Resurgent Mycoplasma hyorhinis causes debilitating arthritis in late finishing

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Infectious arthritis caused by Mycoplasma hyorhinis is gaining ground in hog units where it infects neonatal pigs and develops into severe lameness in market hogs, according Douglas Powers, DVM, veterinarian with Four Star Veterinary Service, Rushville, Indiana.

“Today Mycoplasma hyorhinis is starting to cause a lot more problems,” he said. “We’re seeing issues in the nursery and subsequent issues in the finishing barn with severe lameness, and some even dead on arrival at packing plants.”

Sow transfers to pigs

M. hyorhinis typically enters a sow herd through gilt replacements. It then circulates among the sows and is passed on to piglets in the farrowing house.

“The peak level of infection in pigs is starting around 3 to 5 weeks,” Powers said. “Then it starts to go systemic through the body and causes other issues.

“Early on, you can have some lethargy, fever and pigs not doing well in the nursery. If you follow those pigs downstream, we can start to see some ear-tip necrosis, side sores. Then we start to see the severe lameness in the hind legs and the hocks.”

Damage from severe arthritis

When health issues occur in the nursery, Haemophilus parasuis is the usual suspect. But Powers says an investigation often finds M. hyorhinis is the culprit.

“Some people think it’s a secondary disease, but I think it’s probably primary,” he added. “It can cause quite a bit of health issues on its own, especially in the high-health herds.”

If the infection hits hard in the nursery, it leads to heavy mortality or opens the door for secondary infections, he adds.

“We have theses absolutely perfect, healthy pigs…then all of a sudden they’re lame,” Powers explained. “They’re dog-sitting; they can’t get up; they don’t go to the feed and water as much as they need to; and then they start to get that severe arthritis from the damage.”

The decline continues for the arthritic hogs until market when some of them cannot make it on the truck and become downers.

Death losses due to M. hyorhinis damage can be 4% to 5% during the last 4 weeks in some finisher barns, Powers said.

Testing and treatment

If Powers sees issues in the nursery, he uses a polymerase chain reaction test to check for M. hyorhinis. If the virus is present, he uses an ELISA (enzyme-linked immunosorbent assay) test to see if it is causing clinical disease.

“We will look at those ELISA levels to see what level of infection is in the herd and [if] we need to implement either an antibiotic regimen to control it or a vaccination program,” he explained.

In the future, he sees where elimination of M. hyorhinis in some operations will be warranted.

“Now that we have the ELISA, we can look to see how broad spread it is and see if we can put some programs in to try to eradicate it,” Powers said. “I think eventually that needs to be our goal.”



Batch farrowing benefits Indiana hog operation

Batch farrowing made sense for Nate and Doug Hoeing’s sow operation. The brothers run a 1,200-sow operation on a family farm in Rush County, Indiana. Farrowing sows once a month instead of weekly offers a couple of major benefits.

“The batch system is labor saving,” Nate said. “We can do the work ourselves and only need hired help at weaning to move sows and load pigs. The rest of it we can handle.”

“Plus, now we have a larger group of pigs at weaning and they are easier to sell,” he added. The Hoeings wean about 2,000 pigs at a time, which are more easily placed in large finishing barns.

Growing in use

Batch-farrowing systems are on the increase, according to Doug Powers, DVM, Four Star Veterinary Service. He works with the Hoeings and other clients who are using the system.

“About a third to half of our clients are going to a batch system,” he explained. “They get a bigger group of pigs to fill a 2,500-head wean-to-finish barn as quickly as possible. At the same time, they don’t leave any small pigs behind to transfer disease to the next group.”

Batch farrowing isn’t for all operations, though. The size limit for the system is about 2,500 sows, Powers said. After that, it’s difficult to make it work.

How it works

On the Hoeing farm, the brothers are busy 2 weeks of the month when they begin weaning. Starting on a Monday, they move sows and weaned pigs out of the farrowing crates and completely wash the barn. By Thursday, sows ready to farrow are moved into the clean facility. Usually 190 to 200 sows farrow in each batch.

On the weekend, breeding starts for sows moved out of the farrowing barn. A typical breeding group is 210 to 220 sows. The brothers also get ready to start processing litters, which takes place that next week. Any sows not farrowing by Thursday of this week are induced.

“Then things slow down for a couple of weeks so we can get other things done,” Nate said. The pigs are weaned at 17 to 24 days of age.

Strong litters, sows

The Hoeings use three farrowing barns and fill all of them up at the same time. Their gestation facilities include rooms with 600 individual crates and an updated pen-gestation system that holds 400 sows.

They moved to self feeders in farrowing to help sows improve their condition and to increase weaning weights.

“On the day the sows farrow, we feed them very little,” Nate explained. “On day 2, we give them 5 pounds and then they go on a full feed (ad libitum).”

This feeding regimen improved the herd’s overall sow condition. The last group of sows averaged 14.5 pounds per weaned pig weight and weaned between 11 to 11.25 pigs per litter.

One disadvantage to a batch system is if a sow doesn’t breed, it won’t necessarily cycle back in a regular breeding week. To help them cycle within a group, an altrenogest supplement is fed to the sows. Unbred sows are culled.

High health

The farm has a high-health status. It was depopulated in 2018 and repopulated with high-health gilts. Today, it is negative for porcine reproductive and respiratory syndrome and mycoplasma. The herd has very few scours or respiratory issues.

The Hoeings powerwash and disinfect the facilities between batches and have extra time to allow the rooms to dry. And because all pigs are moved out of the facilities, none remain to transfer disease. All of this adds up to good herd health.

For the brothers, good herd health and the batch system frees up time for them to do their other chores, like manage a herd of 100 brood cows, and help their father with his crops.