- CAPC forecasts continued geographic expansion of major vector-borne diseases in dogs, including Lyme disease, heartworm, ehrlichiosis, and anaplasmosis.
- Lyme disease risk is spreading beyond traditional hotspots into parts of the Midwest, Southeast, and Northern Plains.
- Heartworm remains entrenched in the Southeast but is expanding northward and into regions like the Mountain West and Northern California.
- Tick-borne diseases are increasing as tick populations expand their geographic range.
- CAPC’s forecasting model is based on over 10 million diagnostic tests annually and has historically achieved over 94 percent accuracy.
- Year-round prevention and annual testing are now essential, even in historically low-risk areas.
- The data also serves as a One Health early warning system, signaling risks to both pets and humans.
The Companion Animal Parasite Council has released its 2026 Pet Parasite Forecast, projecting continued expansion of vector-borne disease risk across the United States. The annual forecast highlights shifting geographic patterns for Lyme disease, heartworm, ehrlichiosis, and anaplasmosis, driven by environmental, ecological, and human factors.
Expanding disease footprint across regions
The 2026 forecast shows Lyme disease continuing to expand beyond its historic strongholds in the Northeast and Upper Midwest. Risk is increasing across states including Illinois, Indiana, Kentucky, Tennessee, and North Carolina, with further spread projected into the Northern Plains.
Heartworm disease remains highly prevalent in the Southeast but is moving northward along the Mississippi River corridor and Atlantic coast. Emerging pockets of risk are also appearing in the Mountain West and Northern California, areas not traditionally considered endemic.
Meanwhile, ehrlichiosis and anaplasmosis are expanding in parallel with tick population growth. Lone star ticks and brown dog ticks are extending their geographic range, increasing exposure risk in both new and existing regions.
Drivers behind the shift
Multiple factors are accelerating the spread of vector-borne diseases, including climate change, land use shifts, wildlife movement, and increased pet travel. These forces are reshaping when and where parasites thrive, leading to less predictable transmission patterns.
Disease expansion is not occurring in straight lines, making localized surveillance and forecasting tools increasingly important for veterinary decision-making.
A data-driven early warning system
CAPC’s forecasts are built on more than a decade of surveillance and analysis of over 10 million veterinary diagnostic test results per disease each year. Historically, the models have achieved more than 94 percent accuracy when compared with real-world diagnostic outcomes.
This dataset enables national and county-level forecasting, providing veterinarians with forward-looking insights into disease risk before cases surge in clinical settings.
The organization also emphasizes broader public health implications. Because dogs often serve as sentinels for human exposure, rising infection rates in pets can signal increased risk for people, reinforcing the importance of a One Health approach.
Year-round prevention becomes standard of care
CAPC underscores that consistent, year-round parasite prevention and annual diagnostic testing are no longer optional. Even in areas previously considered low risk, transmission can occur due to expanding vector ranges and indoor tick survival.
Routine testing remains critical for understanding local disease dynamics, while preventive products that repel or kill ticks and mosquitoes before transmission occurs continue to serve as the foundation of protection.
Additional forecasting tools available
In addition to the annual forecast, CAPC provides 30-day parasite forecasts and daily flea tracking tools through its Pet Disease Alerts platform. These resources offer localized insights to help veterinarians and pet owners tailor prevention strategies based on real-time and projected risk.
Information sourced from the company’s press release.
