The calendar
Year round parasite prevention in the South
Short winters, standing water, mosquitoes active most of the year: why the Southern prevention calendar has no month off, and what runs through it.
In the South, parasite prevention has no month off. Short winters, standing water and mosquitoes active most of the year keep the pressure continuous, and the calendar that manages it runs January to December without a dead season. That is not a slogan; it is what the region's own disease maps show, year after year, with their publishers named.
Two numbers frame everything below, both carrying their source and their year. The Delta sits in the highest heartworm incidence band in the country, per the 2025 survey of the American Heartworm Society, published in April 2026. And the tick borne disease the maps track beside it reads high across the Southeast and is moving north, per the county maps of the Companion Animal Parasite Council. The unfolding of the first number is heartworm in the Delta.
Why the calendar never closes
In a colder state, prevention used to pause for winter on the theory that the vectors slept. The Gulf South barely has that winter: hard freezes are brief and rare, standing water holds warmth, and a mosquito season that would end in October elsewhere stretches deep into what the calendar calls winter. A prevention schedule with a hole in it is built for a climate this region does not have. The decision on product, dose and timing belongs to the treating veterinarian; the season that makes the question continuous belongs to the map.
The four families the calendar manages
Heartworm, spread by mosquito, is the founding fact of Southern dog keeping, and the region leads the country in it. Intestinal parasites, hookworm chief among them, follow the same warmth and the same standing water, and the Council's county maps carry their load too. Fleas never froze out to begin with. Ticks carry the diseases the maps track as a band across the Southeast: high where the humidity lives, and extending north of their old range. Four families, one climate behind all of them, and one conversation with the veterinarian that covers the set.
The test and the lapse
The annual heartworm test is the frame the whole calendar hangs on, and the conversation before restarting prevention after a lapse is part of the frame: a dog off prevention for a stretch is tested before the schedule resumes, on the timing the treating veterinarian sets, because giving the preventive to a dog already carrying the worms is its own medical question. Neither the test nor the answer is a web page's to prescribe. What a web page can do is say plainly: keep the test date, notice the lapse, and make the call rather than let the gap ride.
The year as the South writes it
| Stretch of the year | What the season carries | What the calendar holds to |
|---|---|---|
| Late winter | The brief freeze that never quite arrives | The annual test and the year's plan, set with the veterinarian |
| Spring | Mosquito pressure building, ticks waking early | The refill conversation before the season peaks |
| Summer | Peak mosquito months, heat stacking on everything | The schedule kept, the water kept, the yard walked |
| Early fall | The long warm tail, ticks still working | No wind down; the maps stay high into October |
| Late fall | Standing water still warm enough | The question asked again before winter, not after it |
When the clinic is an hour and a half away
Distance changes readiness, not the calendar. In much of the region the nearest emergency clinic can be an hour and a half of driving, which converts a small preparation into a large outcome: the file with the test dates and the vaccination record, the refills requested before they run out, and the route to the after hours door known before the night it is needed. The emergency that distance punishes worst is the one prevention was quietly managing all along, which is the strongest argument for the calendar having no hole in it.
The kit and the file
What the year round owner keeps current
The preventive half of dog keeping in the South, in one list.
- The annual test date on the calendar, not in the memory.
- The prevention in hand before the current supply runs out.
- The standing water in the yard walked and dumped after every rain.
- The veterinary file, test dates and prescriptions, in one folder.
- The route and the after hours number for the nearest emergency clinic.
- The county prevalence map checked once a season, with its year noted.
Keeping this page honest
Every health statement above carries its publisher: the incidence survey of the American Heartworm Society, 2025 edition published April 2026, and the county prevalence maps of the Companion Animal Parasite Council. No product, dose or schedule is named or implied, because those are decided with the treating veterinarian, who can see the dog and read its file. What prevention does not cover, heat and venom, is the next page: heatstroke and snakebite.