SOW lameness compromises sow welfare, reduces sow productivity and longevity and, ultimately, reduces the efficiency and profitability of any sow herd.

It is also one of the most common reasons for culling sows after reproductive failure, according to a report by Dr. Yolande Seddon of the Prairie Swine Center in Saskatchewan.

"Sow lameness is a problem that has always been within the industry, yet little is known about the prevalence and severity of sow lameness within herds," Seddon noted.

Currently, it is estimated that 8-15% of the sows culled are removed for lameness, but the range varies from 0% to 39% among farms. It is believed, however, that the true prevalence of lameness is higher since it often remains undetected until the sow's condition deteriorates.

According to Seddon, a detailed survey of one Canadian herd found that 60% of sows displayed an abnormal gait.

Causes of lameness

The causes of lameness are often multifactorial, which can make it a challenge to address and to treat individual cases with success, Seddon explained.

Common causes of lameness include: conditions affecting the structure of the joints (osteochondrosis, osteoarthritis and arthritis), conformation problems leading to weakness in the legs, injury and trauma (particularly from flooring), hoof lesions and osteomalacia (weakening of the bones, particularly after the mineral demands of lactation).

Seddon said injury and trauma are believed to be major causes of lameness in sows and may become a more significant problem as the industry moves to group housing, particularly with the use of bedding-free systems, which is widespread in Canada.

Being aware

"Knowledge of the extent of lameness within a herd is a first step to understanding the problem, from which solutions can be developed," Seddon noted.

Culling and mortality records are a useful start, she said, but on-farm monitoring of sows is more important as it will contribute to earlier detection of lameness, which is key to minimizing losses.

"Currently, the best method for practical on-farm monitoring of lameness is to observe sows as they walk," Seddon said.

Timely, consistent observation of sows should become part of the regular management routine to detect locomotion problems as they develop. As a subjective method, Seddon recommended that staff be given training in order to create consistency and explained that using a simple scale (e.g., zero to three) makes monitoring easier.

"Any time that sows are moved around the barn provides an opportunity to observe sow locomotion," she said, adding that observing locomotion specifically when moving a sow from gestation into farrowing is particularly revealing because lameness may become more pronounced when a sow is heavier.

"Further observation as the sow is moved to breeding is also beneficial to detect any problems that have developed in farrowing and indicate the need for review of the sow prior to breeding," she added.

Seddon said group housing systems provide plenty of opportunities to observe sows' locomotion throughout gestation.

"Close observation of sows after mixing should be performed to ensure no lameness has developed from injury after fighting," she said. "Records of sow locomotion score and injury should be kept, similar to production records, and these can help to show patterns in lameness development within the herd."

Taking action

Once lame sows are identified, they need to be dealt with quickly to ensure sow welfare and to minimize production losses, Seddon explained. Culling is likely the only option for severely lame sows, but milder cases may be worth treating. Sows that don't respond to treatment should be culled, she added.

Research on effective treatments for lame sows is limited. Also complicating treatment, Seddon said, is the fact that it can be hard to determine the cause of lameness in each case. "Thus, where lameness problems exist, investigation with the herd vet should be performed to try to determine the most common causes, helping to characterize symptoms and tailor treatments," she said.

Providing lame sows with two doses of a non-steroidal anti-inflammatory, a rubber mat and a corrective hoof trim to restore hoof conformation at eight weeks of gestation can significantly reduce the number of sows showing lameness and the severity of lameness observed in sows. However, the cost versus benefit of any treatment methods and the continued longevity of the sow in the herd need to be investigated, Seddon said.

"Certainly, to help improve the chances of lame sows recovering, those that are not coping in the home environment should be removed to a hospital pen," she added.

Providing a cushioned surface such as sawdust, straw or properly secured rubber matting can help alleviate pressure on the legs of the sow, she explained.

When young animals develop problems early, Seddon said this suggests a need to review management of replacement gilts for nutrition, handling, flooring, genetics and selection criteria.

"Good flooring is essential to prevent injury at all stages of production," she noted.

When poor flooring is believed to be a contributing factor, such as a slatted floor with inappropriate gap width, in the long term, it needs to be replaced.

"To help alleviate problems occurring with group-housed animals, refraining from mixing animals on the poor-quality flooring can help to reduce injury," Seddon suggested. "Instead, provide the animals with a solid footing for mixing — preferably bedded — and move to the gestation pen two to three days later."

PEDV disinfectant

A recent pork checkoff-funded study conducted at Iowa State University concluded that accelerated hydrogen peroxide (AHP) disinfectant inactivated porcine epidemic diarrhea virus (PEDV), even in feces found in swine trailers.

Dr. Lisa Becton told Feedstuffs that the National Pork Board's "Swine Health Committee wanted to fund research that was practical and immediately usable. Looking at products in cold weather fit the goal."

Harsh winter weather conditions make it difficult to completely dry pig transport trailers. According to Becton, the key to the study was the fact that it mimicked the harsh real-life conditions that challenge producers in the winter.

The study concluded that when it is not possible to wash, disinfect and dry the pig transport trailer, producers have another option to defend against PEDV.

The study evaluated the effectiveness of AHP disinfection. The product, also known as Accel, was applied to inactive PEDV in feces that had been spread evenly across the bottom of 6 in. x 6 in. aluminum trays designed to replicate the floor of a livestock trailer.

Ten trays in the control group were cooled in a 4°C refrigerator to imitate cold weather. The chilled trays were treated with a variety of levels of the AHP disinfectant and tested in feces laced with either 5 mL or 10 mL of PEDV-positive feces.

Tests were conducted with 1:16 and 1:32 concentration levels of AHP applied in a 10% propylene solution and tested for both 40 minutes and 60 minutes.

Following treatment, the contents of the trays were collected and administered to four-week-old pigs via gastric tube. These pigs served as a bioassay to detect the presence of infectious PEDV after treatment.

Fecal swabs were taken three and seven days post-challenge and tested for the presence of PEDV via polymerase chain reaction to determine if the material from the trays infected the pigs. Pigs in each treatment group were housed separately in raised tubs within the same room.

The study's results, recently released by the Iowa State researchers and the pork checkoff, indicated that when mixed with propylene glycol, AHP effectively inactivates PEDV in both heavy and light feces in freezing conditions.

"The study indicates that there are options, but the best option to defend against PEDV is still to thoroughly wash, disinfect and dry livestock trailers," Becton said.

Industry stakeholders seeking more information about the study may contact Becton at [email protected].

Volume:87 Issue:12