Detecting, preventing and treating sow lameness

Awareness is the first step in addressing the problem of sow lameness. This process has to start with an assessment of reasons for culling sows, and sow replacement and mortality rates. It also helps to note whether sows being culled for reproductive/poor performance also are lame.

Sow heel erosion
Sow heel erosion

Awareness is the first step in addressing the problem of sow lameness. This process has to start with an assessment of reasons for culling sows, and sow replacement and mortality rates. It also helps to note whether sows being culled for reproductive/poor performance also are lame. Start keeping track of the number of sows with obvious clinical problems such as missing dew claws or external abscesses on their limbs. The farrowing house is a good place to do this. 

Routine claw lesion inspections

Research from Moorepark shows that irrespective of the gestation housing system, the majority of sows are affected by claw lesions. Incorporating routine claw inspections into a pig management program for breeding sows is an essential first step in addressing lameness. 

Indeed this will enable the pig producer to become familiar with different types of claw lesions and the anatomy of the foot. Routine inspections done in the farrowing house also will mean that the lesions can be monitored such that intervention happens early rather than later to prevent lameness from occurring. 

Lameness is much easier to identify in group housed sows compared to individually (i.e. stall) housed sows. This is true, provided that gilts and sows are not overstocked. Severe lameness is relatively easy to detect in any group system, and especially those sows that are fed simultaneously at specific times during the day. In such systems, sows are usually observed during feeding and animals that don't stand up or that have obvious difficulty moving to the trough at the point of feed delivery are clearly visible. 

Locomotion scoring

Detecting sows in the early stages of lameness are more likely to respond to treatment. This requires a more specific lameness protocol or locomotion scoring system. Visual locomotion scoring systems take the speed of walking and indications of asymmetry such as step length, head and hindquarter movements, willingness to walk and contact between the feet and the floor into account. They do not give any information as to the cause of lameness.

Sows should be locomotion scored when walking on a clean, dry and level solid surface (i.e. not on slats). A simple scoring system involves a four point scale where:

0 =       no lameness

1 =       mildly lame

2 =       moderately lame

3=        severely lame

A mildly lame animal moves freely but may appear stiff, a moderately lame sow exhibits shortness of stride or a "limp" but still bears weight on the affected limb. A severely lame sow does not bear weight on the affected limb and needs encouragement to move.

It is important to remember that lame sows will tend to move better immediately after weaning when their body condition is lighter so this is not a good time to diagnose lameness in the sow herd.

Preventing lameness

Clearly there are very good reasons why we should try to prevent sow lameness not least because the associated pain has negative implications for sow welfare. However, this is complicated by the fact that lameness is a multi-factorial problem with genetic, mechanical, chemical and biological processes involved. 

However, the risk factors for claw lesions are well understood. For example, improvements can be made to the housing environment such as replacing damaged slats or covering them with rubber and to management by ensuring that gilts have good claw conformation at selection and that sows and gilts are mixed in specialized pens which minimize the effects of aggression and protect the feet. 

Feeding trace minerals

Nutrition is vital in developing the hoof structure and the importance of the trace minerals manganese, zinc and copper in the keratinization process is well known. Hence, supplementing the diet with additional trace minerals helps to prevent lameness caused by claw lesions. 

Research shows that replacement gilts fed a diet supplemented with complex trace minerals had lower claw lesion scores and better locomotion scores compared to gilts fed an unsupplemented diet. Biotin is another essential component of hoof health. However, if biotin levels are too high the claws can become overgrown. It is best to check biotin levels in the sow diet with a nutritionist on a regular basis.

Dutch veterinarians recommend putting a tray filled with dry lime into the ESF station for sows to stand in while eating. The lime dries out and disinfects the feet every time the sow enters the station and this could help to prevent lameness.

Treating lame sows

Prevention is clearly better than a cure. However if sows become lame, they can recover with appropriate care and treatment. This is often lacking on many pig farms where the only "treatment"' is to cull or euthanize, the affected animal. Unfortunately such "treatment" is generally delayed until lame sows have farrowed meaning that suffering is prolonged.  

Typically we forget the tremendous investment of money, time and resources that are associated with bringing a replacement female into the herd. It may make better economic sense to try and keep a lame sow with good performance records in the herd by treating her rather than to introduce an unproven gilt in her place.

Lame sows and especially those with claw injuries (e.g. dew claw amputation) should be kept in a solid floored, bedded or rubber mat covered recovery pen where they do not have to compete for food and water. Depending on the condition, treatment may involve antibiotics, but lame sows should always be treated with anti-inflammatory drugs to improve chances of recovery. 

The use of analgesics (pain killers) such as aspirin in powdered form may be a useful adjunct therapy. The pain relief they provide encourages sows to get up, walk around and to eat and drink thereby speeding up their recovery. The surface of exposed, cleaned lesions may be sprayed with antibiotic, e.g. tetracycline, or dusted with an antibiotic wound powder. 

Culling should not be delayed for sows that do not recover following the treatment outlined above. Sows that have great difficulty walking or that are clearly in a lot of pain should not be sent to slaughter but instead euthanized as soon as possible.

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