When asked to give an update on swine flu, I first shuddered at the thought. Haven't we been inundated enough with inaccurate media coverage on swine influenza virus (SIV)?
I was thrilled, however, to watch a home video on YouTube put together by the kids of Chinn Family Farms, a Missouri farm family. It was refreshing to see common sense prevail as the kids request to “call It H1N1, please.” I would encourage everyone to view this 30-second video at the following web site: www.youtube.com; search for “Call it H1N1, Please,” Future Farmers 1.
Following are some real-life swine respiratory disease issues that I have recently faced.
Case Study No. 1
The manager of a 2,400-sow weaner pig farm was concerned about new gilts that were off feed, lethargic and feverish. The gilts were from a new genetic source, although several loads previously delivered had encountered no problems. Gilts were typically run through a 60-day isolation/acclimation protocol that included the use of a commercial SIV vaccine.
When I examined the animals, most were reluctant to get up, and several had their heads lying in the water troughs trying to cool off. The gilts were very gaunt, and occasionally one was thumping or had a dry cough.
No sows in the system were exhibiting any clinical problems, and the older gilts on the site were up, active and thrifty.
Two gilts were euthanized. I was concerned about the possibilities of Actinobacillus pleuropneumonia (APP) type 7, which had been diagnosed on the farm several years prior. There were no lesions consistent with APP Type 7, though. The lungs were wet and heavy, and when sliced had a foamy exudate from the cut. Samples submitted to the lab were confirmed positive for SIV type H1N2.
The gilts were injected with a long-acting prescription antibiotic and given oral aspirin. Over 10-14 days, several gilts came down with the same symptoms, although none died.
Upon further investigation, it was determined that the sick gilts received only one dose of commercial swine flu vaccine and had not received the booster dose. All the gilts within the herd that had received two doses of vaccine were clinically healthy.
As I have mentioned before in other articles, this case reiterated the importance of reviewing vaccinations and operating protocols on a regular basis.
Case Study No. 2
Shortly after arrival, single-source pigs in a 2,400-head, wean-to-finish barn exhibited a barking cough sounding like a “popcorn popper.” Most pigs were active, although one could find gaunt and thumping pigs.
Necropsies were consistent with a viral infection, as all lung lobes had a mottled appearance; secondary infections such as Streptococcus suis or Haemophilus parasuis (HPS) weren't observed. Diagnostic submissions confirmed SIV type H3N2.
Pigs were placed on oxytetracycline and aspirin orally in the water for five days. Gaunt pigs were injected with a prescription antibiotic. Other management procedures such as good air exchange and proper temperature settings for pigs were emphasized. This set of pigs recovered rapidly and had excellent closeout performance.
In this case, with single-source pigs in well-managed facilities, the occurrence of an early SIV outbreak appears to have minimal long-term effects on production performance.
Case Study No. 3
An 8,000-head, continuous-flow nursery with multiple sources of pigs exhibited a barking cough 10 days post-arrival. There was a high percentage of gaunt, fallout pigs. New sets of pigs entered this facility on a weekly basis. Pigs originated from multiple sow herds that had the same genetic source and were vaccinated identically.
Necropsy lesions, though, were quite different from the previous case study, as Bordetella bronchiseptica, Pasteurella multocida, strep and HPS were identified.
Multiple antibiotic injections and oral medications were utilized with poor results. Death loss typically ranged from 5-10%. Finishers continued to demonstrate high death loss and culls.
The primary difference between Case Study No. 2 and No. 3 was the presence of multiple sources in the latter. While trying to maintain similar sow herd immunity at each site, the variation in secondary organisms was different on each farm. SIV immunity may also have varied from farm to farm, resulting in different levels of maternal antibodies.
This system has quit mixing sources and is now filling nurseries with single-source pigs. Early indications are that these efforts will dramatically improve efforts to control SIV.
SIV can exhibit an array of symptoms, depending on the age and mix of pigs infected. Single-sourcing pigs and using commercial and autogenous vaccines can be helpful in controlling SIV even as new strains develop. Practice good hygiene with both people and pigs.