• Posted August 25, 2023

Shelter Dogs Vulnerable to Diseases Spread by Ticks, Mosquitoes

Warming temperatures may be bringing a new risk for shelter dogs: the spread of tick- and mosquito-borne disease in a broader geographic area, according to a new study.

Bites from these pests can cause serious illness in dogs, including heartworm and Lyme disease.

The study, on shelter dogs in the eastern United States, shows that they may experience the brunt of warmer weather, but these diseases can be prevented with medication.

“This study shows us how important those preventive medications are,” said lead author Corinna Hazelrig, a current doctoral student at the University of Georgia College of Veterinary Medicine.

"Preventatives can be expensive, and some pet owners may not want to or be able to invest in them. However, these pathogens are common throughout the eastern United States, and the best management strategy for your pet's health is to use preventive medications on a regular basis," she said in a university news release.

Researchers analyzed blood samples from 3,750 dogs from animal shelters in 19 states across the eastern United States to determine the prevalence of heartworm and three types of tick-borne bacteria.

More than 1 in 10 of the dogs were infected with heartworm.

More than 8% of the dogs had been exposed to the bacteria that causes Lyme disease.

Another 10% were infected with bacteria that cause anaplasmosis or ehrlichiosis, two less well-known tick-borne diseases.

Nearly 5% of the dogs were infected with multiple diseases.

In order to receive the preventative medications, dogs need access to veterinary care. Many neglected or stray animals taken to shelters have not been given these preventive medications for a long time, if ever.

The study pointed out that heartworm infections may be treatable with medication and or surgery, but that's expensive. Many long-term infections are difficult to treat and may be fatal. All of the tick-borne bacteria seen in the study require antibiotics to treat the infection.

Heartworm can damage the heart, lungs and other arteries if left untreated. Lyme disease can cause loss of appetite, fatigue, lameness and kidney damage.

“People in the Northeastern U.S. don't think heartworm is in their region, and people in the Southeastern U.S. don't think Lyme disease is in their region,” Hazelrig said. “However, we detected heartworm in Maine, and we detected exposure to the causative agent of Lyme disease in Virginia. The change in our climate is allowing the geographic range of ticks and mosquitoes to expand."

Study findings were published recently in the journal Parasites & Vectors.

The increasing presence of these disease-carrying ticks and mosquitoes should be concerning to even people without pets, who can also suffer illness from the tick-borne diseases. More than 30,000 confirmed cases of Lyme disease are reported each year, according to the U.S. Centers for Disease Control and Prevention, a number that's likely significantly underestimated.

A UGA study in collaboration with Clemson University in South Carolina found that areas where more dogs are exposed to the bacteria that causes Lyme disease have higher rates of human infection as well.

"These data help us understand the distribution of these pathogens, how their distributions are changing and where we may expect human infections to occur," said Michael Yabsley, an author on both studies and a professor in UGA's Warnell School of Forestry and Natural Resources and the College of Veterinary Medicine.

More information

The U.S. National Library of Medicine has more on Lyme disease.

SOURCE: University of Georgia, news release, Aug. 22, 2023