Tick Paralysis in Cats

Tick paralysis in cats primarily occurs in Australia, with only rare reports in domestic cats elsewhere in the world.

Tick paralysis is most common in the spring and early summer, when female ticks are most active.

When tick paralysis does occur, it presents a life-threatening emergency. A cat showing weakness in the limbs, paralysis, difficulty swallowing, or difficulty breathing - even without known exposure to ticks - needs immediate medical attention.

Australian veterinarians have developed a four-stage classification system for cases of tick paralysis. As the condition progresses, affected cats move through the following stages:

• Stage 1: the muscles are weak but the cat can still walk and stand
• Stage 2: the cat cannot walk but can stand
• Stage 3: the cat cannot stand but can still sit up
• Stage 4: the cat cannot sit up and lays flat

Animals in Stage 3 and 4 are considered to have a poor prognosis.

Some cats show only respiratory symptoms and no obvious motor deficits.

Outdoor cats are at highest risk of exposure to ticks. Cats who live with other outdoor animals are also at higher risk, but ticks may enter the home and bite indoor cats as well.

Tick paralysis is caused by a neurotoxin found in the saliva of certain species of ticks which are primarily found in Australia. While feeding on its host, the tick delivers the neurotoxin into the lymphatic system where it spreads throughout the body. The toxin affects muscle contraction, including the muscles involved in breathing.

Symptoms of tick paralysis usually appear 3-5 days after tick attachment, and worsen rapidly over the following 24-48 hours. In some environmental conditions, like cooler weather, it may take up to 14 days for symptoms to start.

In Australia where tick paralysis is most common, diagnosis is often presumptive and based only on presentation of typical symptoms and exposure to tick habitat.

Routine tests like blood work and diagnostic imaging may provide more information about a cat’s condition and prognosis, but these are not always necessary.

Ticks must be removed for the cat to recover from tick paralysis. Clipping the cat’s coat may be necessary to ensure all ticks are removed. External parasite control agents are used to kill any remaining ticks.

In some cases, the tick(s) may have already dropped off of the cat, making diagnosis difficult. Even if a tick is not found, treatment must be administered promptly.

Tick antitoxin is administered, allowing the neurotoxin to be expelled from the body without doing further damage. Tick antitoxin can have side effects, so it may not be administered to cats with mild symptoms that aren’t rapidly getting worse. Once the need for antitoxin is established, additional treatment to address the symptoms may include:

• Physical stabilization and support of the cat while waiting for the muscles to recover
• Supplemental oxygen and/or mechanical ventilation for cats who cannot breathe adequately
• Intensive nursing care to address hydration, nutrition, and elimination of body wastes (depending on the severity of paralysis)
• In-clinic monitoring: Symptoms may worsen significantly before recovery, so close monitoring is essential to prevent complications
• Cats with tick paralysis experiencing significant stress and anxiety may benefit from anti-anxiety medication as cats suffering from tick paralysis are particularly susceptible to stress-induced airway obstruction

Feline tick paralysis resulting from tick bites generally has a good prognosis with appropriate early treatment. Most cats recover with no long-term effects. Cats that are severely affected with profound weakness, a low body temperature, or those who require mechanical ventilation are less likely to recover. The mortality rate, even with antitoxin treatment, is approximately 2%.

Tick paralysis is not contagious, but ticks can transmit the neurotoxin to any animal they are attached to, including humans.

Tick-borne illnesses are effectively prevented by year round veterinary preventative external parasite control. Always consult a vet before selecting external parasite control as some products on the market are not proven to be safe and effective for use.

Tick paralysis is reported in approximately 10 000 domestic animals (including cats) per year in Australia. Australian cats who go outdoors, particularly in the spring and early summer, are most at risk of tick paralysis. Outside of Australia, tick paralysis is not commonly reported.

• Removal of ticks
• Application of an external parasite control product
• Tick antitoxin (where indicated)
• Sedation
• Supportive care
• Mechanical ventilation (where indicated)