Milder winters, longer exposure seasons and higher deer densities could be responsible for an increased tick population in Tompkins County, which has contributed to a recent spike in Lyme disease found in dogs, experts say.

Lyme disease is caused by the bacterium Borrelia burgdorferi and is transmitted by blacklegged ticks, according to the Centers for Disease Control. Veterinarians in Ithaca have stressed the significance of the disease in dogs, which are much less resistant than other pets, such as cats. When a dog contracts the disease, they will become lethargic, sensitive to touch or experience difficulty breathing.

Paul Curtis, professor of natural resources at Cornell University, said the deer tick population has grown significantly in Tompkins County over the last decade.

Curtis said a Tompkins County Health Department survey revealed that total Tompkins County deer tick submissions increased from 128 in 2007 to 270 in 2008. The number of Lyme disease cases reported in Tompkins County also increased almost 60 percent from 2009 to 2010.

Dr. Sarah Meixell, a veterinarian at Veterinary Care of Ithaca, said she noticed a dramatic increase in tick cases over the past five years.

Meixell said the growing tick population and increase in cases of Lyme disease is likely due to larger populations of the white-tailed deer and the white-footed mouse, two species that are known to carry the disease.

Lyme disease is treatable with an antibiotics, Meixell said, and the majority of dogs generally respond well to treatment.