Paralysis Ticks

Overview:

Ticks are blood sucking ectoparasites (a parasite that lives on the exterior of an animal). There are hundreds of species of ticks worldwide. Australia has around 70 species of ticks.

Paralysis ticks (Ixodes holocyclus) affect dogs in Australia. They live on the east coast from North Queensland to Northern Victoria. In northern parts of Australia, ticks can be found all year around. In the cooler southern areas, tick season is generally from spring through to late autumn. 

What do paralysis ticks look like?

(click to enlarge)

Tick Mouth Parts

Life Cycle of the Paralysis Tick

Ticks have 4 stages of life... 

1) Egg

2) Larva (6 legged)

3) Nymph (8 legged)

4) Adult (8 legged)

What do Paralysis Ticks do?

The tick attaches to the dog & borrows it's mouthparts into the skin. It sucks the blood & injects a neurotoxin called Holocyclotoxin, which causes paralysis.  It is usually the female tick who attaches to animals, the male actually parasitises the female tick. The tick is fairly small when it attaches to it's host, growing in size as it consumes more blood. Illness doesn't occur quickly, as it does with animals such as snakes & spiders, it can take hours or even days before symptoms of poisoning become apparent. That's not to say that ticks aren't as deadly as other poisonous animals & it is advisable you take your dog to a veterinarian, just to be on the safe side.  

What is a Neurotoxin & What does Holocyclotoxin do?

A neurotoxin is a toxic substance which damages or destroys the cells of the central nervous system. * Holocyclotoxin is a neurotoxin which is  excreted from the tick's salivary glands into the dog. Holocyclotoxin inhibits release of acetylcholine in neurons. 

* Other examples of neurotoxins  are: 

Botulinum toxin from bacteria, this blocks acetylcholine release. 

Apamin from the honey bee, which blocks potassium channels. 

Versutoxin from the funnel web spider, which opens sodium channels. 

How do Paralysis Ticks get onto dogs? 

Stimuli such as heat & movement alert the tick to a potential host. They climb onto vegetation & when an animal passes, it waves it's forelegs (known as questing) until it makes contact with the host.

What are the signs of tick poisoning in dogs?

Symptoms of tick paralysis include;

• Loss of appetite

• Vomiting or dry retching,  excessive salivation, difficulty swallowing, difficulty breathing, coughing.

• Change to bark.

• Coughing.

• Noisy panting.

• Difficulty swallowing.

As symptoms progress you may notice;

• Limb weakness, starting in the hind legs, progressing to the front legs, appearing wobbly & uncoordinated, falling over, paralysis.

• Incontinence.

• Laboured breathing.

• Coma.

What to do if your dog has been poisoned by a tick?

Try to keep yourself & your dog as calm as possible. Remove food & water as poisoning can prevent the dog from swallowing properly, which in turn could lead to choking. Take it to the veterinarian as soon as possible. The longer you delay taking your dog to a vet, the worse the symptoms will become, which may lead to death. 

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 dog's skin as possible. Be extremely careful not to squeeze the body of the tick as this will inject more poison & pathogens into the dog's system. You can also kill the tick while it's still on the dog by using an appropriate insecticide, such as Frontline spray. 

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 you prevent tick poisoning?

Check your pet thoroughly every day for ticks. Start from the tip of the nose & work your way right down to the tail. Ensure you check between the toes, inside the ears (be careful).

Avoid allowing your dog to wander in the native bushland. However, ticks aren't found exclusively in native bushland. 

Regularly use insecticides such as the ones listed below if your dog goes outside. 

What treatment will be performed on a dog who has been poisoned by a tick?

Treatment depends on the severity of the symptoms, and is different from case to case. The greater the severity, the more care the animal will need & mortality rate increases, which is why it's so important to seek veterinary care as soon as you suspect tick poisoning. Symptoms may include pneumonia, high blood pressure, heart problems, vomiting & respiratory difficulties. 

If it is having difficulty breathing, it may be given oxygen. It may also be put on a drip to prevent dehydration.

Your pet will almost certainly be hospitalised & given antiserum. This serum (the clear part of the blood which contains antibodies) is obtained  from dogs that have been made hyperimmune via repeated exposure to paralysis ticks.

Recovery is dependent upon severity of symptoms. Generally veterinary treatment takes 2+ days. You will be required to care for your dog for some time after it has been discharged from the hospital also. 

Do paralysis ticks affect other animals?

Yes, ticks affect native animals too. Including marsupials, reptiles,  birds & dogs. The Bandicoot is a particular favourite. 

What is Lyme disease?

Lyme disease is the Borrelia burgdorferi bacteria which is transmitted via tick bites. More information on Lyme disease including symptoms & treatment can be found here.

Does Lyme disease affect dogs?

Yes, although it has yet to be proven that the Paralysis Tick passes on Lyme disease to dogs 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 dogch Lyme disease from your pet, but it is possible for humans to become infected from ticks. 

What is Queensland Tick Typhus (Rickettsia australis)?

Tick Typhus is a bacterial infection caused by the Paralysis Tick. 

Can Queensland Tick Typhus affect dogs?

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. 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 identifidogion. 

* References

* photos courtesy of Norbert Fischer; BVSc MACVSc

(Norbert's page seems to have moved, so I am now linking to Tick Alert, which Norbert appears to be a part of. This is an incredibly informative site.

Neurotoxin Info courtesy of Neuroscience for Kids

Neurotoxin Info courtesy of Washington State University at Vancouver