The Path to Preventing Canine Lyme Disease

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A recent Companion Animal Parasite Council (CAPC) study found that Lyme disease prevalence is on the rise, not only increasing in endemic states but also spreading to previously nonendemic states.¹

The Positive Lyme Test

As of August, Antech Diagnostics and IDEXX have received over 250,000 positive Lyme test results in 2019 alone.² Each of these positive tests represents a pet that was exposed to Lyme disease—or in other words, a lack of tick prevention.

Unlike with other diseases, previous Lyme exposure does not guarantee future immunity.^3,4 Dogs exposed to Borrelia burgdorferi produce antibodies for one of several outer surface proteins (Osps).^3–5 However, B burgdorferi routinely varies the expression of its Osps—and therefore its antigenic stimulus—to evade the host immune response.^3,5,6 

However, key elements of a comprehensive prevention program, such as vaccination, have been shown to be safe even if a pet has been previously exposed.⁷

The Prevention Package

To protect both previously exposed and naïve patients, a comprehensive prevention program should be advocated. Comprehensive prevention includes three main components: environmental control, year-round tick preventives, and vaccination.

Environmental Control

Proper environmental control may reduce tick burden in the home and yard.⁸ Keeping the grass cut low, removing brush, and raking leaves regularly can eliminate potential tick habitats.⁹ Additionally, an edge of wood chips or rocks placed around the edge of the lawn may act as a buffer zone to tick migration.⁹

Year-Round Tick Prevention

B burgdorferi needs 36 to 48 hours to transfer from the gut of the tick to the host.^3,10 Therefore, prompt removal of ticks after attachment may prevent transmission of the disease.^3,11 Visual inspection is not a reliable form of prevention because ticks are easy to miss.

Consequently, year-round tick preventives are critical for effective tick prevention.³ Either fast-kill products that can eliminate the tick before B burgdorferi can be transferred to the patient or products that prevent attachment and feeding are recommended by ACVIM to prevent B burgdorferi transmission.³

Vaccination

Although tick preventives are a reliable form of protection, suboptimal compliance may leave patients unprotected.³ In fact, a recent study has shown that despite veterinarian recommendation for year-round prevention, dog owners purchased on average 6.1 months of prevention per year.¹² Because of variable compliance, vaccination is a prudent third step for comprehensive Lyme protection.

Lyme vaccines primarily target the B burgdorferi Osps.^3,13 OspA, expressed primarily while in the tick's midgut, protects B burgdorferi from the tick's immune response.^3,5 Thus, antibodies produced by vaccines that target the OspA are ingested by the tick during feeding and can start acting on B burgdorferi before it has transferred to the dog.³ OspC is expressed primarily after the tick feeds and plays a role in protecting B burgdorferi from the vertebrate host's immune system.^5,6 As a result, antibodies produced by vaccines that target OspC are effective against B burgdorferi that has already converted its protein expression to infect the dog.³

Certain vaccines, such as Duramune Lyme, increase the spectrum of prevention by targeting multiple Osps including OspA, OspB, OspC, and other antigens.^5,13 In particular, Duramune Lyme has proven 92.2% effective against natural infection in a highly endemic area and 100% effective in a laboratory setting.¹⁴ Duramune Lyme has also been shown to neutralize multiple field isolates of B burgdorferi.¹³ Additionally, the convenient combination with other vaccines results in fewer injections for patients receiving Duramune vaccinations. This can make immunization less stressful for pets and their owners, potentially improving owner acceptance and improving patient protection.

Conclusion

Especially in regions previously considered not to be endemic for Lyme disease, owners may not be aware of the proper steps to protect their dogs from B burgdorferi. Education of owners on a multimodal approach to Lyme disease control is critical to provide comprehensive protection for canine patients.