Beware of paralysis ticks (Ixodes holocyclus)

Published in The Nimbin Good Times – October 2016


The tick season is well and truly upon us and I’ve been finding them attached on several horses recently.  Given that ticks can cause some horrifying reactions in some equines, it’s advisable to be armed with valuable information that may help with any important decisions concerning their welfare. Those decisions may save a life!

The saliva of a paralysis tick contains a particularly nasty toxin which is both neurotoxic and cardiotoxic, meaning that it affects the nervous system and heart muscle and can paralyse and kill a horse. They can be found around bushy vegetation and paddocks that are used as wildlife corridors in areas where there’s shelter from direct sunlight. When they need to feed they climb the taller plants and structures and drop down onto passing animals.

They stay attached whilst engorging blood from their hosts from 1 – 7 days during which the toxin spreads with clinical signs appearing around the third day, and toxicity peaking around the fifth day.

The symptoms of tick toxicity include lethargy, falling or lying down, off feed, peripheral nerve dysfunction, lameness, wobbliness in the hind legs or all the legs, reduced muscle tone, difficulty eating, impaired respiratory function, heart and muscle dysfunction, debility and sweating. If any of these symptoms are present you need to act immediately. If you find ticks, remove them and keep the horse in a cool stable away from direct sunlight since the toxins are more readily spread around the body during movement and hot weather.

Veterinary intervention uses anti-tick venom which is very effective if caught in time but as I’ve found, it isn’t always easy to get one when needed. In this case I was able to make a tincture to address the symptoms and was lucky to have caught it early enough to save our pony. Unfortunately, other complications can develop without early intervention, so it’s important to act quickly! A study on paralysis ticks in horses presented at an AVA conference stated that there was an alarmingly high mortality rate of 26% out of 103 horses analysed in the study, and 35% of the surviving horses went on to develop further problems.

It’s important to do a daily search for ticks which are found mostly on the upper body, around the head including the lips, chin, around the eyes and ears, back of the head, neck, in between and around the front and back legs. Just feel around for a lump and if it’s a tick, remove it carefully so that the head is extracted along with the body. Some people turn the tick around 180 degrees to ensure the entire tick is removed. There are several methods but I’ve read that veterinary advice is not to use topical sprays because they tend to promote further production of toxins when the tick is dying!

Prevention strategies include:

  • Keeping horses away from bushy areas and overgrown hedges
  • Ensuring the pasture is kept low
  • Regular use of pyrethrum based insect sprays
  • Daily checks for ticks
  • Herbal dietary supplements to aid the body’s defence

Not all horses will go on to develop these symptoms as many develop an immunity having lived in tick infested areas for some time and those with less body density are probably more at risk. Ponies and foals and are in the risk category but even a large horse can be affected by the paralysis tick, especially taking into consideration the movement of animals from tick free areas and animals with a compromised immune system.

Given that these symptoms are similar to those of the Hendra virus, it’s advisable to be alert and act quickly to avoid a catastrophe.

Les Rees Equine Naturopath


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