Moxidectin Topical

By Rania Gollakner, BS, DVM, MPH

What is moxidectin?

Moxidectin topical (brand names: Advantage Multi®, Advocate®, ProHeart®) is a topical avermectin antiparasitic that is used to prevent heartworms and treat intestinal parasites (hookworms, roundworms, and whipworms), and is combined with imidacloprid to also treat fleas. It is also approved for treating sarcoptic mange and to treat circulating heartworm microfilaria (immature heartworms) in dogs. In cats, it may also be used to treat ear mites.

Its use in dogs to treat adult heartworm in combination with doxycycline is ‘off label’ or ‘extra label’. Many drugs are commonly prescribed for off label use in veterinary medicine. In these instances, follow your veterinarian’s directions and cautions very carefully as their directions may be significantly different from those on the label.

How quickly does it work?

Moxidectin will start working in about 24 hours to kill ticks and intestinal parasites. Imidacloprid, the medication paired with topical moxidectin, begins to kill fleas within 4 hours.

How is moxidectin given?

Moxidectin is applied topically to the skin. During the first 30 minutes after application, monitor to ensure that your dog does not lick the product. Do not apply this medication to irritated skin. Do not bathe your pet for at least 4 days after its application.

What if I miss giving my pet the medication or my shipment is late?

Give the dose as soon as you remember and start a new monthly dosing schedule. For example, if you forgot to give your pet his/her dose on June 1st and remember on June 18th, give the dose on June 18th and start a new monthly schedule. The next dose your pet will receive would be on July 18th. Do not give your pet two doses at once. Contact your veterinarian if you are concerned about a missed dose.

Are there any potential side effects?

When used as directed in dogs, side effects are uncommon. If the product is eaten, side effects include depression, salivation, dilated pupils, incoordination, panting, and generalized muscle tremors. In dogs that are sensitive to milbemycin, coma and death are possible.  

In cats, behavioral changes such as agitation, excessive grooming, hiding, pacing, and spinning may occur. Other side effects may include scratching, application site reactions, rubbing, lethargy, hyperactivity, uncoordinated walking, trembling, excessive salivation, increased drinking, and coughing or gagging. If ingested, increased salivation, tremors, vomiting, and decreased appetite can occur.

This long-acting medication is designed to last for at least 4 weeks. However, negative side effects are usually short lived if they occur at all. In dogs, even when the medication is accidentally ingested, side effects should not last more than 24 hours in a healthy animal.

Are there any risk factors for this medication?

Moxidectin should not be used in pets that are hypersensitive or allergic to it. Some breeds of dogs (e.g., collies, sheepdogs, and collie- or sheepdog-cross breeds) are more sensitive to moxidectin than others. This is typically due to a specific genetic mutation (MDR1) that makes them less able to tolerate high doses of moxidectin. If used at prescribed doses for heartworm prevention, it is considered safe for MDR1 affected dogs. Use cautiously in animals with low body fat (sick or very young) as they are more prone to side effects.

Do not use this medication in sick, debilitated, or underweight cats.

Safety in breeding, pregnant, or nursing animals has not been established, however, there has been no evidence to date of adverse effects in these animals.

Are there any drug interactions I should be aware of?

Specific interactions with moxidectin have not been reported, however, benzodiazepines should be closely monitored when used with moxidectin.

In dogs with MDR1 genetic mutations, the following medications should not be used or should be used with caution with moxidectin: amiodarone, carvedilol, clarithromycin, cyclosporine, diltiazem, erythromycin, itraconazole, ketoconazole, quinidine, spinosad, spironolactone, tamoxifen, verapamil.

Be sure to tell your veterinarian about any medications (including vitamins, supplements, or herbal therapies) that your pet is taking.

Is there any monitoring that needs to be done with this medication?

There is no specific monitoring that needs to be done while your pet is taking this medication. Your veterinarian may monitor your pet to be sure that the medication is working.

How do I store moxidectin topical?

Moxidectin topical should be stored between 4°C – 25°C (39°F – 77°F).

What should I do in case of emergency?

If you suspect an overdose or an adverse reaction to the medication, call your veterinary office immediately. If they are not available, follow their directions in contacting an emergency facility.

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