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Pig Health - Leptospirosis in Pigs
Mark White BVSc LLB DPM MRCVS Infertility in sows can result from a wide range ofcauses, both of an infectious and non-infectiousnature.  The latter includes management factors,nutrition and environment.  Disease can play a role,although in the UKmany of the specific reproductivediseases either have never occurred or have beeneradicated e.g. Brucella suis, Aujeszky's Disease. PRRS, Parvovirus (PPV) and the vaginitis/endometritis(discharge) syndrome - associated with vaginalcontamination at or around service -  have probablybeen the most frequent infectious causes of infertility inthis country although changes in management systems- particularly the removal of stalls and tethers at the Fig 1 The demise of stalls and tethers has seen a
end of the 20th century - have coincided with a marked reduction in discharges associated with returns to
programmes have seen a marked reduction in PPV and to some extent PRRS, whilst an increasing use of Leptospiras are spiral bacteria, which are associated artificial insemination in the pig herd has reduced the with a wide range of diseases in many species.  One of spread of both specific and non-specific venereal the best known is L.icterohaemorrhagiae, the cause of Weils Disease in man, which is primarily carried by rats However, failures of conception leading to regular and and can be seen as a systemic disease in young pigs, irregular returns and later problems in pregnancy albeit sporadically. The dog Lepto - L canicola - can relating to mummification, abortion and poor quality of cause sporadic septicaemic disease in young piglets pigs born remain major features on many breeding pig L.pomona is a specific, severe cause of reproductive units and whilst management is often the primary loss in pigs (including abortion) but has never been culprit, in many cases other infectious diseases may be diagnosed in the UK.  In this country, L.bratislava (part implicated.  Porcine Circovirus type II has become of the Australis gp) may be the cause of a specific enzootic throughout the UK pig population and has disease pattern in sows but, unfortunately, tends to be been linked with reproductive failure in gilts and sows used as a bucket diagnosis for reproductive failure, producing a SMEDI like syndrome similar to PPV.  frequently without any diagnostic backup.
However, there remains considerable uncertainty as toits actual significance in the field.  Other primary The Disease
infectious agents that have implicated in reproductive L.bratislava is not associated with illness in pigs, its disease are Leptospira and Chlamydophila.
effects being restricted to reproductive damage.
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Fig 3 Late mummification can be a feature of
Leptospira (1:6)
Confirmatory diagnosis is difficult to achieve. Demonstration of the organisms by fluorescent Fig 2 Discharging prior to return to service may be a
feature of Leptospira infection
antibody test (FAT) in aborted material or in thereproductive organs of culled sows provides strong The signs seen can include:- evidence of its involvement.  Serology is confusing.  1) An elevation in returns to service both at regular Where a recent infection has occurred, the MA titres 3 week intervals and at abnormal times (e.g. 28-35 will rise dramatically (into the thousands) but will fall days post service).
rapidly (within weeks).
2) Mucopurulent discharges may occur 2-3 days It is common practice to blood sample a herd before the sow demonstrates a return to oestrous.
suffering reproductive failure and find titres of 1:50,1:100 or even 1:200 in some animals.  It is very 3) Abortions may occur, particularly in late dangerous to assume any significance in such results.  Low level titres may be present in the 4) Increase in weak pigs born, stillbirths and normal herd and there is some degree of cross mummification are also typical features of a true reaction with the many other serotypes present in and around the pig farm, particularly in rodents and 5) Where confirmed cases do occur, they are other wildlife (hedgehogs, foxes, badgers etc) to frequently seen in established herds affecting gilts which obviously the outdoor herd is frequently only, suggesting that sows have some immunity.  L.
bratislava may occasionally be implicated in herd Caution should therefore be applied to interpreting infertility outbreaks affecting all ages of sows that last no more than a single herd cycle of five months.
- Sufficient samples should be taken.  A minimum 6) Some veterinarians and producers believe that L.
of six samples, and up to fourteen, should be bratislava can be the cause of long term cyclical taken for a herd screen where fertility problems infertility problems within herds but the definitive evidence to support such a belief id frequently - Sample sows when they abort or farrow with abnormal litters - not two to three weeks later asis needed for PRRS investigation.
- For herd screens, paired sampling (two to three weeks apart from suspicious animals) will revealchanging patterns.
- Widespread titres of 1:400 or more are suggestive of actual circulation of the bacteria,though even that in itself is not diagnostic.
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Despite a commonly held view, there is no evidence No vaccines are currently available in the UK to appearing in the spring and autumn.  This belief control L.bratislava, although they are available in seems to have arisen simply because such a Europe and can be imported by a veterinary pattern is seen in cattle affected with a totally surgeon under a Special Import Certificate. (Farrow different serotype - L.hardjo.
Sure B: Zoetis) Some UK based veterinary surgeons are strong believers in using such Where the disease is confirmed, herd treatment with antibiotics is appropriate.  This can take the Leptospira species with Erysipelas and PPV.  (Leptospira pomona vaccination is widely used inAustralia and New Zealand where this disease is of 1) Blanket herd injection as a single or double major significance.) treatment with streptomycin.
Other species can act as a reservoir of infection for pigs (e.g. rats and hedgehogs) but it must be streptomycin or potentiated sulphonamides.
remembered that the rats are not the primary 3) In feed medication with tetracyclines, although source - pigs are.  Rodent control should be a dose rate is important.  A dose of at least 10mg/kg priority in and around all pig farms.  The inevitable liveweight is needed and for large sows on low feed contact between outdoor pigs and hedgehog levels, this can require, for example, 10kg per tonne environments does create a risk of infection.
of 10% chlortetracycline premix.  Medication is Attention to hygiene in service areas is vital, needed from weaning until up to one-month post requiring regular washing and disinfection.  In service, although in practice it is often only practical outdoor units, care is needed with wallows that to treat the whole herd for a full sow cycle (five harbour infection.
months). In the interests of responsible use ofantibiotics this regime should only be pursued There is some circumstantial evidence that venereal based on sufficient evidence of the disease; the old spread is a major part of the development of the idea of treating the sow herd routinely say every disease and the exclusive use of AI is likely to be of 6mths for 1month is now regarded as inappropriate.
4) Regular treatment of boars (e.g. every 6 weeks) with streptomycin injection.   Use of preputial It is virtually impossible to state a specific cost of infusion using intramamary preparations off licence Leptospira infection in a herd.  In confirmed into the boars has been widely used historically but is of dubious value.
Over the years many herds have seen a positive - Herd outbreak lasting four months causing a response in sow fertility following the inclusion of depression in farrowing rate of 7% and reduction feed medication from weaning through to the post weaned per litter (as a result of reduced service period. Whilst this may be the result of livebirths and increased neonatal mortality) led control of Leptospira, in some cases it is not to a 300 sow herd suffering a drop in annual diagnostic.  Such responses may occur as a more production of 1.3 pigs per sow per year or 400 general effect of improved vaginal hygiene, by pigs less weaned.  At a marginal cost of £35 per controlling other undistinguishable pathogens (e.g.
pig, this implied a cost of £14,000.
Chlamydophilia) or purely by coincidence.
- A persistent problem in gilts reduced farrowing On an individual basis, chronically infertile sows (i.e.
rate in them by 11%, compensated by increased "double repeats") are best culled both on economic grounds and as potential disease carriers.
The use of feed medication in breeding rations has All treatments must be done under the direction of a often been applied to try and improve fertility but veterinary surgeon with strict observations of where used at the correct dose will add more than dosage rates and withdrawal period.
£30 to the cost of the diet and used over a sow Copyright NADIS 2016

cycle will add costs of £15 per sow - a notinsignificant cost if no response occurs.
For this reason and to comply with the generalprinciples of responsible use of antibiotics inanimals, medication of breeding sows for "fertility"reasons should only be undertaken where there isgood evidence that sensitive infectious agents areimplicated.
Leptospirosis in pigs is clinically over-diagnosed inthe UK sows.  Whilst it may be the cause of specificepisodes of reproductive failure and can beimplicated in long term herd infertility problems ingilts, it is wrong to assume that it is the cause of allepisodes of infertility with a knee jerk reaction toreach for medication.
information contained within this documentis accurate at the time of printing.
However, subject to the operation of lawNADIS accepts no liability for loss, damageor injury howsoever caused or suffereddirectly information and opinions contained in oromitted from this document.
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