Tick Paralysis in Dogs

Ticks are parasites that feed on the blood of mammals. They are found worldwide all year round.

Symptoms of tick paralysis typically appear two to nine days after a tick bites and will worsen if the tick is not removed. Symptoms initially appear mild, as weakness limited to the rear of the body. As the disease progresses, symptoms move in an ascending fashion toward the front of the body and become more severe as weakness develops into full-fledged paralysis.

While rare, tick paralysis in dogs can be life-threatening. Dogs showing symptoms of paralysis need emergency medical care, regardless of any known tick exposure. Rapid identification and removal of all ticks on a dog with symptoms of tick paralysis is critical for recovery.

All dogs are at risk of exposure to ticks. The risk of exposure to tick paralysis depends on what type of ticks are endemic in a dog’s geographic region. In North America, tick paralysis is most prevalent in the southeastern and northwestern regions. Most cases of paralysis occur from May to June, but tick paralysis has been reported year-round.

Dogs who are not on tick-prevention medication have a higher risk, as do dogs who spend time where ticks live (woodlands and grassy areas), even if they do take medication. There is no difference in reported cases of tick paralysis based on age, breed, or sex.

Each dog reacts to the stress of the toxins differently. Puppies, older dogs, small dogs, and dogs with other illnesses (comorbidities) tend to have more severe cases of tick paralysis.

Tick paralysis is caused by the bites of certain species of ticks. In North America there are six species whose females are thought to carry the neurotoxin:

• Dermacentor andersoni (Rocky Mountain wood tick)
• Dermacentor variabilis (American dog tick)
• Amblyomma americanum (lone star tick)
• Amblyomma maculatum (Gulf Coast tick)
• Ixodes scapularis (black-legged tick or deer tick)
• Ixodes pacificus (western black-legged tick)

The most prevalent early symptom of tick paralysis is weakness in the hind legs. This progresses toward the front legs, affecting the whole body as it moves forward.

Initial assessment involves physical examination to determine if there are any ticks attached to the skin.

Even if no ticks are found, the presence of a tick bite on the skin can suggest that a dog’s sudden paralysis is the result of a tick exposure. Tick bites have a characteristic crater-like sore with raised, red edges surrounded by scabby debris and a small dark hole at the center.

If the symptoms lessen within a couple of hours following the removal of ticks and/or use of an acaricide, a diagnosis of tick paralysis is confirmed.

The first priority for a dog with tick paralysis is to find and remove all ticks. In reported cases, 10% of dogs have more than one tick, so a thorough examination is critical. To ensure all ticks are found, shaving long or matted hair is often necessary. Sedation may be required to facilitate shaving and reduce stress. Acaricides (pesticides that specifically target ticks) are used in an effort to kill any remaining ticks that escape detection.

Hospitalization is necessary for dogs with severe symptoms.

The use of tick antiserum (canine tick hyperimmune serum) to neutralize the salivary toxin shows promise as a treatment.

90 to 95% of dogs recover from tick paralysis. Afflicted dogs are expected to improve within hours of having all the ticks removed or killed. Most symptoms resolve within one to three days. Muscle strength may not fully return for months, but most dogs recover completely when treated appropriately. Exercise restriction is advised for 1-2 months for dogs recovering from tick paralysis.

If untreated, the dog can die from paralysis of the respiratory muscles.

Tick paralysis itself is not contagious. No vaccine is available for tick paralysis. Tick antiserum (canine tick hyperimmune serum) shows promise as a form of treatment for tick paralysis and its investigation is ongoing.

Tick paralysis can only result from direct exposure to toxic tick saliva. Almost all warm-blooded land animals can be affected by tick paralysis, including humans. The best way to prevent tick paralysis is to use year-round tick-control products. Prescription preventatives are the safest and most effective options. Always consult a veterinarian before choosing external parasite control. Many available products are toxic to pets, especially cats.

To minimize risk, check for ticks any time dogs have been in an area where ticks are prevalent.

Tick paralysis is not commonly reported in dogs.

• Removal of ticks
• Acaricidal treatment
• IV fluids
• Assistance with eating
• Parenteral nutrition
• Bladder and bowel assistance
• Supplemental oxygen
• Mechanical ventilation