Splay leg occurs worldwide in newborn pigs (swine). It effects are muscle weakness and difficulty standing.
- Causes of Splay leg >
- Effects of Splay leg >
- Diagnosis of Splay leg >
- Treatment & Control of Splay leg >
Causes of Splay leg
This important (up to 1.5%) congenital condition can have a genetic, nutritional, toxic or infectious cause. The commonest mechanism is an additive polygenic genetic trait with no clear evidence of dominance, especially in Pietrain, Landrace and Welsh pigs.
It appears to occur twice as frequently in males and a maternal effect has been identified, apparently mediated through larger litters which have affected more piglets and a shorter (0.9 day) period stationed.
Weakness of the legs causing the splaying is due to the presence of too few Type 1 Myofibril in the fibers of muscles of the foreleg, lumbar group and, most importantly, the hind leg. The condition appears to represent a failure of muscle fibers to mature in sufficient numbers to provide adequate support at birth.
The semitendinosus muscle is the most severely affected in the hind limb. Splay leg is more common in pigs born before 113 days of gestation, and infection, nutrition and early induction of farrowing using prostaglandins may all increase the numbers with splay leg. Zearalenone ingestion by the sow can cause splay leg in the litter.
Effects of Splay leg
Affected piglets are unable to stand, and are often found with a hind limb extended forward along the axis of the body with the opposite leg abducted (at right angles to the body).
They can move slowly by dragging themselves along by the front legs. If not killed by crushing and if able to feed, affected piglets become normal within 10 days of birth. Affected piglets may develop sores on the perineum (hind quarters) and erosion of the base of the tail. Up to 50% of affected piglets may die if not assisted. They are particularly prone to chilling. The condition becomes apparent 2-3 hours after birth and 2.3 piglets may be affected in each litter.
Diagnosis of Splay leg
The identification of splay leg is normally a matter of inspection of the litter when affected animals can be seen. The identification of the condition post-mortem is important as splay leg is a major contributor to pre-weaning mortality and must be identified.
Affected piglets usually have sores on the hind quarters and erosion of the base of the tail and are in poor condition with empty stomachs if unable to feed. The actual cause of death may be hypoglycaemia or crushing. The cause of the splay leg is normally genetic, but the possibility that it is associated with zearalenone toxicity should be investigated. If this is the case, it is likely that there will be a prominent vulval enlargement and udder in newborn piglets. Confirmation is by analysis of the feed.
Where PRRS infection during pregnancy has increased the numbers of piglets with splay leg, antibody is often present in sow sera and in still born piglets. Injudicious induction of farrowing with prostaglandin can be identified from the service, treatment and farrowing records.
Treatment & Control of Splay leg
Affected piglets should be kept warm and helped to take colostrum. They may be reared artificially for 2-3 days and returned to the sow. The use of Physostigmine has been suggested as an aid to recovery in piglets 12 hours or more of age.
Repeated massage of the hind limbs improves survival dramatically, but the commonest aid to survival is probably the practice of taping the hind limbs together or the use of elastic bands. This improves piglets' ability to stand and move around until the legs strengthen.
Non-slip floors may also improve footing and improve viability. The effects of zearalenone toxicity can be reduced by removing contaminated sow feed, but this takes up to 14 days to reduce the levels of zearalenone in milk and thus fostering or artificial feeding may be required to reduce mortality and aid recovery.
Crossing Welsh Landrace sows with Large White boars reduces the incidence. Farrow before day 113 should be avoided and management of PRRS to ensure that intrauterine infection does not occur is advisable.
