John Lauder knows all about the devastation that tiny ticks can cause.
“Its legs are moving, like it’s trying to ride a bicycle,” the British
Columbia rancher says, describing finding a steer on its back.
“You know it’s got into a mass of ticks.”
Lauder, who raises cattle in B.C.’s Nicola Valley, treats 450 of his
yearling calves twice each spring for ticks – once before turning them
out to pasture at the end of March and again at the first of May.
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He has more to worry about than most prairie cattle producers.
While Rocky Mountain wood ticks are an irritant to most western
Canadian cattle and sheep producers, they can be fatal on the livestock
ranges of the Nicola Valley.
The rolling glacial till plateaus of bunchgrass grasslands, small
marshy lakes, and Douglas fir and Ponderosa pine forests trimmed with
aspen parkland make prime cattle pasture.
But there is something sinister in these scenic, wooded and sometimes
steep grasslands. The area is also home to a special type of wood tick
whose adult females can drop a full-grown cow on its back in a matter
of a few days or even hours.
Tim Lysyk, a research scientist with Agriculture Canada’s Lethbridge
Research Centre, is trying to figure out why.
“These are special,” he said. “Recently we have discovered they have
(genetic differences) from the Rocky Mountain wood ticks found in
Alberta and Saskatchewan.”
Paralysis-causing ticks can also affect horses and humans and are also
found in Montana, Idaho and Wyoming.
Lauder has seen these ticks in
action.
“It’s not like a true paralysis like you might think of it. But it can
bring an animal down pretty quick if it wanders into a big mass (of
ticks). They get all wobbly, then a bit stressed and down they go.”
Cattle can be saved if they are found after only a few days of tick
feeding and are treated quickly, but animals that are not rescued
“pound their heads on the ground, get pressure sores. They can fall
down a slope. Predators get them. It’s serious business.”
“Tick spit” eventually paralyzes the animal’s chest muscles and death
follows due to asphyxiation, if it hasn’t already been killed some
other way.
Lysyk suspects paralysis is caused by a protein injected into the
animal while the tick feeds.
Lauder has had to deal with the problem all of his ranching life.
“If we find them alive I take out the generator and electric clippers.
We clip the ticks off and then re-hydrate the animal by pumping warm
water into it. They can be up and grazing again in minutes once the
ticks are off.”
The sequence of infection generally takes between two and five days.
Between 75-150 engorged ticks will paralyze a yearling beef animal, and
20-50 for a ewe, which works out to about 14-17 ticks per 45 kilograms
of body weight.
Younger animals are usually most susceptible because of lower body
weights and poorer self-grooming skills.
Lauder said prevention is the key.
“It costs us a dollar for the medicine and a dollar to put the cattle
through the chutes each time we treat them. But if you don’t, this is
the kind of thing that could wipe a person out. You could lose a lot of
cattle if you didn’t treat and got a mess of ticks.”
Lauder said the ticks are unpredictable.
“We haven’t seen any on our place this year. The neighbour down the
road a mile, he’s got them this year.”
Lysyk said the ticks’ unpredictability makes control impractical, but
Lauder sees it as part of raising cattle in B.C.’s Interior.
“We all treat, though. It’s a part of raising cattle out here.”
Lauder treats his cattle with the permethrin insecticide Ectiban 25 EC.
The federal government has approved Ectiban for use in beef cattle
through a minor use registration. Lauder said it was requested by the
B.C. Cattlemen’s Association as a “stop gap measure until we found
something better.”
Until a couple of years ago, he and his neighbours used Lindane, an
organo-chlorinated pesticide in the same chemical family as DDT. It
will be banned from use in Canadian agriculture in 2004 because of its
long-term effectiveness and durability in the environment.
It is this staying power that made Lindane the only method of control
from the time it was introduced in 1943 until recently.
Newer products that can be sprayed or poured onto cattle don’t last as
long as Lindane, but a three-year study funded by the federal and
provincial governments and local and national producer groups
identified a replacement.
According to the B.C. Cattlemen’s Association, the study found that
while Saber Pour-On, manufactured by Schering-Plough, isn’t as
effective as Lindane, it did provide five weeks of protection.
While not enough to carry an animal through the two-month tick season,
its coverage time was two weeks longer than other products that were
tested.
Lysyk and a team from the B.C. agriculture department, the federal
Kamloops Range Research Unit, and the United States Department
Agriculture research service in Laramie, Wyoming, are working to
develop a vaccine to fight the parasite.
“We know that some animals develop immunity to the ticks. Now we are
working to find out why and create a vaccine that will protect without
the use of sprays or other chemicals,” Lysyk said.
“It’s difficult work though, collecting and testing tick spit.
Luckily, in Canada we have some the world’s few experts in the area of
tick spit and they have taught us a few things about it…. I expect we
will develop a vaccine that provides immunity. But there’ll be more
tick spit to test first.”
