In the Northeast and elsewhere throughout the nation, horse owners are becoming increasingly concerned with tick-borne diseases that affect people as well as horses. Ticks in the United States can carry organisms that cause 10 major diseases including Lyme disease, which affects people and animals.
So when the United States Department of Agriculture (USDA) created a novel approach to reducing Lyme disease by reducing tick populations, the agency decided to select the Northeast for its five-year study beginning in 1997.
The approach in design was surprisingly simple but carries the potential for significant benefit.
The “four-poster” is a plastic feeding station with paint rollers attached to its sides. Feed for deer, like corn, is placed in the bin. The paint rollers are coated with anti-tick insecticide; the tick treatment rubs off on the deer as it eats. As the deer grooms, the tick treatment is moved around its body.
Designed by the Agricultural Research Service of the USDA, the four-poster targets the female blacklegged tick that can lay up to 3,000 eggs in a lifetime. The offspring are the ones connected to Lyme disease transmission.
The four-poster was tested in Old Lyme, Ct.; Bedford, N.Y.; Colts Neck, N.J.; and Narragansett, R.I.; as well as the Beltsville Agricultural Research Center, Md.
The goal was the reduction of juvenile ticks (nymphs) by 90 percent; they placed 25 four-posters at each of the five 1,280-acre treatment sites.
The tick treatment is amitraz, which is made to kill ticks and mites without causing harm to beneficial insects. It is approved for use on livestock.
Symptoms of Lyme disease in horses may include fever, lameness and soreness, loss of appetite, listlessness and swollen glands and joints. Some horses have developed laminitis and behavior changes (resistance to work and irritability). If left untreated, Lyme disease can progress into chronic arthritis. Several horse owners have found that they needed to test their horses more than once to get a definitive diagnosis. The disease is treated with antibiotics.
A previous study on the Patuxent Wildlife Research Center, Maryland, found that by using the four-poster after two years, there was 100% reduction of adult ticks and 98% in nymphs.
The theory is that if there are fewer adult ticks, they produce fewer larvas, and, thus, less chances of spreading Lyme and other tick-borne diseases.
Researchers are also testing feeding deer ivermectin, the parasite control medication commonly used to deworm horses.
The study on the four-poster just concluded in August, and investigators will compile their findings to determine the overall impact the “tickicide” had on tick populations; however, according to the USDA, in the first two to three years of the study, nymph counts were reduced by half in several of the test areas.
