When Should Puppies Start Heartworm Preventatives?

Heartworm disease is a serious and potentially life-threatening condition that affects dogs of all ages, including puppies. For pets in Corpus Christi, where warm temperatures and mosquitoes are common year-round, heartworm prevention is not optional - it’s essential. Knowing when to start your puppy on heartworm preventatives can help protect them from the very beginning and set them up for a healthy life.

What Is Heartworm Disease?

Heartworm disease is caused by parasitic worms transmitted through mosquito bites. Once infected, the worms grow and live in the heart, lungs, and surrounding blood vessels, leading to long-term organ damage and, in severe cases, death. Treatment for heartworm disease is costly, lengthy, and carries significant health risks, which is why prevention is always the best approach.

When Should Puppies Start Heartworm Preventatives?

Most puppies should begin heartworm prevention as early as 6 to 8 weeks of age. At this stage, puppies are young enough that infection is unlikely, and preventive medications are safe and effective when prescribed appropriately by a veterinarian.

Starting early ensures:

• Continuous protection during a puppy’s most vulnerable months

• Reduced risk of accidental gaps in prevention later

• Easier integration into a lifelong health routine

Even puppies that spend most of their time indoors are at risk, as mosquitoes can easily enter homes.

Is Heartworm Testing Necessary for Puppies?

Puppies younger than 7 months of age can typically begin heartworm preventatives without prior testing. However, once a dog is older than 7 months and has not been on consistent prevention, a heartworm test is required before starting medication. This is important because giving preventatives to a dog with an existing infection can cause complications. Your veterinarian will recommend the appropriate testing schedule based on your puppy’s age, health, and medical history.

Why Year-Round Prevention Is Important

In warm, humid climates like South Texas, mosquitoes don’t disappear for long periods of time. This means heartworm risk exists throughout the year - not just during summer months. Skipping doses or stopping preventatives during cooler seasons can leave your puppy unprotected and vulnerable to infection. Consistent, year-round prevention is the most reliable way to protect your puppy as they grow into adulthood.

Get Expert Care for Your Puppy’s Preventive Health

Puppies should begin heartworm preventatives as early as 6 to 8 weeks of age to ensure early and consistent protection against a dangerous disease. In mosquito-prone areas like Corpus Christi, year-round prevention is essential for keeping your puppy healthy and avoiding the risks and costs associated with heartworm treatment.

If you’ve recently welcomed a puppy into your home and have questions about heartworm prevention, the team at Animal Hospital of Padre Island is here to help. Visit our facility in Corpus Christi, Texas, or call (361) 949-8200 today.