What is moxidectin injectable?
Moxidectin injectable (ProHeart 6®, ProHeart 12®) is used in dogs to prevent heartworm disease and treat existing hookworm infections. It is convenient for pet owners because an injection provides protection for several months. ProHeart 6® provides 6 months of heartworm prevention, and ProHeart 12® provides 12 months of heartworm prevention.
How is moxidectin injectable given?
- Moxidectin injectable comes as an injectable medication which must be given by your veterinarian or a trained veterinary staff member.
- ProHeart 6® is given every 6 months and ProHeart 12® is given every 12 months.
This medication should start having effects within 1 to 2 days, but you may not see the effects of this medication outwardly.
What if I miss giving my pet the medication?
If you miss an application, contact your veterinarian as soon as possible to schedule the next dose. Additional testing may be needed to ensure that a heartworm infection did not occur if there was a gap in coverage.
Are there any potential side effects?
Moxidectin injectable may cause the following side effects:
- Redness, itching, or irritation at the injection site
- Mild vomiting or diarrhea
- Excessive salivation
- Low energy
Serious adverse reactions associated with this drug may occur without warning and could, in rare cases, lead to death. If any of the following signs develop, stop giving moxidectin injectable and contact your veterinarian immediately:
- Difficulty breathing or collapse (may indicate anaphylaxis – a life-threatening allergic reaction)
- Facial swelling, itching, or hives (may indicate an allergic reaction)
- Pale gums
- Fever
- Increased thirst or urination
- Bleeding or bruising
- Loss of appetite
- Weight loss
- Seizures
- Significant or bloody vomiting or diarrhea
Drug sensitivities can develop over time, with repeated exposure. Your pet may have no reaction after the first few doses but may develop a sensitivity later. It is important to watch for signs of an allergic reaction over the entire course of treatment and notify your veterinarian if you have any concerns.
Other side effects may occur. If you notice anything unusual, contact your veterinarian immediately. This long-acting medication will stop working after several months. The duration of effect depends on the type of medication used (6-month or 12-month ProHeart®).
Are there any risk factors for this medication?
DO NOT USE moxidectin injectable in:
- Pets that are allergic to moxidectin
- Pets that are sick, frail, or underweight
- Pets that are less than 6 months old for ProHeart® 6 or less than 12 months old for ProHeart® 12
USE WITH CAUTION in:
- Pets with pre-existing allergic disease, including food allergy and allergy dermatitis
- Pets that are receiving vaccinations during the same visit
- Pets that are heartworm-positive
- Pets with kidney or liver disease
- Pets that are receiving certain other medications
- Pets that are pregnant, nursing, or used for breeding
Are there any drug interactions I should be aware of?
Several medications should be used with caution when given with moxidectin injectable, including:
- Amiodarone
- Benzodiazepines
- Carvedilol
- Clarithromycin or erythromycin
- Cyclosporine (Atopica®)
- Itraconazole or ketoconazole
- Spinosad (Comfortis®)
- Spironolactone
- Tamoxifen
- Verapamil or diltiazem
In dogs with the MDR1 mutation, which affects the transport of certain drugs, use increased caution when administering injectable moxidectin with the drugs listed above.
Is any monitoring needed with this medication?
- Dogs should be tested for heartworm disease before being treated with moxidectin injectable. If your dog tests positive for adult heartworms, your veterinarian should treat the infection with appropriate medication before administering moxidectin injectable.
- At home, monitor for any side effects such as those noted above. If any side effects occur, discontinue the medication, and contact your veterinarian.
- Your veterinarian will let you know when they want to reassess your pet to ensure the medication is working and not causing side effects.
How do I store moxidectin injectable?
This medication is administered by your veterinarian, so you will not need to store this medication at home.
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. Be prepared to provide information about the product and your pet's weight and symptoms. Report any adverse effects to the FDA or Health Canada.
© Copyright 2026 LifeLearn Inc. This content was written by LifeLearn Animal Health (LifeLearn Inc.) and is licensed to this practice for the personal use of its clients. Copying, printing, or further distributing this material is prohibited without LifeLearn’s express written consent. The use of artificial intelligence or automated tools to rewrite, republish, adapt, or repurpose this content, in whole or in part, is prohibited and does not create any ownership or derivative rights. This content does not contain all available information about medications and has not been reviewed by the FDA’s Center for Veterinary Medicine or Health Canada’s Veterinary Drugs Directorate. This content is not a substitute for medical advice or a proper clinical examination. Please contact your veterinarian if you have any questions or concerns about your pet’s health. Last updated on Sep 25, 2026. |