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Western cattle seeing more exposure to foothill abortions

Progressive Cattleman Editor Cassidy Woolsey Published on 23 March 2018

A 10 percent calf crop – just the thought can make even the toughest rancher cringe. Although it sounds like a nightmare or a poorly managed cow herd, it’s actually what some Western ranchers are battling due to a tick-transmitted disease commonly referred to as “foothill abortion” or epizootic bovine abortion.

During the NCBA Cattlemen’s College earlier this year, Dr. J.J. Goicoechea, rancher and Nevada state veterinarian, cautioned attendees about the pajaroello tick. He said, “I don’t know about you guys, but I can’t live with a 10 percent calf crop. It’s a growing problem in the West, and everyone needs to be aware of it.”

No stranger to ranchers in California, Oregon and Nevada, the pajaroello tick resides in the soil and organic matter in deer and cattle bedding areas. Unlike its hard-bodied cousins that attach to their host for seven to 10 days, the soft-bodied pajaroello tick is only on the animal for 20 minutes, Goicoechea said, explaining why they have been slow to spread into other states.

“They are creeping up into Idaho, and we’ll have it up there pretty quick,” he warned attendees. “We [recently] diagnosed two additional herds in east-central Nevada. So the disease is on the move, we are just finding more and more ticks.”

The window of susceptibility to this disease is minus 30 days to 150 days. This means: If the heifer or cow is bitten by the tick and exposed to the bacteria 30 days before the bulls are in, plan on her aborting.

Infected pregnant cows or heifers show no obvious symptoms, and the infected fetus doesn’t show signs until about 100 days post-infection. Cows can carry the infected fetus to term, but the calves are either stillborn or weak.

Some signs of foothill abortion are:

  • Enlarged lymph nodes, especially the prescapular nodes, which are in front of the shoulder blade at the base of the neck on the side

  • A straw-colored fluid in the abdomen

  • Thick, red hemorrhages around the eyes, under the tongue or roof of the mouth

  • Enlarged liver with a rough discolored surface

“These fetuses look fresh,” Goicoechea said. “Everyone who has lost a fetus knows they don’t look very fresh and you’re going to have a hard time finding anything. They slip hair, and they don’t smell good. That’s not the case with foothill abortions.”

There is an effective, live bacteria-based vaccine available with about a three-year immunity, Goicoechea said. This vaccine can be administered at the same time heifers are brucellosis (bangs) vaccinated. However, it should not be administered 60 days before breeding or less than six months in gestation to avoid losing the fetus from the vaccine.

“The key here is really avoidance of exposure,” Goicoechea said. “If you’re going to graze infected pastures, you can’t do it with heifers under six months pregnant or cows if they have never been there; you’ll want to use stockers first. Or you’ll need to change your breeding days if that’s at all feasible.”

Last, Goicoechea said if foothill abortions are to blame, it is OK to keep open cows and heifers. But be sure it’s not a trich problem or anything else.

“What we find is: A lot of ranchers are going and buying another set of heifers or cows that weren’t raised in that country. So what happens next year? She comes up open,” he said. “If you are in an area with this, you are going to have to expose those or vaccinate.

What a lot of guys have been doing is breeding as 2-year-olds and calving as 3-year-olds. Yes, it’s expensive, but it’s no more expensive than losing half of your herd.”  end mark

Cassidy Woolsey
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