/mL moxidectin + 100 mg/mL imidacloprid
- Advocate spot-on solution
- Bravecto Plus spot-on solution
- Endectrid spot-on solution
- Moxiclear spot-on solution
- Prinovox spot-on solution
Regulatory status
Withdrawal times: cattle meat 14-65 days depending on formulation
POM-V classification.
POM-V classification.
No regulatory data for: 🇺🇸 US · 🇭🇰 HK · 🇹🇼 TW · 🇯🇵 JP · 🇰🇷 KR · 🇦🇺 AU
Storage & stability
ProHeart 6: Store unconstituted product at or below 25°C (77°F) and protect from light. Once constituted, stable for 4 weeks under refrigeration at 2°-8°C (36°-46°F). Cydectin injection/drench: Store at or below 25°C (77°F) and protect from light. Cydectin Pour-on: Store at or below room temperature; do not freeze. Quest gel: Store at room temperature (59°F-86°F); avoid freezing.
Client information
- Heartworm Testing: Your pet must be tested for heartworms before starting this medication. Giving this drug to a heartworm-positive pet can cause severe reactions.
- Application: If using the topical spot-on, apply it directly to the skin (part the hair) at the base of the neck/shoulder blades where the pet cannot lick it off. Keep treated pets separated from each other and children for a few hours until the application site is dry.
- Side Effects: Watch for signs of lethargy, vomiting, stumbling (ataxia), or excessive drooling. Contact your veterinarian immediately if you notice any neurological signs.
- ProHeart 6: If your dog receives the 6-month injection, ensure you read the Client Information Sheet provided by your veterinarian and monitor for any signs of allergic reaction (facial swelling, hives, severe lethargy) in the days following the injection.
VetSheet drug reference is intended for licensed veterinary professionals as a clinical decision-support aid, not a substitute for professional judgement or the manufacturer’s current label.