If It Ain’t Broke, Don’t Fix It

D. E. Larsen, DVM

A group of us younger veterinarians were seated around a table at lunch during the state Veterinary Medical Association meeting when Ed stopped by to visit. Ed was head of the large animal hospital at the new veterinary school that was just getting off the ground at Oregon State University.

After some small talk, Ed asked the group, “I am interested in how many of you guys use or recommend the Pasteurella vaccine in your practice.”

Everyone raised their hand except me.

“Did any of you guys read the article in the last Journal of the AVMA?”

“I read that article the other day,” I said. “I found it very interesting. When I was in school at Colorado State, Dr. Pierson told me to never use that vaccine because it was a terrible vaccine.”

“For those that didn’t read the article,” Ed said. “It is saying that current research shows the vaccine does more harm than good.”

“How is that possible? That vaccine has been used for years,” Scott asked?

“All the research says that the vaccine works by enhancing the white blood cell’s ability to engulf the bacteria,” Ed said. “That allows the bacteria to kill the white blood cell. And the debris from the dead white blood cells causes all the pathology in the dependent lobes of the lungs. They are planning to pull the vaccine.”

“Wow! That is hard to believe,” Scott said.

“Yes, this has been the widest used vaccine in cattle since the late 1940s, maybe the widest used vaccine in the world. For this profession to fail to recognize it as a problem is a major failure. I would be interested in what Dr. Pierson had to say about it, Larsen,” Ed said.

“Dr. Pierson just said it was a terrible vaccine. He did a lot of work in the feedlots in Northern Colorado. I spent a week with him, mostly doing necropsies in several rendering plants in Greeley. He said he would recommend I never use the vaccine. In fact, he recommended I decline to provide services to any herd who used the vaccine.”

“So he was just basing his opinion on his observations,” Ed asked?

“Yes, he was pretty astute. He was also a master with the stethoscope. He could almost draw a picture of the lung field of the steer.”

“Well, this is a good lesson for all of us,” Ed said. “This is why double-blind studies are so important. For almost the entire profession to think they were benefiting cattle by using this vaccine demonstrates that we make ourselves see what we want to see.”

“How are you planning to address the problem at the Veterinary School,” I asked?

“We are definitely going to have to rewrite our vaccination recommendations we hand out to clients. Educationally, it will be a good platform to discuss the placebo effect and how it even affects our ability to really see the results we are getting.”

“Yes, I think that I am losing faith in the way we repair the anterior cruciate tears in the dog,” I said. “I had the opportunity to look at a pair of knees on necropsy. One knee was repaired, and the other was not. On the gross exam, you could tell no difference between the two knees. Talking with the owner, he said that 6 months following the tear of the second ligament, you could not tell any difference in how the dog walked and ran.”

“There are a lot of people working on that problem,” Ed said. “But Larsen, I am interested in how your recommendations differ from everybody else since you don’t use Pasteurella vaccine.”

“I use the viral vaccines, and we practice a closed herd or at least a semi-closed herd approach in the herds that I manage. The only bacterial vaccines I recommend are the Hemophilus and Lepto vaccines.  I rarely see a case of pneumonia in my well-vaccinated herds. Unlike some of the backyard outfits that have pneumonia cases every year.”

“Maintaining a close herd is difficult for most producers,” Scott said.

“Sure, but any replacements are carefully selected, and they try to isolate them for a week or two before introducing them into the herd,” I said. “I don’t have any huge herds, and most of the guys do pretty well.”

“So why just do the viral vaccines,” Scott asked.

“Pasteurella is a normal inhabitant of the respiratory tract,” I said. “It is an opportunistic organism. When the respiratory system is compromised by a viral infection, it becomes susceptible to many bacterial invaders. Throw in stress and environmental factors, and you end up with shipping fever.”

“Well, we are all going to have to work from a different perspective for several years,” Ed said. “I understand that a couple of companies are already starting to work on a new vaccine. But with this experience, the FDA will be very cautious on their approval. I would expect it to take five or six years before we have a replacement.”

“What are you going to do then, Larsen,” Scott asked?

“Five or six years is a long time,” I said. “I guess it will depend on the data. But I firmly believe in the old saying, ‘If it ain’t broke, don’t fix it.’ If my herds continue to have no issues with the way they manage their vaccine programs, it will be hard for me to make a change.”

“I can see your point,” Scott said. “I also find it interesting that you had the chance to work with Dr. Pierson for a week doing necropsies. That kind of experience wasn’t available at Washington State.”

“We had a lot of large feedlots around Fort Collins and Greeley,” I said. “I worked in the Monfort’s feedlot in Greeley, on the weekends for a time. They had a hundred thousand head on feed at that lot and another lot the same size South of Greeley. That was also a great experience for me. But, of course, we don’t have anything close to that in Western Oregon.”

“Well, it has been an interesting discussion,” Ed said. “I’m glad I stopped by to chat.”

“So what is the status of the school,” Scott asked.

“We start our first class this fall,” Ed said. “They will graduate in 1983. It will be a little hard on them. They will take their first year and part of the second year here, then they move to Pullman to take the rest of their second year at WSU. They will take all the small animal medicine during their third year before returning here for their fourth year. Difficult, but at least they will end up with a degree.”

“Sounds difficult,” I said. “I was flat broke when I finished school in Colorado. I am not sure I could have handled all the moving expense, let alone the stress.”

Photo by Dylan Gillis on Unsplash