Longer tick and allergy seasons are reshaping year-round parasite and dermatology care

Tick season and allergy season are both running longer than the calendar used to suggest. Weekly human emergency department visits for tick bites hit their highest levels for this time of year in nearly a decade this summer, with every US region except the South Central states posting rates not seen since tracking began in 2017, according to data the CDC released in the spring.¹

An estimated 31 million Americans are bitten by ticks annually, and the agency estimates that approximately 476,000 people are diagnosed with Lyme disease each year.¹ Ticks don't distinguish between human and animal hosts, so a longer exposure window for people generally tracks with a longer exposure window for the pets that share their yards, trails, and homes.

The allergy picture is moving in the same direction. A Climate Central analysis of temperature data from 1970 to 2025 found that the freeze-free growing season has lengthened by an average of 21 days in 87% of the 198 US cities studied, with some Western cities gaining more than 2 additional months of freeze-free days.²

What it means for veterinary clinic caseloads

Elanco Animal Health, which sells parasiticide and dermatology products for pets, pointed to these same trends this month to explain stronger-than-expected demand across its US and international pet health businesses. The company said organic revenue in those businesses grew 9% year over year in the first half of 2026.³ Jeff Simmons, CEO of Elanco, framed the shift as a structural change in caseload rather than a seasonal blip: "Elanco's momentum reflects our new innovation increasing the standard of care against growing pet health threats, underscoring market durability and our commitment to customers."³

Bobby Modi, Elanco's executive vice president of US pet health, connected the exposure data directly to counseling conversations in the exam room, describing pets as sitting between environmental and human health risk. "Speed of kill isn't just a clinical metric; it's a household safety requirement," Modi said of parasite control in general.³

The fundamentals of treating tick-borne disease or allergic dermatitis haven’t changed, but the data raise a fair question for practices: Do client conversations about tick and allergy prevention still make sense confined to the traditional "season," or has that window already shifted?

References

1. CDC data show weekly ER visits for tick bites higher than usual. News release. CDC. April 23, 2026. Accessed September 16, 2026. https://www.cdc.gov/media/releases/2026/2026-cdc-data-show-weekly-er-visits-for-tick-bites-higher-than-usual.html
2. Warmer growing season, longer allergy season. Climate Central. March 4, 2026. Accessed September 16, 2026. https://www.climatecentral.org/climate-matters/2026-allergy-season
3. Expanding tick and itch season supports momentum in Elanco Innovation, meeting pet owner demand for health and wellness care. News release. Elanco Animal Health. September 15, 2026. Accessed September 16, 2026. https://www.prnewswire.com/news-releases/expanding-tick-and-itch-season-supports-momentum-in-elanco-innovation-meeting-pet-owner-demand-for-health-and-wellness-care-302878359.html