Tick paralysis increasing in cattle

Ticks are being found in increasing frequency in our food-producing animals and domestic pets.

They cause concerns because some species carry transmissible diseases that can affect humans, such as Lyme disease. Others cause blood-loss irritation and others cause paralysis. The most commonly found tick on cattle in Western Canada is the Rocky Mountain wood tick (Dermacentor anderson), commonly referred to as the wood tick.

This external parasite releases a neurotoxin through its mouthparts that can paralyze livestock.

In certain areas of the country it can be a major health problem in cattle.

Producers must try and identify the specific pasture or bush location the ticks come from so they might avoid having cattle in those areas over the winter and spring.

To time treatment for ticks, producers must focus on when they start to see a few of them and check to see if the problem, especially with tick paralysis, has been a problem in the past.

Ranchers in British Columbia who deal with this problem say ticks are moving north and because there are limited products available, control and treatment have become more difficult. As well, cattle may be inaccessible.

I have heard of instances of tick paralysis affecting bison and horses as well. Be careful when processing or treating affected livestock and do a tick scan of yourself when in these endemic areas.

People fear ticks and for good reason. We need to identify the species of tick and frequency of occurrence and then proceed with treatment. There are tick experts available at the federal agriculture research centre in Lethbridge that are researching tick distribution and new methods for treatment.

Downer cattle affected with tick paralysis must be treated quickly. You may notice cattle appear to stagger because it generally causes an ascending flaccid paralysis. It takes a couple days after getting the ticks for clinical signs to develop.

One must watch closely at or around the time downers have happened in the past. The key is finding them quickly and treating and removing the ticks.

Some may be almost able to rise and others go right down into a lateral or flat-out position. The further the tick paralysis has progressed, the poorer the recovery.

Any ticks found need to be removed as soon as possible. It’s often beneficial to clip the area around the tick to help with removal and future grooming. The hair coats are generally very long in the spring and is not conducive to the animals licking them off. Downer animals may have more ticks crawl onto them. Treatment then involves one of a few tick pour-on treatments available in the marketplace. See what your local veterinarian recommends and treat with the correct pour-on dose as soon as possible.

Prevention would involve not placing cattle in areas that are known tick reservoirs until later spring. Also, producers can preempt the tick paralysis and apply tick treatment. Another good preventive measure is to use cattle oilers with products that have tick control on the label.

As it warms up, ticks fall off and complete their life cycle and a potential crisis is eliminated, until the following year.

There is no real long-term residual treatment.

Don’t forget to give good quality feed and water when animals are down for 24 hours. Electrolytes may have to be given in the water and if the animal is struggling to rise, NSAIDs and selenium may be necessary.

We will all have to improve our monitoring and diagnosis of external parasites, including lice, in the future.

Roy Lewis works as a technical services veterinarian part time with Merck Animal Health in Alberta.

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