Best Heartworm Prevention for Cats: 5 Vet-Approved Picks

While heartworms prefer to infect dogs instead of cats, this mosquito-transmitted parasite is still a major health risk to cats. Although the exact prevalence of heartworms in cats differs by geographic location, the estimated prevalence in cats is around 5–20 percent of the rate in unprotected dogs [1]. This means for every 100 infected dogs, there are five to 20 infected cats.

By using heartworm prevention for cats, pet parents can protect their cats from potentially deadly heartworm infestations. Find out everything you need to know about cat heartworm prevention, as well as several vet-approved picks to consider.

Why Do Cats Need Heartworm Prevention?

Heartworm prevention for cats is the most effective method for protecting your cat from feline heartworm disease. The following are specific reasons that cats need year-round heartworm prevention:

Heartworms have been diagnosed in all 50 states, in all seasons of the year, and in indoor-only cats. 

Dogs, foxes, and coyotes are all important vectors for heartworms. The wind can blow mosquitoes for miles, easily carrying heartworms from an infected canine to your cat. It only takes one bite from an infected mosquito for your cat to contract heartworms. These mosquitoes can enter your home and infect indoor cats, too. In fact, the American Heartworm Society notes that one study found that 25 percent of cats with heartworms were considered indoor-only [2].

There is no approved treatment for adult heartworm infestations in cats. 

Thus far, no study has shown that any form of therapy that kills adult heartworms increases the survival rate in cats. Unfortunately, many cats with heartworms have to be managed symptomatically, usually taking steroids for lung disease. These cats have to stay on prevention to keep the worms from reproducing while waiting for the worms in their hearts to die, which can take years. During this wait, the worms can cause damage to the cat’s heart and lungs.

Heartworms have a relatively high fatality rate in cats. 

While around 80 percent of cats will manage to self-cure their heartworm infestation, around 10-20 percent will experience sudden death [3]. 

Types of Heartworm Prevention for Cats

Cat heartworm medicine comes in two basic forms—oral and topical. Oral heartworm prevention for cats can include tablets or pills. Topical heartworm medications for cats are usually applied to the skin at the base of the skull or back of the neck. Most cat heartworm prevention medicines are given once monthly.

Heartworm preventatives on the market belong to the macrocyclic lactone class of antiparasitic drugs and include drugs like: 

• Milbemycin oxime
• Moxidectin
• Selamectin

Most heartworm medication for cats also provides coverage against several intestinal worms. You may also notice combination products that extend coverage to fleas and/or ticks. 

Heartworm prevention for cats requires a prescription from a veterinarian. 

Best Heartworm Prevention for Cats: 5 Vet-Approved Picks

Your veterinarian will help you pick the best heartworm preventative for your cat. There are other great products that we have not included on this list, and your veterinarian may recommend a different product from the ones we’ve included in this review.

The following products are not listed in any specific order.

Revolution Plus

Revolution Plus is a topical heartworm preventative for cats that includes the drugs selamectin and sarolaner. This medication is applied monthly to the skin at the base of the neck in front of the shoulder blades.

Revolution Plus prevents heartworm disease; treats and controls roundworms, intestinal hookworms, and ear mites; and kills adult fleas. Because it can kill adult fleas, it helps to prevent tapeworm infestations in cats. Revolution Plus can also treat and control four species of tick infestations in cats. 

Cats taking Revolution Plus should be at least 8 weeks old and weigh at least 2.8 pounds. Dosing is based on the cat’s weight. 

Pet parents should also note that the drug sarolaner is part of the isoxazoline drug class. Isoxazolines have rarely been associated with neurologic adverse effects, including tremors, an uncoordinated gait (i.e., ataxia), and seizures. This preventative should be used with caution in cats who have a history of seizures or other neurologic conditions.

There is also a topical product called Revolution, which contains only selamectin. This product protects against heartworms, fleas, roundworms, hookworms, and ear mites. Without sarolaner, the product does not protect against ticks.

Advantage Multi

Advantage Multi is a topical heartworm preventative for cats that includes the drugs moxidectin and imidacloprid. This medication is applied monthly to the skin at the base of the neck in front of the shoulder blades. 

Advantage Multi prevents heartworm disease; kills adult fleas; and can treat and control ear mites, hookworms, and roundworms in cats.

Cats taking Advantage Multi should be at least 9 weeks old and weigh at least 2 pounds. Dosing is based on the cat’s weight. 

NexGard Combo

NexGard Combo is a topical heartworm preventative for cats that includes the drugs eprinomectin, esafoxolaner, and praziquantel. This medication is applied monthly to the skin on the neck between the base of the skull and the shoulder blades.

NexGard Combo prevents heartworm disease in cats; treats and controls roundworms, hookworms, and tapeworms; kills adult fleas and prevents flea infestations; and treats and controls two species of tick infestations in cats.

Cats taking NexGard Combo should be at least 8 weeks old and weigh at least 1.8 pounds. Dosing is based on the cat’s weight. 

Like sarolaner in Revolution Plus, the esafoxolaner in NexGard Combo is part of the isoxazoline drug class. Isoxazolines have rarely been associated with neurologic adverse effects, including tremors, an uncoordinated gait (i.e., ataxia), and seizures. This preventative should be used with caution in cats who have a history of seizures or other neurologic conditions.

Bravecto Plus

Bravecto Plus is a topical heartworm preventative for cats that includes the drugs moxidectin and fluralaner. This medication is applied every two months to the skin at the base of the skull.

Bravecto Plus prevents heartworm disease, treats roundworms and hookworms, kills adult fleas, prevents flea infestations, and treats and controls three species of ticks in cats. 

Cats taking Bravecto Plus should be at least 6 months old and weigh at least 2.6 pounds. Dosing is based on the cat’s weight. 

The fluralaner in Bravecto Plus is part of the isoxazoline drug class. Isoxazolines have rarely been associated with neurologic adverse effects, including tremors, an uncoordinated gait (i.e., ataxia), and seizures. This preventative should be used with caution in cats who have a history of seizures or other neurologic conditions.

Interceptor

Interceptor is an oral heartworm preventative for cats that includes the drug milbemycin oxime. The medication is given by mouth every month and is a chewable, beef-flavored tablet. This drug may be a good option for pet parents looking for heartworm pills for cats instead of topical preventatives.

Interceptor prevents heartworm disease and treats hookworm and roundworm infestations in cats. 

Cats taking Interceptor should be at least 6 weeks old and weigh at least 1.5 pounds. Dosing is based on the cat’s weight.

How to Choose a Heartworm Preventative for Cats

Your veterinarian will help you choose the best heartworm preventative for your cat. Considerations include:

• Your cat’s willingness to take an oral medication
• Whether your cat has had a reaction to preventatives in the past
• Any active parasite infestations your cat has 
• Your cat’s age and weight
• Your cat’s medical history, especially food allergies and neurologic conditions
• Other pets or children in the home who may come in contact with topical preventatives
• How often you want to give prevention (monthly vs. every two months)
• Financial restrictions

It may take a little experimenting to find which product your cat tolerates best. Make sure to let your veterinarian know if your cat develops any adverse effects after taking heartworm prevention.

Cat Heartworm Medicine FAQ

Can I buy heartworm medication for cats over the counter?

Heartworm medication for cats is not available over the counter. These medications require a veterinary prescription.

Do indoor cats need heartworm prevention?

Yes, indoor cats should be kept on heartworm prevention. Around one-fourth of heartworm infestations in cats are thought to occur in cats considered indoor cats.

Is a cat heartworm test necessary before starting a preventative?

Yes, heartworm testing is necessary before starting a preventative. If a cat is heartworm positive, giving preventatives can lead to a rare but possibly severe reaction.

How often do cats need heartworm medicine?

Cats should be kept on heartworm medicine year-round. Most heartworm medicines for cats are given monthly. Bravecto Plus needs to be given every two months.

References

1. Nelson, C Thomas, and Calvin M Johnson. “Evaluation of feline heartworm disease based on gross necropsy, serology, pulmonary histopathology, and radiographic evidence in adult shelter cats in northeastern Alabama.” Parasites & vectors vol. 17,1 161. 29 Mar. 2024, doi:10.1186/s13071-024-06178-9
2. “Current feline guidelines for the prevention, diagnosis, and management of heartworm infection in cats.” American Heartworm Society. 2014. Retrieved from https://heartwormsociety.org/images/pdf/2014-AHS-Feline-Guidelines.pdf
3. Brooks, Wendy. “Heartworm infection in cats.” VeterinaryPartner. Rev. April 20, 2023. Retrieved from https://veterinarypartner.vin.com/default.aspx?pid=19239&id=4951471