How Often Should Dogs Get Heartworm Tests and Preventive Medication?

Heartworm disease is a serious health concern for dogs, and even a single bite from an infected mosquito can transmit the infection. These parasites can eventually damage the heart, lungs, and surrounding blood vessels. Unfortunately, many dogs show no symptoms during the early stages.

Most dogs need heartworm testing once a year and preventive medication throughout the year. However, puppies, newly adopted dogs, and pets with missed medication doses may require different testing schedules.

At our veterinary practice in Buffalo, we help pet owners understand the importance of consistent heartworm prevention. Knowing when to test your dog, how preventive medications work, and what to do after a missed dose can help protect your pet from a potentially life-threatening disease.

How Often Should Dogs Be Tested for Heartworms?

Most adult dogs should receive a heartworm test every 12 months, even when they take preventive medication regularly. Annual testing helps detect infections that may develop after missed doses or problems with medication administration. 

Heartworm preventives are highly effective, but no medication guarantees complete protection. Testing recommendations also depend on your dog’s age and prevention history.

Heartworm Testing Schedule for Puppies and Adult Dogs

• Puppies younger than seven months: Can generally begin heartworm prevention without an initial test. Testing is recommended approximately six months after starting prevention, six months later, and annually afterward.
• Dogs seven months or older: Should generally receive a heartworm test before starting prevention, followed by another test approximately six months later.
• Adult dogs receiving regular prevention: Should undergo heartworm testing annually.
• Dogs with missed preventive doses: May need additional testing based on their medication history and possible mosquito exposure.

Our vets can determine an appropriate testing schedule during your dog’s wellness examination.

What Happens During a Heartworm Test?

Heartworm testing usually involves collecting a small blood sample. The procedure is relatively quick and can often be performed during a routine wellness appointment.

Veterinarians commonly use two testing methods.

• Heartworm antigen test: Detects proteins associated with adult female heartworms. This is commonly used for routine screening.
• Microfilaria test: Checks for immature heartworms circulating in the bloodstream.

If a dog tests positive, additional diagnostic procedures may be necessary. These can include chest X-rays, ultrasound, or further bloodwork.

Heartworm infections are not immediately detectable after exposure. It generally takes several months for an infection to become detectable through standard testing.

This delay explains why follow-up testing is important when a dog has missed preventive medication.

What Are the Early Signs of Heartworm Disease in Dogs?

Heartworm disease may develop silently, particularly during its early stages.

As the infection progresses, dogs may experience:

• Persistent coughing
• Reduced energy or unusual tiredness
• Difficulty exercising
• Rapid or difficult breathing
• Decreased appetite
• Unexplained weight loss
• Abdominal swelling in advanced cases

Some infected dogs remain active and appear healthy despite carrying heartworms.

Severe infections can interfere with circulation and cause significant damage to the heart and lungs. If your dog experiences sudden weakness, collapse, or breathing difficulties, seek immediate veterinary attention. Annual screening helps identify infections before serious symptoms become apparent.

What Should You Do if Your Dog Misses a Heartworm Prevention Dose?

Missing a preventive dose can increase your dog’s risk of infection, particularly when several weeks or months pass without protection. If your dog misses medication, contact your veterinarian before changing the schedule.

Our vets may consider:

• The type of medication prescribed
• The date of the last administered dose
• The number of missed doses
• Previous heartworm testing results
• Potential mosquito exposure

Depending on these factors, your veterinarian may recommend restarting prevention and scheduling additional testing.

A negative test immediately after a missed dose cannot rule out a recent infection. Never double a preventive medication dose unless your veterinarian specifically recommends doing so.

Can Dogs Still Get Heartworms While Taking Preventive Medication?

Yes. Although preventive medications are highly effective, infections can occasionally occur. Common reasons include missed doses, incorrect administration, or medication given at an inappropriate dose.

Dogs may also remain vulnerable if they vomit an oral preventive shortly after receiving it or if topical medication is applied incorrectly. Rare cases involving heartworm populations with reduced susceptibility to certain preventives have also been documented. These possibilities make annual testing an important part of responsible parasite prevention.

How Can Preventive Pet Care Reduce Heartworm Risks?

Heartworm prevention works most effectively when supported by regular veterinary examinations and consistent medication. At our veterinary practice, we incorporate heartworm screening and parasite prevention into preventive pet care recommendations based on each dog’s individual needs.

Routine Wellness Examinations

Annual appointments allow our vets to assess your dog’s general health and review their parasite prevention history. We can also discuss changes in breathing, energy, appetite, or activity that may require further investigation.

Personalized Prevention Recommendations

Dogs have different levels of parasite exposure depending on their lifestyle. Our veterinary team can recommend suitable preventive medications and explain how to administer them correctly.

Heartworm Testing and Follow-Up

Routine screening helps identify infections that might otherwise remain unnoticed. If your dog has missed medication or has an uncertain prevention history, our vets can recommend appropriate follow-up testing.

Prevention Guidance for Puppies

Puppies benefit from beginning heartworm prevention early. Our team can explain when medication should begin, how frequently it should be administered, and when testing becomes necessary.

What Happens if a Dog Tests Positive for Heartworms?

A positive heartworm screening result requires veterinary evaluation and confirmatory testing. Your veterinarian may recommend additional diagnostics to assess the infection and determine whether the heart or lungs have been affected.

Treatment generally involves medications targeting different stages of the parasite’s life cycle. Strict exercise restriction is also important because physical activity can increase the risk of complications during treatment.

Heartworm treatment may take several months and requires careful monitoring. Preventing infection is generally safer and less complicated than treating established heartworm disease.

Protect Your Dog With Consistent Heartworm Prevention

Heartworm disease can cause serious health complications, but routine testing and preventive medication significantly reduce the risk of infection. Most dogs need annual testing and year-round prevention. Puppies and dogs with interrupted medication schedules may require additional screening. Our veterinary practice helps Buffalo pet owners maintain consistent parasite prevention through wellness examinations, testing, and medication guidance.

Is your dog due for a heartworm test or preventive medication? Contact North Buffalo Animal Hospital today to schedule an appointment. Our veterinary team can review your dog’s prevention needs and help you take the next step toward protecting their long-term health.

Frequently Asked Questions

Q1. Do indoor dogs need heartworm prevention?

Ans. Yes. Mosquitoes can enter homes through doors, windows, and other openings. Indoor dogs should receive year-round heartworm prevention.

Q2. Can puppies receive heartworm medication without testing?

Ans. Puppies younger than seven months can generally begin prevention without an initial test. Follow-up testing is necessary because infections acquired earlier may not be immediately detectable.

3. Is heartworm testing painful for dogs?

Ans. Heartworm testing requires a small blood sample. Most dogs experience only brief discomfort during collection.

Q4. Where can I schedule heartworm testing in Buffalo?

Ans. North Buffalo Animal Hospital provides veterinary care in Buffalo. Contact our team to discuss heartworm testing and schedule an appointment.

Q5. Does North Buffalo Animal Hospital recommend winter heartworm prevention?

Ans. Yes. North Buffalo Animal Hospital recommends consistent year-round heartworm prevention to reduce gaps in protection, including during Buffalo’s colder months.

Q6. Can North Buffalo Animal Hospital help after missed heartworm medication doses?

Ans. Yes. Our vets at North Buffalo Animal Hospital can review your dog’s prevention history and recommend appropriate medication guidance and follow-up testing.