As Spring weather begins to hint at summertime, pet owners begin to consider protecting their pets and family from parasites. Actually what most people don’t realize that fleas, ticks and mosquitoes are active in every state—and not just during the warmer months. Veterinarians and pet healthcare companies are currently issuing a nationwide reminder that year-round prevention is the best way to keep pets and families safe. Professionals tell us that “Parasites don’t follow a calendar”; Vets report that they “see dogs and cats dealing with parasite-related illnesses throughout the year, even if they don’t go outside much. Sometimes, it just takes one little mosquito slipping in through an open door or a flea hitching a ride on someone’s pant leg for your furry friend to end up with more than just an itch.”
Data from 2024 from the Companion Animal Parasite Council, shows that some U.S. states had higher-than-average rates of parasite-borne illnesses in dogs and cats. Here are some of the details from their current report:
- Heartworm disease (dogs): Carried by mosquitoes, heartworm can affect a dog’s heart and lungs. Some dogs exhibit signs such as coughing, shortness of breath, fatigue after moderate activity, or weight loss, while others may not show symptoms until the disease is more advanced. Fortunately, it’s very preventable with veterinarian-prescribed preventatives.
- Mississippi has the highest infection rate, with 1 in 15 dogs testing positive.
- Louisiana, Alabama and Arkansas follow closely at 1 in 30.
- Heartworm-positive cases have also increased in Texas, South Carolina and Georgia.
- Heartworm disease (cats): Cats can also get heartworm, even if they never go outside. A single mosquito bite is all it takes. Symptoms may include coughing, vomiting or difficulty breathing, but some cats show no signs at all.
- Approximately 1 in 500 cats nationwide test positive for heartworms each year.
- Heartworm rates are higher in Texas, Mississippi, Alabama and Louisiana, where 1 in 200 cats tested positive.
- Lyme disease: Lyme disease is the most common tick-borne illness in dogs. It may cause joint stiffness, lethargy, and loss of appetite. If caught early, it’s manageable with treatment.
- West Virginia had the highest infection rate, with 1 in 6 dogs testing positive.
- Vermont, Maine and Connecticut are also high-risk states, with 1 in 8 dogs testing positive.
- Pennsylvania, Massachusetts and New Hampshire follow closely, with 1 in 10 dogs testing positive.
- Anaplasmosis: Spread by ticks, anaplasmosis can affect dogs, cats and humans. In pets, it can cause fever, lethargy, joint pain, and loss of appetite, while in humans, symptoms resemble those of the flu. It’s typically treated with antibiotics.
- The highest rates were found in Maine and Vermont, with 1 in 3 dogs testing positive
- Connecticut, New Hampshire and Massachusetts followed at 1 in 4 dogs testing positive.
- Ehrlichiosis: Another tick-borne illness, ehrlichiosis may cause symptoms in pets such as low energy, joint pain or changes in appetite. In most cases, it can be treated, especially when caught early.
- Arkansas had the highest number of cases, with 1 in 6 dogs testing positive
- Missouri (1 in 10) and Oklahoma (1 in 11) followed.
Fleas, Ticks and Mosquitoes Don’t Take a Season Off
While many people believe parasite problems disappear in winter, that’s not the case. Parasites are resilient and can stick around in warm homes or mild outdoor climates.
A tick can survive for more than 200 days without food or water, and fleas can continue to multiply even in your living room. That’s why year-round prevention makes a big difference.
Approximately 1 in 7 dogs and 1 in 4 cats are affected by fleas, which can lead to itchy skin, tapeworm infections, or other health issues.
Protecting Pets and Families   Â
Veterinarian-prescribed preventatives are the most effective way to protect pets from parasites and their associated diseases.
Here is a link to the 2025 Parasite Maps so you can check on the U.S. states that had higher-than-average rates of parasite-borne illnesses in dogs and cats. These can show you the area of the state you live in or check on a place you plan on visiting this summer.
Companion Animal Prevalence Parasite Maps
There is also much more information that may be helpful.