Winter has returned to near normal weather patterns compared to last year’s milder season in the Midwest. Cold, windy conditions have brought with it a cold weather foe to pork producers: Transmissible gastroenteritis (TGE).
TGE is a virus that infects pigs of all ages and causes diarrhea with vomiting. The disease is more severe in young piglets, often leading to death due to dehydration and profuse diarrhea.
In weaning-age pigs or older, the disease is less pronounced due to the animals’ ability to withstand the diarrhea.
A more chronic or endemic form of TGE can occur in herds where herd immunity is incomplete. Endemic TGE can be seen year ’round, compared to the more common, acute outbreaks generally seen in cold weather.
The virus is extremely contagious. Ingestion of just a few virus particles can cause infection in the pig. Often, clinical signs are observed within 1-3 days after exposure.
TGE virus is hardy during cold weather, allowing many inanimate objects (boots, trailers, equipment) and some birds, through fecal contamination, to carry the virus. Biosecurity measures are important for preventing exposure.
Case Study No. 1
This client is a weaner pig buyer who contracts with a 2,000-head sow unit to purchase weaned pigs weekly. The client’s farm has two nurseries and several finishing barns to house the pig flow from the sow unit. Twice a week, the sow unit delivers pigs to the nurseries. Each week, the client hauls pigs from the nursery to the finisher barns and the packing plant.
This past December, after a recent winter storm, my client called to describe a sudden onset of diarrhea that was affecting finisher pigs. He had placed them on water medication, but the pigs were not responding.
I visited the two finisher barns and found the oldest pigs had been in the finisher for three and four weeks. Diarrhea had started near the entrance door and was quickly making its way, pen by pen, to the other end of the barn. The diarrhea was watery and pig activity level was suppressed. I necropsied two pigs that had died during the day and submitted tissues to the lab.
The next finisher barn had received pigs only one to two weeks ago. Diarrhea started 24 hours after the last delivery of pigs. These pigs were also depressed, with widespread watery diarrhea and some vomiting. I collected more samples for submission from this group and submitted them to the lab. I found no diarrhea in a nursery of concern.
The next evening the diagnostic lab indicated both finisher barns were positive for TGE virus. They were started on oral electrolytes in the water and the rooms were warmed slightly.
During my visit to the finisher barns, I discovered that my client had hauled a load of market hogs to the packing plant the previous day, before hauling pigs from the nursery to the finishing barn with the same trailer. He had washed the trailer at the commercial truck wash before returning home from the packing plant. But due to the freezing temperatures that week, it is likely the trailer was contaminated by TGE virus at the truck wash and it froze on the trailer.
When the pigs out of the nursery were loaded onto the trailer, they became infected. But I wondered how the older finisher barn got infected. As it turns out, after delivering the pigs, my client decided to stop and check the older finisher barn on the way back home. Likely, some fecal contamination on his boots or clothing made its way into the barn, carrying the virus with it.
After this incident occurred, we discussed and implemented new biosecurity standards for the farm that impacted transportation and personnel procedures.
Case Study No. 2
This case involves a 600-sow, two-site, farrow-to-finish operation. The nursery and finisher are located one mile from the sow unit. The nursery rooms are operated all-in, all-out, but finishing is continuous flow. The farm is positive but stable for porcine reproductive and respiratory syndrome (PRRS) virus and positive for Mycoplasma pneumonia; production averages about 26 pigs/sow/year.
One evening in mid-January, the owner called in a panic, concerned about severe scours in one farrowing room that wasn’t responding to treatment. I visited the farm the next afternoon to investigate.
By the next morning, most litters of recent farrowings were showing signs of watery diarrhea and high mortality. Many of the pigs were vomiting. Most of the sows were off feed and some had fevers of 104°F. The other two farrowing rooms were mildly affected. Few sows were off feed and diarrhea of the piglets was mild and scattered.
I collected some tissues from the dead piglets and fecal samples from the sows. Next-day lab results confirmed TGE virus in the pigs.
I recommended the producer collect fecal material and intestinal contents from several dead pigs to make an oral feedback mixture for distribution throughout the sow herd. All breeding animals received this mixture, which was repeated for three days. The purpose was to get all animals exposed to the virus quickly and generate immunity.
We then went into the farrowing house the next day and weaned all surviving piglets down to 10 days of age and moved them to the nursery.
Discussing possible methods of exposure with the client, it was apparent that a recent 2-in. snowfall had caused an increase in bird traffic around the entrances of the buildings. It is likely some of the droppings had TGE virus in them and was tracked into the building by the farm staff. I discussed with the owner an expected outcome of the disease break and the likelihood that most of the new piglets born for the next two weeks will have low survivability.
After that point, piglet survivability should rapidly increase as sows start protecting the pigs through colostral maternal antibodies. All new gilt introductions to the farm were halted as well. The farm production is expected to be back to normal within a couple of months.
Don’t overlook other diseases that can be a significant economic threat to swine farms. Diseases like TGE are not part of everyday conversations in today’s pig production circles, but are certainly present in the assortment of diseases confronting pig operations.
Design improved biosecurity programs and minimize bird traffic around barns, especially during winter months.
Discuss with your veterinarian methods to guard against exposure to diseases like TGE.