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 room 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 roughly 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 the freeze-free growing season has lengthened in 87% of the 198 US cities studied, by an average of 21 days, with some Western cities gaining more than two additional months of freeze-free days.²

What it means for veterinary clinic caseloads

Elanco Animal Health Incorporated, which sells parasiticide and dermatology products for pets, pointed to these same trends this month in explaining stronger-than-expected demand across its US and international pet health businesses, which it said grew organic revenue 9% year over year in the first half of 2026.³ The company's CEO, Jeff Simmons, 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, the company'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 generally.³

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

References

1. Weekly ER visits for tick bites reach highest level in nearly a decade. News release. Centers for Disease Control and Prevention. 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. Dahl K. 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 Incorporated. 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