Pet Parasites in the Northeast: A Regional Overview of Species and Risks

If you live in the Northeastern United States, you can enjoy the changing seasons and a variety of outdoor activities ranging from hiking in the summer and snowshoeing in the winter to leaf-peeping in the fall and birdwatching in the spring. And if you’re a pet parent, we bet your four-legged companion is a big part of how you decide to spend your time. 

But parasites living in the Northeast can create big problems for our dogs and cats. Fleas, ticks, and mosquitoes can spread dangerous diseases and even cause severe illness and death. 

While all of this may seem daunting, rest assured that any risks from these parasites can be avoided by taking precautions and keeping your pet on year-round preventatives.  

Keep reading for a regional guide to heartworm disease, fleas, and ticks in the Northeastern states of New York, Connecticut, New Jersey, Pennsylvania, Massachusetts, Rhode Island, New Hampshire, Vermont, and Maine. 

Heartworm Disease in the Northeast 

Heartworm disease is a serious illness that could lead to lung disease, heart failure, and death if untreated. The disease is transmitted by a mosquito infected with the Dirofilaria immitis parasite biting your pet. The parasite multiplies in the heart, lungs, and blood vessels of the infected animal.

According to Dr. Jennifer Rizzo, the current president of the American Heartworm Society and an emergency veterinarian at Blue Pearl Pet Hospital in Gainesville, Florida, heartworm is spreading north due to the movement of shelter animals from the south to help reduce overcrowding and save countless dogs from euthanasia. 

“While the organizations who help with transport do their best to prevent transmission of heartworms, tests may not turn positive until pets have already arrived at their new homes,” Dr. Rizzo says. 

Although southern states still have the highest number of heartworm cases, according to the Heartworm Incidence Map from the American Heartworm Society, the number of cases is growing in the Northeast. 

“We’ve recently seen increased incidence in New York, Massachusetts, and Connecticut, but essentially every population center has the potential for increased heartworm incidence,” states Dr. Doug Carithers, director of applied research for Boehringer Ingleheim in Duluth, Georgia, who is on the board of the American Heartworm Society. 

Mosquitoes aren’t just relegated to wooded areas, swamps, and backyards. According to Dr. Carithers, these pesky critters also thrive in microclimates near heat-sinks in paved areas, brick buildings, and other heat sources. Therefore, urban areas can be habitats for mosquitoes, too.  

Mosquitoes that transmit heartworm disease to pets in the Northeast are at their peak in the spring, summer and fall months, but the risk of heartworm disease is all year round.  

“Some pet owners might think heartworm is only a risk to their pets during the warmer months,” says Dr. Susan Denault, a New Hampshire-based veterinarian at Banfield Pet Hospital. “However, Banfield’s data underscores the importance of year-round prevention as rates of heartworm diagnosis in pets seen at our hospitals stayed relatively the same throughout all four seasons in 2023.”

Fleas in the Northeast 

In addition to being uncomfortable and irritating, fleas are biting and blood-sucking parasites that cause skin problems and bacterial infections for pets. 

“By the time you start to notice signs of a flea infestation, your pet will already be suffering the effects of them,” says Dr. Denault. “You will already have flea eggs in your carpet and furniture. They live where your pets live, sleep, eat, and play.” 

These black to reddish-brown nuisances can live in your yard, particularly where there is shade and humidity. They also reside in shrubs, tall grasses, and piles of leaves and debris. 

“Fleas can be found during all months of the year, though there is an increase in cases in the warmer months,” says Dr. Lindsay Kendrick, medical director for Veterinary Emergency Group in Boston, Massachusetts.

Both dogs and cats living in the Northeast are susceptible to flea infestations. Pets can get fleas if they spend time outdoors, but humans, rodents, and other pets can bring these parasites indoors. Wild animals found in the Northeast region, like chipmunks, opossums, and raccoons, can carry fleas into your yard and spread them to your pet. 

According to Dr. Alex Blutinger, medical director at the Veterinary Emergency Group in Greenwich, Connecticut, and White Plains, New York, fleas are most common in indoor and outdoor pets who are not getting their regular flea and tick preventatives. 

Ticks in the Northeast 

According to Dr. Denault, ticks are found in most parts of the country but these parasites have expanded their range to Northeastern states in recent years as a result of milder winters due to climate change.  

It’s a common misconception that ticks are only active in the summer. Ticks actually thrive wherever the temperature is above 30 degrees Fahrenheit, with April through October being prime tick season. 

Ticks tend to hitch a ride on your dog after a hike, camping trip, or even walks in grassy or wooded areas. Additionally, “ticks themselves are spread by many different animals, including birds that can transport them long distances,” says Dr. Denault. Apart from deer, other animals that are host to ticks are rodents and mice. Cats who go outdoors get ticks in the same ways our canine companions pick them up.

When bitten by an infected tick, your pet potentially gets exposed to a number of serious diseases. “In our area, several types of ticks can transmit diseases to dogs,” says Dr. Kendrick. “These include blacklegged ticks, also known as deer ticks, which can carry the bacteria that cause Lyme disease, anaplasmosis, and ehrlichiosis.” 

Lyme disease gets its name from the town of Lyme, Connecticut. Dr. Denault states that Lyme disease has been identified across the country, but its highest prevalence is in the Northeast and the Great Lakes regions. Climate change is also increasing cases of babesiosis, an emerging infection which causes anemia, with severe disease leading to death. 

Below are common tick-borne diseases impacting pets in the Northeast and the tick species that cause them: 

• Lyme disease – deer tick/blacklegged tick 
• Anaplasmosis – deer tick/blacklegged tick 
• Babesiosis – deer tick/blacklegged tick 
• Ehrlichiosis – lone star tick, brown dog tick
• Rocky Mountain spotted fever – American dog tick
• Tularemia – American dog tick, lone star tick 

Another tick-related condition to keep an eye out for is tick paralysis. This isn’t an infectious disease. It’s caused in dogs by a reaction to tick saliva. Ticks in the Northeast that cause tick paralysis include the deer tick/blacklegged tick, lone star tick, and American dog tick.

Ticks in New York 

Ticks in New York state can be found from the shores of Montauk to the forests of Upstate and anywhere there are wooded and grassy areas. They can even live in backyards. 

According to Dr. Blutinger, animals that spend time outside or in wooded areas are at a particularly higher risk of infection and should be protected through monthly preventatives. “Ticks tend to thrive most in warm, humid weather, but they pose a risk as long as the temperature is above freezing.” In New York, they are mostly found in understory vegetation, trail edge vegetation, and wooded and grassy areas. 

Types of Ticks in New York Dangerous for Pets

• American dog tick (Dermacentor variabilis)
• Lone star tick (Amblyomma americanum)
• Blacklegged tick/deer tick (Ixodes scapularis)

Tick-Borne Diseases Diagnosed in New York 

• Lyme disease
• Ehrlichiosis
• Anaplasmosis 
• Babesiosis
• Rocky Mountain spotted fever (rare)

Ticks in Connecticut 

Ticks in Connecticut are abundant in forests, their surrounding areas, and in tall grassy brush bordering woodlands. The deer tick, as its name indicates, uses deer as hosts. Increases in white-tailed deer population in the state is leading to the growth of the tick population. 

Among the types of ticks in Connecticut listed below, non-native Asian longhorned ticks were first found in Connecticut in 2018. They are known to cause serious illness and they typically are seen in the thousands. According to the Connecticut Agricultural Experiment Station, ticks in Connecticut are living year round due to climate change.  

Types of Ticks in Connecticut Dangerous for Pets 

• American dog tick (Dermacentor variabilis) 
• Blacklegged tick/deer tick (Ixodes scapularis)
• Lone star tick (Amblyomma americanum)
• Asian longhorned tick (Haemaphysalis longicornis) 

Tick-Borne Diseases Diagnosed in Connecticut 

• Lyme disease
• Babesiosis
• Anaplasmosis
• Ehrlichiosis

Ticks in New Jersey

According to New Jersey Fish and Wildlife, there are several types of ticks in New Jersey and they pose a threat to outdoor enthusiasts, anglers, birders, and others enjoying nature. The Garden State’s landscape ranges from the Southeastern coastal plain to the Kittatinny Mountains in the Northwest, with major rivers like the Delaware and Raritan Rivers running through it, where people and their pets can enjoy the great outdoors.  

The Asian longhorned tick, native to East Asia, was first discovered in 2017 on a sheep in New Jersey and the species spread to other states by 2020. This invasive tick appears in the thousands and can cause death to animals due to blood loss. One tick can produce up to 2000 eggs, and they tend to infest farm animals, horses, raccoons, opossums, and dogs in Northeastern states.   

Types of Ticks in New Jersey Dangerous for Pets

• American dog tick (Dermacentor variabilis)
• Asian longhorned tick (Haemaphysalis longicornis)
• Blacklegged tick/deer tick (Ixodes scapularis)
• Lone star tick (Amblyomma americanum)

Tick-Borne Diseases Diagnosed in New Jersey 

• Lyme disease 
• Anaplasmosis 
• Babesiosis 
• Ehrlichiosis
• Rocky Mountain spotted fever (rare) 

Ticks in Pennsylvania 

The Keystone State is an outdoor-lover’s paradise, with rolling hills and rivers like the Delaware and Lehigh. The Appalachian Mountains run from the south central area to the Northeastern part of the state and the Allegheny Mountains lie to the west. This also means many opportunities for ticks to thrive and seek hosts, especially in the warmer months. 

There are several types of ticks in Pennsylvania. Out of 900 species of ticks worldwide, you can find 25 of them in Pennsylvania. The most prevalent tick-borne disease seen in pets in Pennsylvania is Lyme disease. 

Types of Ticks in Pennsylvania Dangerous for Pets 

• Blacklegged tick/deer tick (Ixodes scapularis)
• American dog tick (Dermacentor variabilis)
• Lone star tick (Amblyomma americanum)
• Asian longhorned tick (Haemaphysalis longicornis)

Tick-Borne Diseases Diagnosed in Pennsylvania 

• Lyme disease
• Babesiosis
• Ehrlichiosis
• Rocky Mountain spotted fever (rare)

Ticks in Massachusetts 

The most common ticks found in yards and in wooded and forested areas of the state are deer ticks and dog ticks. Lone star ticks are found in some parts as well. 

Types of Ticks in Massachusetts Dangerous for Pets

• Blacklegged tick/deer tick (Ixodes scapularis)
• American dog tick (Dermacentor variabilis)
• Lone star tick (Amblyomma americanum)

Tick-Borne Diseases Diagnosed in Massachusetts 

• Lyme disease
• Babesiosis
• Anaplasmosis
• Ehrlichiosis
• Rocky Mountain spotted fever (rare) 

Ticks in Rhode Island 

Rhode Island is known for its Gilded Age mansions and spectacular seaside scenery, but the smallest state in the country is no stranger to ticks, which are found in thick brush and tall grassy areas. The deer tick/blacklegged tick is the most common tick in Rhode Island causing issues for pets. Lone star ticks have also spread northward and expanded into the state. 

Types of Ticks in Rhode Island Dangerous for Pets 

• Blacklegged tick/deer tick (Ixodes scapularis)
• American dog tick (Dermacentor variabilis)
• Lone star tick (Amblyomma americanum)

Tick-Borne Diseases Diagnosed in Rhode Island

• Lyme disease 
• Babesiosis 
• Anaplasmosis
• Ehrlichiosis
• Rocky Mountain spotted fever (rare) 

Ticks in New Hampshire 

With its majestic mountains and beautiful lakes, the Granite State draws people to its great outdoors. Tick Free New Hampshire claims the state has had the highest incidences of Lyme disease in the country in recent years, putting both pets and people at risk of getting infected by these pesky parasites.  

Types of Ticks in New Hampshire Dangerous for Pets 

• Blacklegged tick/deer tick (Ixodes scapularis)
• American dog tick (Dermacentor variabilis)
• Brown dog tick (Rhipicephalus sanguineus)

Tick-Borne Diseases Diagnosed in New Hampshire 

• Lyme disease  
• Anaplasmosis
• Babesiosis

Ticks in Vermont 

Among the 15 types of ticks in Vermont, the blacklegged tick is the most abundant and is responsible for the majority of tick-borne illnesses reported. According to a 2021 study by the Vermont Department of Health, 92 percent of the ticks collected were blacklegged ticks and over half of them were infected with the pathogen Borrelia burgdorferi that causes Lyme disease. 

Types of Ticks in Vermont Dangerous for Pets

• Blacklegged tick/deer tick (Ixodes scapularis)
• American dog tick (Dermacentor variabilis)
• Brown dog tick (Rhipicephalus sanguineus)
• Lone star tick (Amblyomma americanum)

Tick-Borne Diseases Diagnosed in Vermont 

• Lyme disease
• Anaplasmosis
• Babesiosis
• Ehrlichiosis

Ticks in Maine 

With temperatures rising, more and more adventurers are taking advantage of Maine’s rocky coastline and nature-based activities. But humans and their pets are also getting exposed to tick-borne diseases as deer (and the ticks that go with them) are migrating northbound. In the last two decades, the incidence of tick-borne diseases in the state – including Lyme disease, anaplasmosis, and babesiosis – has increased dramatically. On average, 1 out of every 8 dogs that are screened for Lyme disease in Maine tests positive. 

Types of Ticks in Maine Dangerous for Pets

• American dog tick (Dermacentor variabilis)
• Brown dog tick (Rhipicephalus sanguineus) 
• Lone star tick (Amblyomma americanum)
• Blacklegged tick/deer tick (Ixodes scapularis) 

Tick-Borne Diseases Diagnosed in Maine  

• Lyme disease
• Anaplasmosis
• Babesiosis
• Ehrlichiosis
• Rocky Mountain spotted fever (rare)

Living in the Northeast: Protecting Your Pet From Parasites

Although fleas, ticks, and mosquitoes that carry heartworm disease are a real risk for pets and people living in the Northeastern U.S., there are several things you can do to keep yourself and your pet protected. 

See below for tips and information on how you can protect your pets from fleas, ticks, and heartworms. 

Heartworm Preventative Care

Put your pet on a year-round heartworm preventative. Get a prescription from your veterinarian for heartworm prevention, recommends Dr. Carithers. It’s important to prevent the disease, because treating a heartworm infection in dogs is difficult and costly. “Permanent damage often occurs in the lungs of the dog, even before the dog tests positive for a heartworm infection,” he adds.

Practice mosquito management. Control the mosquito population in your backyard to reduce the risk of heartworm disease. Dr. Carithers notes that the state of Florida focused on mosquito abatement to ensure a pleasant experience for tourists and, as a result, the state has the lowest heartworm incidence in all of the southern states. 

Limit your pet’s exposure to mosquitoes. According to Dr. Rizzo, minimizing outdoor activities during peak mosquito feedings (dusk and dawn) and avoiding mosquito habitats, including standing water, will greatly reduce the risk of heartworm.

Try a mosquito repellant. Pet owners can also use topical FDA- or EPA-approved mosquito repellents and insecticides for pets to provide additional protection. “While using these products can reduce exposure to mosquitoes carrying heartworms, they should be used in conjunction with heartworm preventives, not instead of them,” Dr. Rizzo adds.

Don’t skip heartworm testing. If you’ve adopted a dog from the South, get a blood test to ensure your pet doesn’t have heartworm disease. Typically, rescues do their test before adopting the animal, but testing with your own veterinarian after adoption can help prevent the spread of heartworm disease in your area. Veterinarians recommend up-to-date heartworm testing once per year, even if pets are on a heartworm preventative. 

Keep your cats safe. Despite the prevalence of heartworm disease in dogs, cats can get infected with heartworms too and need to be on a heartworm preventative. “There is currently no safe treatment to remove or kill adult heartworms in cats,” says Dr. Denault. “Infected cats can only be treated supportively and symptomatically.” 

Fleas and Ticks Preventative Care 

Provide pets with year-round flea and tick prevention. Keeping your pets free of fleas and safe from tick-borne diseases is easy by administering preventatives. Many products approved by the FDA can protect dogs and cats against fleas, ticks, and other parasites like intestinal worms with one medication. Make sure to follow the manufacturer’s instructions and your veterinarian’s recommendations for dosing and use to ensure the products are safe and effective.     

Always check for ticks. Check your pets for ticks if they’ve been outside in wooded or grassy areas and remove any ticks you find quickly to reduce the risk of transmission, recommends Dr. Denault. “If you remove a tick from your pet or have reason to believe your pet may have been exposed to Lyme bacteria, watch for and contact your veterinarian immediately if you notice any signs in the weeks that follow.”

Practice good grooming. Brush your pet regularly and use a flea comb, which can help find and remove fleas. You can also consider using flea and tick preventatives in the form of shampoos, rinses, and sprays that are approved for use with the EPA or FDA, recommends Dr. Denault. Just remember – these should be used in conjunction with a year-round oral or topical flea and tick preventative.

Ask your veterinarian about the Lyme vaccine. If you enjoy going hiking with your dog regularly, speak with your veterinarian about getting a Lyme vaccine to prevent the spread of Lyme bacteria from ticks to your dog.

Keep covered when in tick-prone areas. When out hiking or spending a lot of time outdoors, protect yourself by wearing light colored clothing (so ticks are visible), long-sleeved shirts, and long pants. You can also apply a tick repellent to exposed skin and walk in the center of paths to avoid grassy areas where ticks live.