Highly contagious IBR on the rise in cow herds

Infectious bovine rhinotracheitis causes abortions and leads to massive losses in a naive cow herd

Sooner or later folks say, everything old is new again. In the case of infectious bovine rhinotracheitis (IBR), that is not what a cattle producer wants to hear.

“We are seeing IBR raising its head again in cow herds,” says Dr. Cec Ruschkowski of Oyen Veterinary Clinic.

The disease is often viewed as a feedlot problem associated with stressed calves. While it certainly causes illness in calves, secondary infections such as bacterial pneumonia can be treated with antibiotics. But when IBR shows up in a naive cow herd, it causes significant economic loss in the current year and possibly in years to come.

The IBR virus causes abortions in cow herds with no immunity, and losses up to 60 per cent have been reported, said Les Byers, manager of veterinary services for beef cattle and beef genomics with Zoetis. And a cow that has aborted an IBR-infected fetus will usually not rebreed in the same year.

“IBR caused by the bovine herpesvirus-1 can stay latent until stress reactivates it and the carrier begins to shed the virus,” said Byers. “The virus is highly contagious, spread primarily through nasal secretions.”

It was being controlled for many years by vaccination programs and closed herds, said Ruschkowski.

However, cattle are moving more often and producers are bringing in cow-calf pairs for summer grazing. As well, many producers buy replacement heifers where formerly they raised their own.

Complacency

And some producers have become complacent.

“Unfortunately some producers have backed off on their vaccinations,” said Ruschkowski. “Some thought it was a way to save a couple of bucks during BSE times. Some are questioning the need and effectiveness of vaccines.”

Ruschkowski said she’s had conversations with young producers who question the need to have their kids vaccinated against certain childhood diseases, and take the same view when it comes to herd health programs.

“These producers have no first-hand experience with the significant losses that can be caused from these diseases,” she said.

The vaccines available for IBR are quite effective, added Byers. There are also combination vaccines that protect cows against IBR, as well as diseases such as BVD, with just one vaccination. Modified live virus vaccines may cause abortions if administered to improperly primed pregnant cows so producers are advised to consult their vet on vaccine choice and timing. A properly vaccinated cow will pass, via colostrum, some protection to their calf that lasts six to eight weeks. After that, the calf needs to be vaccinated.

Ruschkowski promotes a herd health program as an important part of an overall biosecurity plan for a livestock operation.

Producers should find out what bugs are going around and get on a vaccination program, she said. They should also keep a separate set of boots and coveralls to use when helping out neighbours.

IBR is not a reportable or notifiable disease in Alberta and vets maintain client confidentiality. However, there is a veterinary practice surveillance network so they can gather information and discover when a disease such as IBR is increasing.

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