Tick Paralysis

Tick paralysis in Australia is caused by the Ixodes holocyclus tick, a blue/grey coloured parasite. Dogs and cats are affected, and the condition is usually fatal if left untreated. It is assumed to be due to a protein neurotoxin produced by ticks and introduced during biting. 

The circulating neurotoxin interferes with acetylcholine release at neuromuscular junctions leading to an ascending paralysis. Toxicity is mainly associated with female ixodid ticks and incidence of the disease is related to the latter’s activity in the spring and early summer.
The incubation period is 5 - 9 days, i.e., from the time of introduction of toxin until signs appear.

Signs

Body temperature regulation is affected and depending on outside temperatures the animal may have a subnormal temperature or be overheated. Initially there are discomfort and often vomiting and trouble swallowing followed by abnormal hindlimb reflexes, unsteady gait, incoordination and weakness with ascending paralysis (starting with the hind legs and moving forwards to the head). Animals remain conscious and can see and feel normally. Soon the animal is unable to move, breathing is difficult and death may ensue in several hours if ticks are not removed and the animal treated with specific antiserum. If ticks are removed in time recovery takes place within 1 - 3 days.

Treatment and Control

• Prompt removal of ticks
• Specific antiserum
• Supportive therapy including intravenous fluids (as nothing can be given by mouth until paralsis is cured), temperature control, oxygen therapy and supervision
• Measures should be directed toward reducing exposure to ticks and to their removal when present. Preventic flea collars, advantix and frontline are recommended for dogs.  For cats spray frontline and/or proban tablets are recommended

Public Health Significance

Humans are susceptible to tick paralysis initiated by tick bites; however, animals with tick paralysis cannot transmit the disease to humans.