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Pathogen Surveillance In Cattle Is Profitable

Pathogen Surveillance In Cattle Is Profitable
Continuous, pathogen monitoring and diagnostic testing yields precision vaccination and treatment protocols that save feedyards money.

Imagine less than 1% mortality and about 10% morbidity for loads of put-together lightweight calves (325 lbs.) from the Southeast freighted to starter yards in Kansas. Imagine cutting average death loss and morbidity by 40-50% and significantly reducing the prevalence of major pathogens (Table 1).

That’s what Cattle Health Management Network (CHMN) based in Meade, KS, is accomplishing for clients by working closely with Vet Bio Inc. (VBI), San Angelo, TX. CHMN client yards represent about 1.5 million head of cattle, and they’re improving the health picture with a comprehensive, integrated pathogen surveillance protocol that hinges upon aggressive diagnostic testing and reporting.

If you’re a feedyard manager or feedlot veterinarian who has no use for diagnostic testing for live animals, keep your pony hobbled. Scott Crain, Nate McDonald and Gary Bryan, long-time CHMN veterinarians, were in that same camp for most of their careers. By the time they’d get diagnostic test results back – typically in 10-14 days – the animal in question was cured or dead. Besides, they could send samples from the same animal to three different labs and get different results from each one.

Specifics vs. generalities

What began to change their minds was too many long-day cattle ending up in the dead pile. The cattle showed clinical symptoms of bovine viral diarrhea virus (BVDV) and testing showed the cattle were chock full of the virus; even though the cattle were vaccinated for BVDV multiple times. By working with VBI, they figured out BVDV Subtype 1b was the culprit, but no commercial BVDV vaccines were available that contain BVDV Subtype 1b.

Ultimately, CHMN formed a coalition of likeminded veterinarians – Professional Veterinary Associates (PVA) – to collect and submit BVDV samples to a national databank. Through a process called antigenic cartography (see “Gunning for a New Old BVDV Strain” in September 2009 BEEF), PVA monitors the differences of specific BVDV strains showing up in member yards and then develops autogenous vaccines to battle specific bugs.

Experience with that approach got Crain and McDonald wondering about other proactive possibilities. They wondered what might be possible if they knew the specific bugs they were dealing with everytime, and which vaccines and antibiotics were most effective.

To do so, they knew they had to find a way around the long lag times for lab results. They also knew they’d have to collect and submit thousands of samples. That meant test reporting had to be fast and in a format that allowed easy sorting and managing of the resulting data.

Old tools, new uses

“It always comes back to pounds and dollars and cents. At the end of the day, this is improving cattle health to the point that it’s having an economic impact,” says Jim Bob Harris, VBI owner and manager. “A lot of this isn’t new science – diagnostics for pathogen identification and sensitivity – but most people aren’t aggressive enough in using it.”

“Most everyone looks for the same bugs, but we do so differently,” says Dale Weise, VBI assistant manager.

VBI developed a proprietary method that combines conventional virus isolation/propagation with polymerase chain reaction (PCR) testing, which is more sensitive than either one is alone.
Likewise, everyone can test cattle dead or alive.

“We’ve always posted everything. Before this surveillance system, though, our diagnosis was based on visual evaluation,” which has its limitations, Crain says. He shares a prime example from last fall.

A load of cattle showed up at a client’s yard and literally began dying coming off the truck. It looked like a textbook example of cardiac histophilus based on the necropsy, so that’s what Crain began treating.

When the test results came back, though, BVDV was the real culprit. He saved cattle that he couldn’t have without the surveillance infrastructure in place.

Don't post, don't know

“If you don’t post them, you don’t know. What appears to be a death due to bloat may be something else,” Crain says. And, if you don’t verify a visual diagnosis with testing, he says it’s easy to be misled.

False positives are worse than false negatives because they can lead you to ignore what could be a ticking time bomb, he adds. The foregoing example illustrates that point.

Today, CHMN’s protocol involves testing cattle as they enter the hospital pen, a portion of selected loads of cattle on arrival and, in some cases, a portion of cattle before shipment to a client yard.

“This gives you the data to make evidence-based decisions; then, your experience tells you whether you’re right,” McDonald says. “Culture and sensitivity data enables us to create more precise vaccination and treatment programs.”

Those flyweight cattle mentioned at the outset? The success stems from a combination of factors. McDonald explains the pathogen surveillance system allows them to do such things as time metaphylaxis differently. It allows them to choose specific vaccines and timing based on the DNA of the bugs the calf is carrying. Trends show them how specific bugs attack relative to the number of days on feed.

“For example, in some cases, a single antibiotic won’t kill two different bugs that are present. By knowing that, we can use a combination of products for treatment,” McDonald says. “We couldn’t do that if the data wasn’t reported to us in a way that we could sort and use.”

At the same time, McDonald emphasizes their success with those flyweight calves also has to do with specific management – like ensuring that calves have a minimum bunk space of 18 in. and minimum pen space of 250 sq. ft.

Bryan adds: “Our practice has adopted this as standard operating protocol. Before this, we had no way to gauge the effectiveness of our vaccination and treatment programs except through death loss and close-outs.”

Developing a surveillance system

CHMN veterinarians believe these are the primary keys to an effective pathogen surveillance system.

• A trained feedyard staff to post deads and collect samples. “You can’t find things by sampling one or two animals every now and then. You’ve got to collect and send lots of samples; you have to do surveillance all the time,” McDonald explains.

• A commitment from the feed-yard manager and staff to post all deads all the time. “To do this, you need the cooperation of your consulting veterinarian,” Harris says. “He has to be willing to train the people responsible for posting deads and collecting samples. He has to be willing to use the data.”

McDonald adds that posting and sample collection take only a little more time. Plus, Crain explains, the system results in less labor for pen riders and more economic return for cattle owners because there are fewer cattle to pull and treat.

• Handle samples properly and ship overnight. “Bad data is worse than no data,” Crain says. “It is too easy to test too few cattle too infrequently and feel like that is surveillance and make the same mistakes we used to make in collecting and preparing the samples. ”

• Work with a diagnostic lab willing to ensure that samples are processed within 30 hours of collection. How quickly samples are processed at the lab, testing procedures and other factors, have a dramatic impact on surveillance performance, McDonald says.

Viruses, for example, can degrade rapidly. Both time and heat enhance degradation. So, getting samples from dead animals before too much time passes is key. Once the sample is collected, it should be kept cool and sent overnight to the lab.

That’s where communication with a cooperative lab comes into play. Getting the sample there overnight makes little difference if the lab lets it sit for another day or so before processing it.

“Our experience shows that if more than 30 hours passes between the time the sample is taken and when it’s prepared in the lab, your ability to isolate the organism is much more limited,” Weise explains. “By that time, we need to have the virus or bacteria back in a healthy growing environment.”

• Real-time data reporting in a format that’s easy to sort and manage. “Within four days, they’ll know what they’re dealing with. We’ll usually have bacteria identified in 24 hours and mycoplasma in 48. Viruses will take 5-10 days,” Harris says.

But, they won’t wait until all the test results for a sample are available. Instead, each result for a sample is posted online as soon as it is known.

“The vet needs to have a relationship with a skilled, well-equipped diagnostic lab that’s willing to do things like receiving and processing samples within 30 hours of the time they’re collected; and a secure website for prompt reporting,” Harris says.

“Most people aren’t doing surveillance to the point where they can go back to the data and say, ‘I know it looks like this specific bug in the past, so I know that using this combination of vaccination and treatment should yield this specific range of results,’” McDonald explains.

“Our yards expect this level of care. We spend less on prevention and treatment because surveillance allows us to be more precise,” Crain says.

This isn’t doctor-by-numbers medicine. There are no cookie-cutter recipes. The point is pathogen surveillance enables CHMN to limit the number of failures in an economically meaningful way.

“If you’re not conducting surveillance, you have no idea what battle you’re trying to fight,” Harris says. “If you don’t continue to do it, you don’t know if you’re winning the battle. And, if you’re not thinking outside the box as you conduct the diagnostics, you’ll miss emerging diseases.”

Sidebar: Questions that surveillance can answer for cattle owners.

As you start cattle or prepare to send cattle to be fed, ask your feedyard to share its pathogen surveillance program results with you and your veterinarian.

  • What bugs are being seen today?
  • How much of each bug is present?
  • What to vaccinate against?
  • What specific vaccines to use?
  • If an animal dies, what did it die of specifically?
  • Was there a virus or underlying cause that should be included in the vaccination program?
  • Is it a pen problem or a yard problem?
  • Should the starter program be adjusted?

Sidebar: Questions that surveillance can answer for feedlot managers.

  • Why particular vaccines and antibiotics are being used?
  • What are they dying from and what evidence tells me that?
  • What’s causing it?
  • How can it be prevented?
  • If it’s in progress, how can a wreck be avoided?
  • Can surveillance help market the yard to current and prospective