If you’re looking for liquid heartworm medicine for dogs, you probably know that heartworms are a parasite in dogs that are spread by mosquitos. Dogs in many areas of the United States have a high infection rate with heartworms unless they are treated with heartworm prevention medications. 

Heartworm preventive medication has traditionally come in a flavored chewable pill form. That’s great unless you have one of the few dogs who think the chewable heartworm pills are yucky. That leaves dog owners trying to figure out how to protect their dogs without forcing a pill down their 

Unfortunately, there is no commercially available liquid heartworm preventive that you can give your dog by mouth. The liquid heartworm medicine for dogs sold in the U.S. is all made for topical application or injection only. 

The topical and injectable heartworm products can still be a good option for dogs who won’t take heartworm pills. 


  • Liquid ORAL heartworm prevention medicine is not available for dogs in the U.S. right now.
  • There are several good alternatives from injections to topicals for dogs who won’t eat chewable heartworm prevention pills.
  • Your veterinarian can recommend the best option that will keep your dog happy and protected from parasites.

Topical Liquid Heartworm Medicine for Dogs 

Topical liquid heartworm prevention is a good alternative if your dog won’t take it as a chewable or pill. All you have to do is apply it to their skin.

These products are packaged as a few milliliters of clear liquid in a small tube. The top of the tube is pierced and the dog owner applies the liquid to their dog’s skin in the area between the shoulder blades at the base of the neck. The liquid is absorbed into the bloodstream through the skin. These products are effective for one month before a new application is required. 

Advantage Multi®

Liquid for topical use only. Contains imidacloprid and moxidectin to prevent fleas, intestinal worms and heartworm infestation. (1)


Liquid for topical use only. The active ingredient is moxidectin. Used to prevent heartworm and intestinal parasite infestation in dogs. (2)

Revolution Plus®

Liquid for topical use only. Active ingredient is selamectin and sarolaner. It is used in dogs to prevent fleas, some ticks, intestinal parasites and heartworms. (7)

Injectable Liquid Heartworm Medicine for Dogs


Moxidectin is an injectable drug that can be used to prevent heartworms in dogs. It is sold under the brand name ProHeart® 12 and ProHeart®  6, made by Zoetis. (6

These medications provide adult dogs with heartworm protection for 12 and 6 months, respectively. They are only effective when given by injection and must be administered by a veterinarian. 

Large Animal Ivermectin

Ivermectin is a drug used to treat parasites in pets and livestock. There are liquid, injectable ivermectin products that are labeled for use only in large animals. One common brand name product is Ivomec® but there are many brands and generic versions available.

cattle and swine ivermectin injection

Dog owners have been known to buy this injectable product from a livestock feed store and give it to their dogs orally as a heartworm preventive.

Don’t be tempted to give large animal ivermectin injectable medication to your dog orally!

I don’t recommend that dog owners use liquid injectable ivermectin labeled for livestock as either an injection or as an oral medication. 

Since the product is made for use in cattle and swine, it is very concentrated, making it very easy to overdose dogs (especially small ones). Ivermectin overdosage in dogs can cause neurological symptoms such as tremors, excessive drooling, seizures and death. (4)

You may also find advice on the internet recommending you give your dog horse oral deworming pastes that contain ivermectin. These are also very concentrated and can easily cause toxicity and death in dogs. Please don’t give them to your dog!

horse ivermectin oral paste

Oral Liquid Heartworm Medicine for Dogs

There are no commercially available oral liquid heartworm medicines for dogs in the U.S.

I just told you why you should not attempt to use cattle injectable ivermectin orally for your dog as a heartworm preventive. Please don’t take advice from non-veterinarians on the internet or elsewhere telling you that it’s safe. 

What About Using Compounding Pharmacies?

I’ve had clients ask if they could have a compounding pharmacy make up a liquid heartworm preventive medication for their dog. It might be feasible in a few situations, but you’ll have to ask your veterinarian as this is a regulatory gray area.

The American Heartworm Society does not recommend compounding heartworm preventives. (3) There cite concerns about accurate dosing, instability and effectiveness of compounded liquid heartworm medication.

Can I Crush My Dog’s Heartworm Pill and Mix It With Liquid?

Some dog owners might be tempted to crush a heartworm pill and mix it with their dog’s food or some other edible liquid. 

This method is not recommended because we don’t know if the active ingredients will still be effective when given this way. You risk your dog getting a heartworm infection and the drug manufacturer would most likely not stand behind any guarantee of effectiveness. 

You must follow the directions on the medication label if you want to be assured of protection against heartworm disease!


No commercially available oral liquid heartworm medications are available for dogs in the United States. Crushing heartworm pills to mix in liquid is not in line with the labeled uses of these medications.

Veterinarians and drug manufacturers do not recommend using livestock drugs for heartworm prevention in dogs due to the risk of toxicity. 

Compounding pharmacies may be permitted to create a liquid heartworm preventive in special cases. 

Topically applied liquid heartworm medicine like Advantage Multi is a good option for dogs who won’t take a chewable pill. The long-acting injectable heartworm preventive ProHeart is another alternative to consider. 

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Related Posts

  1. Advantage Multi® for Dogs and Cats | For Veterinary Professionals. (n.d.). Retrieved October 31, 2022, from https://my.elanco.com/us/advantage-multi-dogs
  2. Coraxis® (moxidectin) for Dogs | For Veterinary Professionals. (n.d.). Retrieved October 31, 2022, from https://www.elancodvm.com/our-products/coraxis/coraxis-topical-solution-dogs
  3. Heartworm Guidelines. (2022, October 31). American Heartworm Society. https://www.heartwormsociety.org/veterinary-resources/american-heartworm-society-guidelines
  4. Hopper, K., Aldrich, J., & Haskins, S. C. (2002). Ivermectin toxicity in 17 collies. Journal of Veterinary Internal Medicine, 16(1), 89-94.
  5. IVOMEC 1% Injection for Cattle and Swine. (n.d.). Drugs.com. Retrieved October 31, 2022, from https://www.drugs.com/vet/ivomec-1-injection-for-cattle-and-swine.html
  6. ProHeart 12. (n.d.). Zoetis Petcare. Retrieved October 31, 2022, from https://www.zoetispetcare.com/products/proheart
  7. Revolution Plus: Nothing should come between you and your cat. (n.d.). Zoetis US. Retrieved October 31, 2022, from https://www.zoetisus.com/products/cats/revolution-plus/index.aspx