I received a call from a dairy farmer last July with cows and heifers coughing at grass. This had been going on for several weeks and his milk yield was now 30% below target. Milk solids had also taken a hammering. Several of his cows were noticeably thin.
I called out to him and examined the sick cows. Many were in poor body condition and most were coughing and had clear nasal discharges. A lot of them had high temperatures. I decided to question the farmer to get a history of the problem.
He told me he first noticed the replacement heifers coughing about one month earlier. He got talking to one of his farming neighbours who advised him to vaccinate with a live IBR vaccine as he had heard of other farmers who had been advised to do this by their vets.
He mentioned that he had given this vaccine subcutaneously. This did not stop the problem however and gradually more animals became ill. I asked if he had given any worm doses recently. He said he had dosed the heifers back in May but the cows don’t routinely get a dose. I asked what product he had used on the heifers but he couldn’t recall and said it was an old dose he had used before and thought they would all do the same job.
I decided I would have to take some samples from the sick animals to try and figure out what was causing these issues and to give a clear treatment plan going forward. I took blood samples, nasal swabs, dung samples and a bulk milk sample. When the results came back from the lab the main findings were high RSV levels in the blood and lungworm larvae in the dung samples. RSV (Respiratory Syncytial Virus) is a respiratory virus which was thought to only cause problems in calves but is increasingly seen as a cause of respiratory disease in adult cows.
Based on these findings, I advised the farmer to do his cows with eprinomectin pour-on and dose his heifers with levamisole. I also advised vaccination with an intranasal vaccine for RSV. I had advised him to switch to once a day milking to allow his cows to recover.
One month later there was a huge improvement on the farm. The cows were back milking normally, there was no coughing to be heard and no more runny noses.
The long-term plan is to continue to vaccinate against RSV and to develop a detailed worming plan. It is vital to have a plan for vaccination and worming on modern farms. If this farmer had been doing this he would have avoided this outbreak and all the lost revenue due to decreased milk yield and treatment costs.
I suppose there are several important lessons to learn from this experience. Firstly, the power of good communication skills. I only learned by chance that the IBR vaccine had been given under the skin. This should have been given intramuscularly, so would have had no effect and was wasted money. Also it was obvious that the farmer hadn’t a great understanding of the various worming products on the market and I can’t blame him. Worming protocols should be simple to implement but the vast array of products on the market would confuse anyone.
Secondly, I learned the foolishness of making assumptions. We make assumptions to try to save time but in reality it can end up costing us time and money. The farmer (thanks to his well-intentioned neighbour) had assumed IBR was the cause of his coughing cows. There has been much talk about IBR and much marketing of the vaccines against it. Whilst it is a very serious disease if an outbreak does occur, I believe that a lot of respiratory disease is blamed on IBR when there are a multitude of other possible causes.
I would have assumed that hoose would have been very likely given the time of year. However, if I just relied on this educated guess I could have failed to diagnose the RSV issue. The value of proper and thorough diagnostics cannot be overstated in a pneumonia outbreak.