The Importance of Screening for Vector-Borne Disease

If you ask your fellow veterinarians if they're concerned about the increased risk of vector-borne disease (VBD) in pets, the answer is almost always "yes." Yet, when you ask if they'd recommend comprehensive VBD screening for dogs every year, the answer is too often "no."

But, why is that?

Why aren't veterinarians recommending comprehensive VBD testing in every dog, every year, if it's the safest option? Why would we risk the chance of letting VBD go undetected in our patients?

Reports of Vector-Borne Disease

As mosquitoes and ticks expand into new regions and humans move around the United States with their pets, routine comprehensive VBD screening should be a part of every patient's preventive care plan — regardless of geographic location.

According to JAVMAnews, veterinarians across the country have seen a significant increase in tick-borne disease cases, including canine Lyme, canine anaplasmosis, and canine ehrlichiosis. There has also been a report of approximately 50,000 human cases of VBD in the U.S. each year, 80% of which are associated with ticks.

The forecast maps generated by the Companion Animal Parasite Council (CAPC) show a widespread increase in heartworm activity and alarming changes in the regional distribution of VBD as well.

3 Reasons Veterinarians Don't Always Screen for VBD

Oftentimes, veterinarians may not recommend comprehensive VBD screening because of logistics, not medicine. Although it can be difficult to implement new protocols with your clients and patients, VBD screening is critical to the health of a pet. Here's why some veterinarians may not screen for vector-borne diseases.

1. Lack of Prevalence in an Area

Some veterinarians may claim that they don't screen their patients for VBD because it's not commonly found in their areas. However, according to data from CAPC, heartworm — along with Ehrlichia spp., Lyme, and Anaplasma spp. — has been detected in each of the 50 states. With the increased mobility of people, pets, and rescue animals, VBD can and will be found anywhere we're testing for it. Even if heartworm or tick-borne diseases are not considered endemic in your region, trying to keep track of which patients are local and which have traveled is more difficult than including the VBD screen as part of their annual preventive care.

Another missed screening opportunity happens when a heartworm test is submitted alone without the added benefit of screening for tick-borne diseases. As reported by CAPC, veterinarians screened almost twice as many dogs for heartworm disease as they did for evidence of tick-borne diseases in 2020. However, even with the rising prevalence of tick-borne diseases, there are some discrepancies.

For example, the CAPC data for Illinois shows that 451,780 tests for canine Lyme disease were submitted in 2020 and 10,980 were positive. In the same state, 735,094 heartworm tests were reported with 7,328 positive results. In New Jersey, 20,239 of the 271, 304 dogs tested for Lyme were positive compared to only 2,351 positives of the 451,772 tested for heartworm. In Oregon, where neither heartworm nor tick-borne diseases are considered endemic, 566 of the 115,585 dogs screened for heartworm tested positive while 507 of the only 65,244 dogs screened for tick-borne diseases tested positive for Ehrlichia spp.

The CAPC numbers show that veterinarians submit a significantly higher number of heartworm tests compared to complete screens that include the tick-borne diseases. The numbers also indicate that this doesn't make sense from a patient wellness standpoint, since even in areas with higher reported numbers of tick-borne diseases, the number of dogs tested for heartworm is close to 50% more.

2. Cost of Screening

As veterinarians, we tend to worry a lot about cost to our clients — oftentimes more than the clients themselves. By assuming our clients won't want to pay more for a comprehensive panel, we're not giving them the choice to prevent full-blown or chronic disease in their pets. When looking at the big picture for your clients, screening for VBD is less expensive than treating a pet who becomes ill due to infection by one of these pathogens. You can't put a price tag on the illness a patient may endure secondary to chronic disease or the emotional consequences for their owners if they lose their pet. Our clients come to us for expert advice, not to help balance their budgets. It is our responsibility to recommend the best care and to recognize that our clients are capable of making informed decisions.

Many clients are already opting for heartworm testing. Why not expand to a more comprehensive screen? The cost of an expanded in-house or reference lab test that includes the most common tick-borne disease is usually only marginally different from testing for heartworms alone. There's more "bang for the buck" when it comes to our clients' pockets and the health of our patients. Be sure to also share preventive care materials with your clients to ensure that they have all of the information they need up front.

3. Uncertainty of Process

Some veterinarians may not test their patients for VBD because they aren't sure what to do once they have a case with a positive result, especially if the patient is asymptomatic. In order to address this common concern, some comprehensive tests include reference guides for veterinarians, and they outline how to proceed with positive or negative results in both symptomatic and asymptomatic dogs. It's also great for quick reference material, providing images of the most common tick species that can transmit these pathogens, their geographic distribution, and a summary of each of the six pathogens included in the screening, along with clinical signs and progression of the disease.

Testing for pathogens has become part of everyday conversation for most people thanks to the COVID-19 pandemic. Our clients are more aware of the effects of not diagnosing and not treating an infectious disease. How would they feel if they knew they weren't given the option to rule out infectious disease in their pet with a simple blood test?

As veterinarians, it is our responsibility to recommend what's best for our patients and for public health. Vector-borne diseases are spreading across the country, putting both animals and humans at risk. We can contribute to surveillance and understand the success of preventives by recommending comprehensive VBD screening every year for every dog.

Nell Ostermeier
DVM, CVA, FAAVA

Dr. Ostermeier is an entrepreneur at heart and operates peopleandpet.com, a virtual practice providing telehealth and education for pet parents as well as consultations for veterinarians who wish to safely integrate holistic options into conventional medicine. She earned her DVM from the University of Illinois in 2004 and, since that time, has worked with multiple species and performed varied roles, including associate veterinarian, relief veterinarian, and practice owner. Dr. Ostermeier is an expert in integrative medicine and veterinary acupuncture, and she has spoken at conferences around the world. As an IDEXX regional thought leader, she supports veterinarians in promoting diagnostics as the basis for best preventive care and individualized treatment plans. The views and opinions in this piece are the authors own, and do not necessarily reflect the views of either The Vetiverse or IDEXX.


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