UPDATE: FDA Extends Deadline for Input on Evaluation of New Heartworm Preventives

UPDATE (August 17) — The FDA announced today that it is extending the deadline for input on how heartworm preventive studies should be evaluated. The extension is a direct result of requests for additional time to submit comments.

Originally scheduled to close on August 22, the comment period will remain open until November 20.

If you have input on how the process could be changed, send your comments through the FDA regulations electronic filing system.

(May 23) — Despite the number of heartworm preventives that have been widely available for decades, the incidence of infection continues to rise. The most recent estimates from the American Heartworm Society indicate that more than 1 million dogs were heartworm-positive in 2016, and heartworm infections are expected to be above average nationwide this year, leaving many of the country’s pets at risk. Although experts point to poor compliance as a leading cause of rising incidence rates, these statistics mark the need for better, more effective preventive medications.

Fortunately, the Food and Drug Administration (FDA) announced today that its Center for Veterinary Medicine (CVM) is stepping up to the challenge.

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“There are gaps in knowledge that have prevented the FDA CVM from fully evaluating which alternative approaches are suitable for meeting the standards of effectiveness,” the administration wrote in its announcement.

To bridge these gaps, investigators are seeking input on how heartworm preventive studies should be evaluated.

Currently, canine heartworm medications are shown to be effective after sponsors conduct 2 laboratory dose confirmation studies and 1 multisite field safety and effectiveness study under the principles of Good Clinical Practice. But the FDA CVM believes this process has various limitations due to the evolving susceptibility of Dirofilaria immitis larvae to heartworm preventives containing macrocyclic lactones.

Globally, heartworm preventives are still largely effective, but veterinarians should be aware that resistant biotypes of D immitis have been confirmed.

To help produce more effective preventive medications, the FDA CVM is requesting public comment on alternative approaches for evaluating new heartworm preventives or developing study designs. Specifically, the center is looking for input on the following topics:

• Defining an appropriate population-level effectiveness endpoint
• Assessing exposure to infective D immitis larvae in a clinical setting
• Outcome assessment for effectiveness

As a veterinarian, you play a vital role in educating clients and engaging in conversations about proper heartworm prevention, and now you can help with the future of preventive medicine for this ever-growing issue.

If you have input on how the process could be changed, send your comments through the FDA regulations electronic filing system by August 22.