Brent Jones from Southwest Ontario Veterinary Services, Looking Upstream For Salmonella

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The role that the breeding herd can play in setting up a growing pig population for Salmonella disease has  not  been  well  defined.  Field  studies  on Salmonella infection in suckling piglets are few and far  between.  As  you  can  imagine  it  is  not  easy  to obtain large numbers of the ideal diagnostic samples such  as  tonsils  or  mesenteric  lymph  nodes  from weaned  pigs.  Most  studies  rely  on  rectal  swabs. These researchers had access to the intestinal tracts of 495 4 week old weaned pigs that were being sold for human consumption. These pigs came from five Salmonella-seropositive breeding farms.

The findings from this study were as follows:

  • prevalence  of  both  infection  and shedding  was high (≈ 36%) Major  serotypes  found  in  piglets  included  4,[5],12:i:  (35.4%),  Rissen  (17.1%),  Derby (10.9%) and Bovismorbificans (10.3%).
  • In 72.8% of the infected pigs the same serotype was found in mesenteric lymph nodes and feces.
  • Significantly  higher  ELISA  OD%  values  were found in meat juice samples from non-infected piglets compared to infected ones (median OD% of  12.0  and  17.3,  respectively;  P  =  0.002) suggesting  some  protective  effect  of  sow’s colostrum.
  • Salmonella  was  also  isolated  from  feces  from weaned  sows  contemporary  of  the  slaughtered piglets,  and  89%  of  the  serotypes  identified  in sows were also detected in piglets
  • Pulsed field gel electrophoresis analyses showed that  75%  of  the  piglet  isolates  that  were compared to those of sows were related to them, suggesting the circulation of Salmonella strains between sows and piglets.

Take Home Message

  • Piglets are an important component of on farm Salmonella maintenance.
  • A  disease  control  plan  for  Salmonella  in  the growing pig should include an assessment for the  potential  to  reduce  infective  pressure that arises at the sow herd.

 

Submitted by Brent Jones, DVM

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