Improving Access to Heartworm Treatment

The incidence of canine heartworm disease continues to rise across the United States. While effective treatment guidelines have been established by the American Heartworm Society (AHS), not all pet owners can afford the costs of sick and emergency care veterinary services. In response to this challenge, Emancipet has developed and implemented a lower-cost, technician-leveraged heartworm treatment protocol based on AHS guidelines and tailored to high-volume outpatient community clinic settings. In collaboration with the ASPCA, Emancipet has published a study that documents the safety and effectiveness of the protocol.

By employing this protocol, veterinary care providers can significantly reduce the cost of treating heartworm disease, thus increasing access to high-quality treatment and alleviating financial barriers for pet owners.

Study Design

This prospective study was conducted at two of Emancipet’s high-volume, low-cost community clinics in Austin and Houston, Texas, between February 2020 and December 2021. A total of 556 dogs with heartworm disease and who met other study inclusion criteria participated in the study. 

The treatment protocol followed the AHS guidelines for heartworm treatment, with only minor modifications to optimize treatment outcomes within a high-volume outpatient clinic setting. These modifications included:

• Conducting pre-treatment bloodwork only.
• Administering pre-injection sedation.
• Providing post-injection pain medication.
• Implementing a reduced exercise restriction period.

To maximize efficiency and help minimize costs, trained veterinary technicians and veterinary assistants, under the supervision of a licensed veterinarian per the Texas Veterinary Licensing Act, were responsible for patient check-in, gathering medical histories, performing diagnostics, administering melarsomine injections, dispensing prescribed medications, and monitoring and discharge patients, which allowed for treatment of up to 25 dogs per day.

Costs were also reduced by minimizing ancillary diagnostics and implementing short in-clinic observation periods post-injection. Patients were monitored post-injection for 2.5–4.5 hours in the clinic, with clear instructions provided to pet owners to continue monitoring after discharge and to report any complications. 

Pet owners also completed self-administered questionnaires at each appointment that asked about adverse events, adherence to medication administration, and exercise restrictions.

Retention of patients, adverse reactions, and therapy adherence were assessed throughout treatment.

Study Results

• Treatment costs ranged from $225 to $614 per patient, but no pet owner was turned away due to financial limitations.
• 97% of patients completed the three-injection series.
• 1-month post-injection, 99% of patients tested negative for microfilariae, while 99% of those returning for testing at 9 months post-injection tested negative for antigen (evidence of no adult female heartworms)
• Adverse reactions were observed in 90% of patients over the entire treatment series, with the most frequently reported types being behavioral (such as panting, whining, and reluctance to move) and injection site reactions (pain or swelling). Adverse events decreased after each injection time.
• Only 4.6% of owners sought additional medical care for adverse reactions during treatment, and the overall mortality rate stood at 1.3%.
• Average adherence to exercise restriction (a common challenge for all heartworm treatment protocols) was more than 75% throughout treatment.

Study Takeaways

This study is the largest prospective clinical study based on AHS guidelines to date and is the first to evaluate heartworm treatment in a high-volume outpatient clinic setting. 

Findings are consistent with those previously reported in private practice/tertiary centers and demonstrate that effective and safe heartworm disease treatment can be provided at lower cost by using a technician-leveraged, high-volume model.

By implementing this protocol, veterinary care providers can significantly reduce the financial burden associated with heartworm treatment, thereby enhancing accessibility without compromising quality care.

This study represents a significant step forward in expanding access to high-quality heartworm treatment, reaffirming the importance of innovative approaches in addressing critical healthcare needs within the companion animal community.

For more information about the study or protocol, please contact the corresponding author and Chief Medical Officer, Dr. Holly Putnam, DVM, at holly.putnam@emancipet.org.