What Age Can You Give Puppy Heartworm Medicine?

Giving your puppy heartworm medicine is an important part of their preventative healthcare routine. Heartworms are parasites that can live in the heart, lungs, and blood vessels of dogs, and can cause serious illness or even death if left untreated.

So, at what age can you give your puppy heartworm medicine? The answer depends on the specific product you are using and the advice of your veterinarian. Here are some general guidelines to follow:

  • Most heartworm preventative medications are safe for puppies as young as 8 weeks old. However, puppies this young may not have developed immunity to some of the parasites that heartworm preventatives target, so they may still be at risk of infection.
  • It’s generally recommended to wait until your puppy is at least 12 weeks old before starting them on heartworm preventative medication. By this age, most puppies have received their full set of vaccinations and have developed a stronger immune system, which can help protect them against infection.
  • Some heartworm preventative medications may not be suitable for puppies under a certain weight. For example, the product label may specify that the medication is only safe for puppies weighing more than 2 pounds. Make sure to check the product label and consult with your veterinarian before giving your puppy any medication.
  • Follow your veterinarian’s recommendations for when to start giving your puppy heartworm medicine. They will consider factors such as your puppy’s age, weight, and overall health when determining the appropriate time to start treatment.

In addition to giving your puppy heartworm medicine, there are a few other steps you can take to help protect them against heartworm infection:

  • Keep your puppy on a leash when walking or playing outside, as this can help prevent them from coming into contact with infected mosquitoes.
  • Use mosquito repellent when you’re outside with your puppy, especially during the warmer months when mosquitoes are most active.
  • Keep your puppy’s bed and sleeping areas clean and free of debris, as this can help reduce their risk of exposure to heartworm-carrying mosquitoes.

By following these guidelines and working closely with your veterinarian, you can help ensure that your puppy stays healthy and protected against heartworm infection.


Hannah Elizabeth is an English animal behavior author, having written for several online publications. With a degree in Animal Behaviour and over a decade of practical animal husbandry experience, Hannah's articles cover everything from pet care to wildlife conservation. When she isn't creating content for blog posts, Hannah enjoys long walks with her Rottweiler cross Senna, reading fantasy novels and breeding aquarium shrimp.

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