Pet owner compliance a barrier to heartworm prevention

by Claire Walther, DVM, Zoetis Veterinary Specialty Operations

It has been recognized in veterinary medicine that compliance with pet owner administered medication has been historically low. A review of several compliance studies across human and veterinary medicine reveals that 100% compliance with medication ranged from 7-55%1-4. Interestingly, medication compliance rates remain low despite the duration of medication, patient type and severity of the disease.  

  • When pet owners were asked to administer a short course, 10 day, of antibiotics to their pet; the pet received only 44% of doses within the optimum time-period.1
  • Another demonstrated that parents were not more proficient with their child’s medication, only adhering to prescribed dosing regimen 7.3% of the time.2
  • Even diseases with severe symptoms and potential of death did not impact overall compliance rates. A review of the adherence to prophylaxis post exposure to anthrax in 2001 demonstrated that only 40% of postal workers completed the prophylactic treatment. Four postal workers developed inhalation anthraxis and 2 succumbed to the disease.3

In veterinary medicine, our assessment of compliance follows suit. When evaluating heartworm prevention compliance, 2 out of 3 dogs leaves the practice without even a single dose of heartworm prevention. Of the select few pet owners that purchase heartworm prevention, they administer less than 75% of the doses.5

An American Heartworm Society (AHS) survey on the incidence of adult heartworm infections in dogs showed a 21.7% increase in the average cases per veterinary clinic between 2013-2016.5 During that time, the proportion of dogs receiving heartworm prevention remained unchanged. Total lack of preventive use, pet owner non-compliance and the emergence of heartworm resistance to macrocyclic lactones have been proposed to be contributing to the rise in heartworm incidence in the United States.5

Heartworm incidence is on the rise; heartworm prevention compliance remains unchanged. The pattern must be broken to change the potentially devastating trajectory of this disease. We don’t need to look far – livestock and nematodes – to see what our future may look like.

The quote “insanity is doing the same thing over and over and expecting different results” applies here. As an industry, the commitment should be made to try to eradicate the spread of heartworm disease. The first and simplest step that is in our control- improving pet owner compliance.

A study showed that we can improve pet owner compliance by making it easy for pet owners to fit heartworm prevention into their normal routines and inform them about the risks of the disease and how heartworm prevention works.4 

Annual wellness exams provide us the best opportunity to educate, foster positive relationships and provide heartworm prevention in hospital that does not disrupt the pet owner’s routine. The simplest solution is injectable preventions that guarantee compliance and do not depend on monthly pet owner remembrance.

As a community, the time is now to ditch the apathy about heartworm disease and make a real impact in the future of our field, patients and practices.


1.       K. Grave, H. Tanem. Compliance with short‐term oral antibacterial drug treatment in dogs. JSAP. 28 June 2008

2.       M.D. Mary E. Mattar, M.D. James Markello, M.D. Sumner J. Yaffe; Inadequacies in the pharmacologic management of ambulatory children. The Journal of Pediatrics. Volume 87, Issue 1, July 1975, Pages 137-141

3.       Mariaelena D. Jefferds,et al. Adherence to Antimicrobial Inhalational Anthrax Prophylaxis among Postal Workers, Washington, D.C., 2001. Emerg Infect Dis. 2002 Oct; 8(10): 1138–1144.

4.       Berendsen, M and Knol BW. Tijdschrift Voor Diergeneeskunde. Sept 2002. 127(18): 548-551.

5.       Jason Drake and Scott Wiseman. Increasing incidence of Dirofilaria immitis in dogs in USA with focus on the southeast region 2013–2016. Parasites & Vectors (2018) 11:39

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