A Surge in Heartworm Disease and Tick-Borne Diseases

Are Heartworm Cases on the Rise?

WVH is currently treating 3 dogs in our practice for heartworm disease. Many of the positive cases we see each year are cases where prevention was given Spring, Summer and Fall, but not over the Winter.

The American Heartworm Society (AHS) has just released a new Heartworm Incidence Map, using data collected from veterinary practices and shelters across the U.S. The states with the highest density of heartworm cases continue to be in and adjacent to the lower Mississippi Delta (Mississippi, Louisiana, Texas, Alabama, and Arkansas), but survey results also indicate a troubling trend: that heartworm cases have continued to edge upward both in states with the highest heartworm rates and in regions that historically have enjoyed low rates. Meanwhile, roughly half of veterinarians from participating practices and shelters said that heartworm rates have stayed about the same (53%) or increased (29%) rather than decreased (17%)

Research from the Companion Animal Parasite Council (CAPC) indicates seroprevalence of Lyme disease in dogs is not only increasing in the Northeast, where it is considered endemic, but also spreading into areas that were previously thought to not be at risk for this serious, zoonotic tick-borne disease. Specifically, exposure in dogs to B. burgdorferi is rising in states not traditionally considered to be areas of high Lyme risk. Significant increases in the percentage of dogs testing positive for exposure have also been seen in areas that have not yet reported significant human incidence. These findings suggest canine Lyme prevalence could serve as an early warning system for changes in human risk of exposure. Areas where human risk may be increasing include regions in Illinois, Iowa, Michigan, North Dakota, Ohio, and Tennessee. According to the CDC, Lyme disease is the most common vector-borne disease for humans in the United States. Lyme disease is caused by the bacterium Borrelia burgdorferi and rarely, Borrelia mayonii. It is transmitted to humans through the bite of infected blacklegged ticks. Disease transmission can occur when pets bring ticks into the home environment. Steps to prevent Lyme disease include having your pets on monthly prevention year round, using insect repellent, removing ticks promptly, applying pesticides, and reducing tick habitat. The ticks that transmit Lyme disease can occasionally transmit other tickborne diseases as well. Some types of ticks can be active if the temperature is above 45 degrees Fahrenheit and the ground is not wet or icy. The American dog tick and lone star tick are not as active during the fall and winter months. However, Blacklegged ticks, which carry Lyme disease, remain active as long as the temperature is above freezing. The adults look for food right around the first frost. Additionally, the winter tick, which hatches in late summer as temperatures begin to decrease, is active during cooler months. This tick is typically found on moose, and sometimes deer, in the Northeastern part of the country. These ticks are different from other species, because they will spend their entire lives on one host. Winter tick eggs hatch on the ground in August and September. Larvae seek out a host between September and November. Those that find a host will overwinter on it, holding onto its hair when they are not feeding. Those that cannot find a host will likely die. Females will remain on a host until the end of winter or start of spring. Then they drop into the leaf litter, where they will lay up to 3,000 eggs before dying.

So, are there ticks in the winter? Yes, there are. Most of them are not a threat to you or your pets, but some can be. You should keep an eye out for ticks even when it's cold outside. 

Visit our online pharmacy to refill your pet’s prevention!