Moxidectin
Moxidectin is a milbemycin macrocyclic lactone with prolonged, formulation-dependent antiparasitic activity. Veterinary applications include heartworm prevention, selected intestinal and lung nematodes, and some ectoparasites. It is used in companion animals, horses and livestock. Conventional, topical and sustained-release products differ substantially in their clinical duration and parasite coverage.
Group
Macrocyclic lactone antiparasitic
Mechanism of Action
Moxidectin activates parasite glutamate-gated chloride channels, increasing chloride entry and hyperpolarizing susceptible nerve and muscle cells. Impaired excitability produces paralysis and disruption of feeding, leading to parasite death. Its lipophilicity and formulation-dependent release prolong exposure. Developing heartworm larvae, susceptible intestinal nematodes and selected mites are affected according to their sensitivity and life stage.
Dose Rates
Dogs
| Use / stage | Dose | Route | Schedule | Instructions |
|---|---|---|---|---|
| Heartworm prevention oral | 3 mcg/kg | PO | Every 720 h | Every 30 days; not the Simparica Trio component dose. |
| Heartworm prevention topical | 2.5 mg/kg | TOPICAL | Every 720 h | Monthly canine topical product only; avoid licking. Use only the specified small-animal topical product; cattle pour-on is unsuitable. |
| Heartworm prevention six-month injection | Reference only | SC | ProHeart 6: 0.17 mg/kg, corresponding to 0.05 mL/kg of 3.4 mg/mL constituted suspension every 6 months. Maximum 3 mL per injection site. Do not interchange the dose to this exact depot product. | |
| Heartworm prevention twelve-month injection | Reference only | SC | ProHeart 12: 0.5 mg/kg, corresponding to 0.05 mL/kg of 10 mg/mL constituted suspension every 12 months. This is not interchangeable with the six-month product. | |
| Sarcoptic mange | 200–250 mcg/kg | PO, SC | Every 168 h | Up to 42 days; Do not use in: Macrocyclic-lactone sensitivity; Course 3-6 weeks. |
| Demodicosis | 200 mcg/kg | SC | Every 168–336 h | One to four treatments, until parasitological response; exact repeat count is to be tracked explicitly. |
| Demodicosis | 400 mcg/kg | PO | Every 24 h | Do not use in: Macrocyclic-lactone sensitivity |
| Refractory demodicosis | 500 mcg/kg | PO | Every 24 h | Up to 161 days; Do not use in: Macrocyclic-lactone sensitivity; Reported course 21-23 weeks; continue according to skin scrapings. |
| Refractory demodicosis | 0.5–1 mg/kg | SC | Every 72 h | Up to 154 days; Reported course 21-22 weeks; use only an appropriate non-depot injection, never ProHeart sustained-release products. |
| Combined sarolaner-moxidectin-pyrantel prevention | Reference only | PO | Simparica Trio minimum component exposures are sarolaner 1.2 mg/kg, moxidectin 24 mcg/kg and pyrantel 5 mg/kg monthly. Exact whole-chew selection requires the verified product weight-band table. | |
| Sarcoptic mange | 0.4 mg/kg | PO | Every 72–96 h | Up to 42 days; Do not use in: ABCB1-associated macrocyclic-lactone sensitivity; Separate 3-6-week oral alternative; exclude macrocyclic-lactone sensitivity. |
| Demodicosis | 0.2–0.4 mg/kg | PO | Every 24 h | Do not use in: ABCB1-associated macrocyclic-lactone sensitivity; Treat to clinical and parasitological endpoints, not a fixed arbitrary number of days. |
Cats
| Use / stage | Dose | Route | Schedule | Instructions |
|---|---|---|---|---|
| Heartworm prevention topical | 1 mg/kg | TOPICAL | Every 720 h | Feline 1% moxidectin combination only; do not use canine 2.5% solution. Use only the specified small-animal topical product; cattle pour-on is unsuitable. |
| Combined fluralaner-moxidectin prevention | Reference only | TOPICAL | Bravecto Plus delivers fluralaner 40 mg/kg plus moxidectin 2 mg/kg every 2 months. This is a product-specific combination, not a moxidectin-only preparation. | |
| Aelurostrongylus abstrusus treatment | Reference only | TOPICAL | Moxidectin 1 mg/kg as the specific imidacloprid combination, one to three applications; repeat timing is not specified and must not be guessed. |
Horses
| Use / stage | Dose | Route | Schedule | Instructions |
|---|---|---|---|---|
| Gastrointestinal parasites | 0.4 mg/kg | PO | Once | Do not use in: Foals younger than 6 months, Small ponies, Debilitated animals |
Cattle
| Use / stage | Dose | Route | Schedule | Instructions |
|---|---|---|---|---|
| Nematodes and ectoparasites | 0.2 mg/kg | SC | Once | Conventional cattle injection; not canine depot injection. |
| Nematodes and ectoparasites | 0.5 mg/kg | TOPICAL | Once | 5 mg/mL cattle pour-on, applied along the midline from withers to tail head. |
Sheep
| Use / stage | Dose | Route | Schedule | Instructions |
|---|---|---|---|---|
| Gastrointestinal nematodes | 0.2 mg/kg | PO | Once | 1 mg/mL oral drench; 1 mL/5 kg. |
Goats
| Use / stage | Dose | Route | Schedule | Instructions |
|---|---|---|---|---|
| Gastrointestinal nematodes | 0.4 mg/kg | PO | Once | Twice the specified sheep oral dose in the provided camelid/small-ruminant guidance; assess parasite susceptibility. |
Llamas
| Use / stage | Dose | Route | Schedule | Instructions |
|---|---|---|---|---|
| Gastrointestinal helminths | 0.2 mg/kg | PO | Once |
Alpacas
| Use / stage | Dose | Route | Schedule | Instructions |
|---|---|---|---|---|
| Gastrointestinal helminths | 0.2 mg/kg | PO | Once |
Indications
- Prevention of heartworm disease in dogs and cats using a corresponding species-specific product.
- Treatment and control of selected intestinal nematodes in companion animals or livestock.
- Treatment of selected canine lungworm infections with an indicated or supported regimen.
- Treatment of selected demodectic, sarcoptic or ear-mite infestations with an appropriate product or extra-label protocol.
- Control of susceptible equine strongyles, including supported encysted small-strongyle stages, and selected other equine parasites.
- Broad parasite control with moxidectin-containing combinations, with flea, tick or tapeworm coverage supplied by the relevant companion ingredients.
Contraindications
- High-dose use in ABCB1-sensitive animals requires particular caution.
- Dogs younger than 2 months for the described general protocols
Interactions
- P-glycoprotein inhibitors, including azole antifungals and cyclosporine, can increase central nervous system exposure.
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 |
|---|---|---|---|
| Moxidectin 20 mg/mL equine oral gel | Oral Gel | 20 mg / mL | PO |
| Moxidectin 5 mg/mL cattle pour-on | Other | 5 mg / mL | TOPICAL |
| Moxidectin 1 mg/mL sheep drench | Oral Liquid | 1 mg / mL | PO |
| Moxidectin conventional cattle injection 10 mg/mL injection Conventional cattle formulation; do not use for canine depot regimens. | Injection | 10 mg / mL | SC |
| Bravecto Plus topical solution Combination product; component conversion not enabled. | Other | moxidectin 14 mg / mL + fluralaner 280 mg / mL | TOPICAL |
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.
Do not use canine 2.5% topical solution in cats or livestock pour-on in small animals. Avoid oral licking of topical sites.
Avoid treatment in foals younger than 6 months, small ponies or debilitated horses under the described equine regimen.
ProHeart 6 and ProHeart 12 require their own supplied vehicles and reconstitution instructions. The 12-month preparation is described as ready for injection 30 minutes after mixing; do not interchange the products.
General canine endoparasite amount 25-300 mcg/kg is listed without route or frequency. No numeric route-specific regimen is inferred.
ProHeart 6 constituted suspension 3.4 mg/mL: 3.4 mg per 1 mL. Product-specific six-month microsphere suspension; 3 mL maximum per site.
ProHeart 12 constituted suspension 10 mg/mL: 10 mg per 1 mL. Product-specific twelve-month microsphere suspension; use supplied vehicle only.
For ProHeart 6, mix at least 30 minutes before use and gently resuspend before each withdrawal. Use 0.05 mL/kg of the exact constituted product, promptly inject SC in the dorsum of the neck and limit each site to 3 mL. Do not dose growing puppies for anticipated adult weight. The described constituted product is refrigerated at 2-8°C for up to 4 weeks; current product instructions govern its actual use period.
Advantage Multi minimum component exposures are imidacloprid 10 mg/kg plus moxidectin 2.5 mg/kg in dogs, or imidacloprid 10 mg/kg plus moxidectin 1 mg/kg in cats. The dog product is not 25% imidacloprid. Keep dog/cat pipettes and concentrations distinct; prevent licking and do not substitute cattle pour-on. The printed oral-prevention “3 mg/kg/month” conflicts with the correctly stated 3 mcg/kg/month and is not used.