Look beyond disease for solutions to structural issues.
Most hogs are raised on some type of concrete flooring. These hard surfaces place structural demands on animals as they grow.
During a herd visit to a 1,400-sow, breed-to-wean unit, I expressed concern about the 13% sow mortality level occuring over the past six months. No necropsies were performed on sows during the six-month period.
The herd is PRRS (porcine reproductive and respiratory syndrome) virus-negative, but it is positive for Mycoplasmal pneumonia. The sow unit has gestation stalls plus a few pens for gilts and special needs sows.
The manager and I agreed to record the possible cause of any sow deaths over the next two months. I also asked to be notified of any sudden sow deaths so a necropsy could be performed.
After the two-month monitoring period, we discovered that half of the documented sow mortalities were due to lameness. Treatments had not been administered.
Eight sows were necropsied with only two demonstrating any signs of disease at time of posting. Tissue diagnostics demonstrated Streptococcus suis in multiple tissues on one sow and a gastric ulcer in the second.
To deal with lameness, we elected to merely change the sow treatment protocols. The breeding team was asked to walk the gestation barn immediately after feeding, examining the sows while standing. Any sow that was off feed or having difficulty standing was recorded so that a three-day treatment with injectable antibiotics could be administered.
Within 30 days of the start of this new program, sow mortality dropped to 8.7% and has remained under 8% since that time. The breeding staff became very familiar with identifying sows that showed signs of lameness, and they were eager to treat them. Their efforts were measurable and rewarding in improving overall sow health.
A finisher operation was purchasing 600 feeder pigs a week from a source that was PRRS virus-negative and Mycoplasma positive. The pigs receive a Mycoplasma and erysipelas combination vaccine at 5 and 7 weeks of age before arrival.
Most pigs flow into 1,200-head barns, plus two new 2,400-head, double-wide finishing barns. There have been very few disease problems in these barns.
Closeout information indicates an average mortality of 2.4% with less than 2% culls during the past 12 months.
One hot and humid June afternoon, the owner called to discuss the number of lame pigs he was treating in one of the new 2,400-head barns. The sort pen was filling up fast. Pigs weighed about 180-220 lb.
When I visited the site two days later, 5-10% of the pigs in each pen were limping and very lethargic. The owner commented, “The condition has deteriorated very rapidly during the past few days.” Several affected pigs would sit on their rear legs in a “dog-sitting” style, unwilling to move.
Death loss was normal, and there were no outward signs of disease. Pig temperatures were normal, and the rest of the group was very active. Floors were very wet in all pens.
Since the barn contained its first group of pigs, I examined the hooves closely for any evidence of cuts or abrasions caused by the roughness of new slats. None were found. I euthanized three pigs showing signs of lameness and sent tissues, including joint samples, to the lab.
Lab results were negative for bacterial growth on the joint tissues, but two pigs did show microscopic evidence of acute joint surface inflammation. One pig was found to have a Pasteurella multocida organism on the lungs.
In discussing the lab results with the owner, he indicated that no new cases of lameness had occurred in the past few days. The weather had moderated with daily temperatures in the low 80s.
I inquired about the cycle time of the misters in the barn. They had been set to run two minutes out of a 10-minute cycle. Since the weather had cooled off, the misters had not been in use, so the floors remained dry. The other barns in the system hadn't experienced the lameness cycle because the cycle time of the misters was set on running two minutes out of 25.
We concluded the two new barns had misters running too often, keeping the floors wet. The pigs were injuring themselves on wet flooring that made the slats very slippery.
Evaluating the cause of lameness and arthritic conditions in pigs can sometimes be difficult and frustrating. A complete diagnostic work-up, history and evaluation of the pig's environment are all important to resolving the problem. Consult with your veterinarian to develop a plan for determining causes of lameness in your production units.