Lameness is a swine production issue that all hog farms encounter. Feet and leg unsoundness will never magically cure itself over time. While the cause can vary, it becomes not only an important area of focus for an animal’s well-being, but also a reoccurring problem that can cripple profits by affecting viability, growth and reproduction of pigs.
Reducing lameness in the herd takes focus, says Jim Lowe, DVM, Integrated Food Animal Medicine Systems at the College of Veterinary Medicine, University of Illinois. When it comes to lameness, producers often think the problem is in the foot, but a closer look reveals that it is actually in the upper leg, Lowe notes.
It is crucial to be diligent in selecting the breeding herd. “If I get the feet and legs right in the breeding herd, I eliminate many problems in finishing pigs,” Lowe says.
He has been working hard with hog farmers to think differently about selection and be really critical of peer animals at the top of the genetic pyramid. Lowe notes, “It is a long process to start at the top. You have to spend the time every week when selecting gilts. You have to be diligent about what you are selecting.”
Choosing the right animal for the breeding herd starts with a clear vision. Lowe says the most successful farms have developed a well thought-out plan prior to the start of the selection process. Selecting for a single trait is never a good plan, warns Lowe. A large part of constructing the “selection plan” is defining the ideal balanced female with good feet and legs, good underline, good vulva and good performance. In addition, the weight of each trait on the decision process needs to be determined. The plan needs to be clearly communicated with every individual involved in the selection process to be consistent from week to week.
In a commercial setting, Lowe explains that it really comes down to anti-selecting. If you need to select 70 gilts from a group of 100, the best place to start is with the worst animal. Nevertheless, employees need to have an agreed understanding of what the worst animal is. At the end of the day, Lowe says it needs to be a “conscious, balanced approach” for gilt selection.
Katie Sinclair and Greg Gildorf, Genesus Genetics Inc., say as a genetics company, their commitment has always centered around providing pigs with strong genetic performance and overall good conformation of the animal. Sinclair further explains “When we are looking at females, we want overall good conformation, a well-balanced animal — and a big key component of that is strong feet and legs.”
A change in modern production housing will also affect female selection for the herd. Sinclair says if a hog farm switches to a more alternative method of housing, then there is going to be more of an emphasis on sound structure. She notes the goal is always to have a female with good sound structure, but alternative housing systems change the dynamics of what a producer looks for in a female that will no longer be standing in a stall setting. She says, “If you are not internal multiplication, you are hopefully working with a genetics company that has a sophisticated genetic improvement program, but also an emphasis on matching that with the actual conformation, of which feet and legs are important.”
Still, Sinclair and Gildorf point out that producers need to keep it simple when selecting soundness in the breeding herd. It all comes down to the basics. Gildorf says that the same principle for visually selecting sound females applies, but it is more critical to get it right these days.
Visually, the gilt needs to be sound from the beginning because that is one characteristic that will not improve over the animal’s lifetime. When evaluating the structure, the female should not be too straight at the hocks, with a proper angle of shoulder (see Figure 1). It is important to make sure the pig’s toes are even and the animal stands on them square. Furthermore, the female needs to be stouter-made and standing on a substantial bone structure that will be able to handle weight as it grows. Thickness of bone has become crucial, since hogs are being fed to heavier weights. These traits are also important because soundness is highly hereditable, Gildorf says.
Sinclair suggests if you are working with a genetics company, you need to ask what the genetic improvement program is and what the selection process is. For Genesus, the company has geneticists who look at the data and do match mating. However, a large part of their program is team members with their eyes and ears in the barn, visually checking if those match matings are ideal for conformation. Sinclair says it is important that an animal is good phenotypically along with the numbers.
Just as important as conformation on the selection process is disposition, reminds Sinclair. Don’t forget the personality of that pig is going to contribute to the success of your operation. Overall, a naturally low-stress animal will be beneficial, especially as the modern production practices evolve. For instance, Sinclair says animals in antibiotic-free systems tend to tail-bite more. So if you have animals that are not as easily stressed and are not prone to fight, then you can diminish future injuries.
On the sow farm, lameness is often found at farrowing, but in reality it probably happened long before that, Lowe explains. In the breeding herd, hog producers habitually breed sows or gilts that they know will become lame. This is the reason Lowe highly recommends that feet and leg structure needs to be evaluated at the time of breeding, so the wrong ones do not get bred.
The best time to evaluate a sow is in the gestation stall early in the morning when she is standing to eat, says Lowe. It is important to go down the line and critically evaluate those sows to determine who is equally standing on all four legs.
In years past, examining the sow’s gait and utilizing a gait scoring system to evaluate locomotion problems was a method of choice. However, research in the lab at Iowa State University shows a high degree of variation in gait exists from one sow to another, which makes it difficult to uniformly evaluate animals. Lowe says this scoring system works best for cattle, but not swine. On the practical side, he says it is best not to make it too complicated. If an animal cannot put equal weight on all four legs, then that is a good indication that something is not right. If animals are wobbling while just standing to eat, then it is probably not smart to invest the resources or the time in breeding them. Culling those animals could prevent larger problems down the road.
Alternative sow housing will only highlight structural soundness problems. Lowe says, “If you breed the right animal, group housing is fantastic. If they breed the wrong animals, group housing exposes all of our stupidity.” The only difference between individual gestation stalls and group housing is the sow becomes lame at different times. Honestly, Lowe says, it comes down to evaluating for soundness and other desirable traits at breeding.
While consciously selecting the correct breeding animals can eliminate some of the locomotion problems in growing pigs, lameness can occur for other reasons on the finishing floor.
Diagnosing lameness is not an easy task and can be multifaceted, since it can involve bones, muscles, tendons, nerves and blood supply of the shoulder, hock, stifle, foot, toe or hoof individually or in combination. Locke Karriker, DVM and Swine Medicine Education Center director at Iowa State University, in conjunction with National Pork Board, developed a decision tree for investigating lameness (see Figure 2) to assist producers. The decision tree serves as a good guide for identifying lameness and walking users through cognitive judgments when dealing with locomotion problems in the swine herd.
Once lameness is suspected, it is crucial to determine if it is an individual animal case or multiple animals are affected at nearly the same time. While traumatic injury is the most evident cause of lameness, it also can be triggered by infections or underlying metabolic diseases. If multiple animals with severe lameness are found, then the movement of animals should be halted, and a veterinarian needs to be consulted.
Lowe says lameness can be a byproduct of infection in the nursery. When pigs get sick with Streptococcus suis or Mycoplasma hyorhinis at a young age and then recovers, the chronic arthritis in the joints shows up at 180 pounds when the joint is bearing more weight. The pain is not obvious in a young pig, but becomes apparent over time. Unfortunately, treatment for chronic arthritis is not effective in a 180-pound pig. It has to be addressed in the nursery at the time of infection.
A large number of finishing pigs still exhibit osteochondrosis because of fast growth. OCD effects all species, including humans. Animals, and people grow fast increases the risk of OCD. Lowe points out that it is not feasible in the swine business to select for slow growth, so it is important to understand and how to minimize the risk of OCD in finishing hogs.
The lesion itself that occurs from OCD is not the sole problem, only when the joint experiences trauma does OCD cause clinical signs. The lesion will heal if it is not traumatized. Every time we truck or mix pigs there is a risk of joint trauma. Good animal handling, quality loading chutes, good trailers, minimizing the number of time animals are moved and avoiding mixing are all critical to minimize the impact of OCD in growing pigs. Correct diagnosis requires lab submission of the ends of long bones (i.e. fermur). If your farm has a huge OCD problem, then it is time to re-evaluate the transportation and loading practices of the operation from the trucks to the ramps to the pig-handling techniques.
“It really comes down to good stockmanship,” says Lowe.