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How to tackle mortality-causing lameness in finishing hogs

24 September 2021, at 11:57am

Lameness is now the leading cause of mortality in mid- to late-finishing pigs. How did lameness develop into such a big problem?

Mike Eisenmenger, DVM, Swine Vet Center, and Kathleen Wood, DVM, Christensen Farms, addressed the lameness issue during a recent webinar produced by the Swine Health Information Center. Both shared insights from their experiences managing lameness in finishing hogs.

First, pathogens that used to drag down finishing pigs are under control. “We worked really hard to remove the major pathogens that flow out vertically from sow farms,” Eisenmenger reported. “We want to be able to give the nursery-grow-finish system PRRS- (porcine reproductive and respiratory syndrome) and Mycoplasma hyopneumoniae-negative pigs so we can get the lowest mortality possible.

“In reality, even though mortality has improved, it seems we hit a baseline threshold. It is getting harder and harder to make continuous improvements…and there are a multitude of reasons.”

Lameness caused by bacterial arthritis has become the big reason for mortality today. Eisenmenger credits the infectious “small bugs”— Strep suis, Mycoplasma hyorhinis and hyosynoviae, Actinobacillus suis, Glaeserella parasuis — for the arthritis.

25% to 40% lameness new normal

Industrywide, lameness affects 10% to 25% of hogs in grow-finish. But Wood was stunned to see how much lameness increased during the COVID-19 shutdown.

“It has been on the upward trend in the summer months,” Wood said. “Recently 25% to 40% severe stiffness or lameness is not uncommon. Lameness is the No. 1 cause of mortality in our mid- to late-finish hogs. Unfortunately, it has become the new normal.

“Mild lameness has always been there,” she continued. “We just weren’t recognizing it as an issue because it doesn’t raise red flags as a cause of high mortality. Stiffness and subtle lameness aren’t alarming, and they don’t trigger the need for immediate treatment in the industry. But we need to change that. We need to start reacting to low-level mortalities.”

Back to basics: necropsy it

A focused, coordinated effort to reduce lameness by Christensen Farms started with the veterinary team going into the field and regularly working with service staff on necropsies to help identify causes for stiffness and lameness.

“Our service team is very well trained, but there are still nuances and additional things that they can learn about on causes of lameness and post-mortem exams,” Wood explained. “We started cutting open a lot of pigs with them and getting our team to open pigs on their own. They weren’t confident cutting open joints, so we walked it through with them.

“It’s not always about just the heart, lungs or brain,” she added. “If a pig can’t walk properly, it’s chances of making it to market as primary pig has severely decreased. This means that getting into the bones and seeing what’s going on is an obvious but underlooked necessity.”

The results of the additional training are a game changer for Christensen Farms, she added. It reset what the farm’s service teams expect with lameness.

“Pigs are not supposed to be stiff,” Wood said. “Lameness and stiffness are not normal. Pigs are not supposed to be in pain when walking.”

Treat early signs

The second part of the Christensen Farms plan involves early recognition of lameness, with a priority placed on treatment.

“We have to do what’s right for the pigs,” Wood said. “Treat them. We are limited in our options, especially with anti-inflammatories. But they are equally as important as antibiotics and give pigs pain relief. In our system, we are limited to two, and there are withdrawal times that make it difficult to use them in late-finishing pigs.”

To help caregivers identify when to treat, Wood created a chart with photos of pigs showing three stages of lameness, with the required treatments. The chart helps farms quickly identify when help is needed.

Work with diagnostics

Another part of the lameness fight means working closely with the diagnostic lab. Wood wants all lameness samples sent to the lab with a detailed history and other communications of the problem to help the lab more quickly find the cause.

Also, samples sent to the lab should be the entire limb and not be fluid from an open joint. Conditions in the barns are not sterile enough to collect the fluid, according to Wood.

Other interventions

Wood also works with other departments at Christensen Farms to determine the best treatment options. For example, she suggests working with the marketing group if 5 days are needed to provide medication with a withdrawal time to get on top of a lameness issue.

Another department that can help with lameness issues is nutrition. “Nutritionists are your friends, not enemies,” Wood said. “Ask them what we can do to make this better and be open to their suggestions. Spending time with them in the field is a great way to get aligned on the issue.

“And don’t forget the sow farm,” she added. “What are they selecting for on confirmation? What can we do to knock down their bug load? How about maternal immunity? Everything goes downstream.”

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