AHS Board Speaks Out

by Brian A Digangi, DVM, MS, DABVP

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Veterinarians today are fortunate to have several point-of-care heartworm tests. In the majority of cases, these D. immitis antigen tests meet practitioners’ needs for speed and accuracy. However, when test results conflict with clinical expectations, the added step of heat pretreatment (HPT) of the sample should be considered.

Q. What can cause a “no antigen detected” result when the patient is infected?

A. Patient-side diagnostic tests rely on the presence of soluble heartworm antigen for the detection of heartworm infection. In cases where soluble antigen is bound to endogenous antibodies, forming an insoluble unit in the bloodstream known as an “immune complex,” the antigen is essentially blocked from detection. This blocking has been linked to several factors:

Is heartworm incidence up or down in your practice area?

by Christopher J Rehm, DVM

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The latest American Heartworm Society Heartworm Incidence Survey has uncovered both challenges and opportunities for veterinarians in practice. On one hand, heartworm incidence has inched upwards in the three years since the AHS survey was last conducted. On the other hand, the power to reverse this upward trend is, quite literally, in our hands.

CHRISTOPHER J. REHM, DVM

APRIL IS HEARTWORM AWARENESS MONTH and the ideal time to discover the many resources available from the American Heartworm Society (AHS). Our goal: to arm you with the knowledge and tools you need to defeat this serious parasite.

CHRIS DUKE, DVM

Q. I’m a big believer in heartworm prevention, but I find myself repeating my “heartworm 101” lecture over and over to clients. Is it worth it?

TOM NELSON, DVM

Q. While the American Heartworm Society (AHS) recommends year-round heartworm prevention for dogs and cats, many veterinarians and owners take a seasonal approach. What is the AHS’ rationale?

by Charles Thomas (Tom) Nelson, DVM

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Q. How significant a problem is heartworm compliance?

A. In a 2014 American Heartworm Society survey, veterinarians were asked if the incidence of heartworm disease in their area had increased over the past three years, decreased or stayed the same.

• Among the 21% of veterinarians who perceived a drop in incidence, 74% attributed the drop to more pet owners administering preventives, while 61% cited more preventives being administered year-round and on time.
• Meanwhile, among the 19% who perceived an increase in heartworm incidence, 61% attributed the rise to poor compliance— either not administering preventives or failing to give doses on time.

STEPHEN JONES, DVM

Q. Why is melarsomine recommended by the American Heartworm Society (AHS), given the potential for complications during adulticide treatment?

MATT MILLER, DVM

Q. The American Heartworm Society (AHS) Guidelines recommend heartworm prevention nationwide. Is it really necessary to use preventives in areas where heartworm is not endemic?

The Role of Control in Heartworm Prevention

by John McCall, MS, PHD

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Q. Mosquitoes are an essential player in the life cycle of Dirofilaria immitis, which causes heartworm infection. What do veterinarians need to know about the role of mosquito control in heartworm prevention?

A. Heartworm disease is considered the most important vector-borne disease of dogs in the U.S. and many other parts of the world. Targeting vectors as part of a preventive approach to controlling mosquito-borne human diseases has been critically important for decades, but has received much less attention in companion animal disease prevention.

CLARKE ATKINS, DVM, DIPLOMATE ACVIM (Internal Medicine and Cardiology)

Feline heartworm disease (HWD) has a low index of suspicion and is significantly under-diagnosed. Knowing when to test cats for HWD—and whether to test them—is important. The challenge boils down to this:  no single test can accurately detect heartworms at all stages in cats. Thoroughly understanding the limitations of antigen and antibody tests is necessary to utilizing these assays with confidence.