There are hundreds of species of ticks found worldwide, with as many as 40 of whom are capable of producing paralysis. Most cases of tick paralysis occur in Australia and the United States.
In Australia, Ixodes holocyclus (commonly referred to as paralysis ticks) are the species capable of producing paralysis. These ticks live on the east coast from North Queensland to Northern Victoria. They can be found year round, although are most prevalent in early spring and summer. Their natural hosts are the bandicoot, possum, wallaby and echidna, all of whom have a natural immunity to the tick's toxin. However, paralysis ticks will infest domestic pets, livestock and humans. The preferred habitat of ticks is areas of bush and scrub but can be picked up in other areas such as gardens, parklands and paddocks.
In the United States there are two main species of tick capable of of producing paralysis, Dermacentor variabilis (American dog tick) and Dermacentor andersoni (Rocky Mountain wood tick) with most cases occurring in the Rocky Mountain states, Pacific Northwest and southeastern states between late spring and early summer.
What do paralysis ticks look like?
The appearance varies between species, below are three images of the Ixodes holocyclus tick, found in Australia.
Life Cycle of the paralysis tick
Ticks have 4 stages (moults) of life and require three hosts (either the same or different species) to complete their lifecycle, dropping off their host and re-attaching during each moult. The amount of time this take is dependent on the environmental temperature. The tick is capable of injecting neurotoxin into the cat during the larval, nymph and adult stages, however the largest amount of toxin comes from the adult female.
- Egg - The female tick lays up to 3,000 eggs which hatch within 1-3 months into larva.
- Larva (6 legged) - Around the size of a pinhead, larva are also known as 'seed ticks', tick larva attach to their host within a week of hatching, feeding on the blood of the host for up to a week. Once engorged, they drop off the host onto the ground and undergo a second moult, developing into the nymph.
- Nymph (8 legged) - Now, the size of a match head, the nymph finds a host, feeding for between 4 - 7 days before dropping off and entering the final moult stage.
- Adult (8 legged) - After a week, the adult ticks mate and find a new host to attach to. She finds a host to have one final blood feed, becoming engorged and then falling off the host and laying her eggs and then dies.
What do paralysis ticks do?
As the tick attaches to the cat and borrows its mouthparts into the skin the salivary glands produce a neurotoxin (a toxin which acts on the host's nervous system) which causes paralysis. It is usually the adult female tick who attaches to animals, the male actually parasitises the female tick. The tick is fairly small when it attaches to its host, growing in size as it consumes more blood, a fully engorged tick can be as large as 10mm (1/4 inch). Toxic effects don't occur quickly, as they do with snakes and spider bites, tick poisoning can take hours or even days before symptoms become apparent.
How do paralysis ticks get onto cats?
Stimuli such as heat and movement alert the tick to a potential host. They climb onto vegetation and when an animal passes, it waves its forelegs (known as questing) until it makes contact with the host.
What are the signs of tick poisoning in cats?
Ixodes holocyclus symptoms generally occur between 3-5 days after the tick has attached.
Dermacentor variabilis (American dog tick) and Dermacentor andersoni (Rocky Mountain wood tick), symptoms usually occur within 5-9 days. I holocyclus typically causes more severe symptoms than D. andersoni or D. variabilis.
Early symptoms of tick poisoning include:
- Loss of appetite.
- Vomiting or dry retching.
- Excessive salivation.
- Difficulty swallowing.
- Change to meow (laryngeal paresis).
- Noisy panting.
- Dilated pupils.
As symptoms progress you may notice:
- Limb weakness, starting in the hind legs and progressing to the front legs, appearing wobbly and uncoordinated, falling over. Eventually the cat will be unable to stand at all.
- Laboured breathing.
- Blue tinged gums.
What to do if your cat has been poisoned by a tick?
Try to keep yourself and your cat as calm as possible. Remove food and water as poisoning can prevent the cat from swallowing properly, which can lead to choking. Take him to the veterinarian immediately. The longer you delay taking your cat to a vet, the worse the symptoms will become.
What is the treatment for tick poisoning in cats?
Treatment depends on the severity of the symptoms and is different from case to case. The greater the severity, the more intensive the treatment.
If he is having difficulty breathing, he may be given oxygen.
IV fluids may be given to prevent dehydration.
Your pet will almost certainly be hospitalised and given antiserum to treat I. holocyclus. This serum (the clear part of the blood which contains antibodies) is obtained from dogs who have been made hyperimmune via repeated exposure to paralysis ticks.
Cats affected by D. andersoni or D. variabilis usually improve within 24-72 hours once the tick has been removed.
Cats recovering from tick paralysis need to be kept as stress free as possible.
Recovery is dependent upon severity of symptoms and how quickly treatment commenced. Generally veterinary treatment takes 2 plus days. You will be required to care for your cat for some time after he has been discharged from the hospital also.
Removal of ticks:
It is recommended you wear a pair of latex gloves while removing a tick. Using tweezers or a tick remover (you can purchase these for a few dollars from your veterinarian) firmly grasp the tick's head, as close to the cat's skin as possible. Be extremely careful not to squeeze the body of the tick as this will inject more poison and pathogens into the cat's system. You can also kill the tick while it's still on the cat by using an appropriate insecticide, such as Frontline spray.
Once the tick has been removed, you will notice a crater where the head was attached, this will remain for several weeks.
What products can you use to prevent ticks?
Frontline Plus Top Spot, Frontline spray, Fidos Fre-Itch Rinse Concentrate, Proban tablets or oral liquid.
How do I check for ticks on my cat?
Start from the tip of the nose and using the tips of your fingers, work your way right down to the tail. Ensure you check between the toes, inside the ears (be careful). Go against the grain of the fur. Don't forget to check underneath collars. Ticks will feel like small bumps on the skin.
How do you prevent tick poisoning?
Check your pet thoroughly every day for ticks.
Avoid allowing your cat to wander in the native bushland.
Regularly use insecticides such as the ones listed below if your cat goes outside.
What is Lyme disease and does it affect cats?
Lyme disease is the Borrelia burgdorferi bacteria which is transmitted via tick bites.
Yes, although it has yet to be proven that the paralysis tick passes on Lyme disease to cats in Australia. Lyme disease is passed on via the Deer Tick, also known as the Black Legged tick (Ixodes scapularis) in North America. You cannot catch Lyme disease from your pet, but it is possible for humans to become infected from ticks.
What is Queensland Tick Typhus (Rickettsia australis) and does it affect cats?
Tick Typhus is a bacterial infection caused by the Paralysis Tick. In my research, it doesn't appear to do so, however it does affect humans, again the mode of transmission is via the tick.
Is there a tick vaccine?
No, not currently although the University of Technology, Sydney are working on a tick toxin vaccine.
Can ticks affect humans?
Yes they can. Most tick bites cause few problems to people, however there is a serious danger if the person has a severe allergic reaction to the tick bite or is paralysed by the toxins. Young children are more vulnerable due to their lower body weight. Humans can also catch diseases such as Queensland Tick Typhus from ticks.
Disposing of Ticks
Once removed, save the tick by placing it in a jar of methylated spirit or alcohol so you can take it to your veterinarian for identification.