MISSISSIPPI STATE -- Dog owners may be surprised to find out that certain ticks can paralyze their beloved pets.

These tick species carry a nerurotoxin that affects the mobility of animals. If the animal is not treated, their limbs may become paralyzed.

Dr. Andy Shores, clinical professor and chief of neurology and neurosurgery in the Department of Clinical Scienes at the Mississippi State University College of Veterniary Medicine, said the toxin affects the function of the motor neurons that control movement. The toxin is usually released five to seven days after the tick attaches.

“The toxin affects the neuromuscular junction, inhibiting the release of acetylcholine from the motor end plate, which is involved in the transmission of nerve impulses in the body,” Shores said. “This basically means that the nerves in the limbs stop working because of the neurotoxin released by the tick, causing the dog to become paralyzed.”

Dog owners should be aware of the signs that signal their pet has been infected with this toxin.

“The signs usually begin in the hind limbs and initially show as a weakness,” Shores said. “This progresses and moves forward. Soon the hind limbs are paralyzed, with absent reflexes.”

Shores said that the condition can become worse, possibly leading to the animal’s death.

“As the condition worsens, the front limbs become involved, and the weakness there is also followed by paralysis and loss of reflex function. In the more severe cases, the respiratory centers can become involved, and the patient will die from inability to breathe.”

Symptoms typically begin to disappear after removal of the tick. Owners must be careful when removing the tick from the dog.

“The mouth parts must be removed,” Shores said. “Ticks carry other diseases, such as Rocky Mountain Spotted Fever and Lyme Disease, which can also infect people. People removing ticks should wear gloves and grasp the tick firmly.”

Dr. Andrea Varela-Stokes, associate professor in the MSU-CVM Departent of Basic Science, said certain tick species in the United States are more commonly associated with tick paralysis.

“Many species of ticks have been associated with tick paralysis, but not all tick bites lead to paralysis, meaning not all members in that species carry the toxin,” Varela-Stokes said.

In the United States, tick paralysis cases are usually associated with Dermacentor ticks, including the American dog tick in the Eastern U.S., as well as the Rocky Mountain wood tick, a Western species.

“Female ticks are the most likely to cause paralysis and may easily stay attached for a week or longer if an animal is not examined routinely,” she said.

Most tick species are found outside, while few can survive indoors for a long period of time.

“Rural areas, forested areas bordering open fields, trails in wooded areas, yards near wooded areas and areas with dense underbrush are all good candidates for most tick species,” Varela-Stokes said. “Some, such as the Brown dog tick, actually do well in kennels, houses, and outside these areas.”

Varela-Stokes said dogs are not the only species at risk.

“In the U.S., tick paralysis is most commonly seen in dogs,” Varela-Stokes said. “Humans in the United States are also at risk; however, this is rare in the Southeast, and more common in the Northwest, where the Rocky Mountain wood tick seems to carry the toxin more often. Birds may also get tick paralysis from another tick species that actually prefers to feed on birds.”

For more information on ticks, publication P2296, “Lyme Disease in Mississippi.”

Contact: Karen Templeton, 662-325-1100