title: Dysgalactia associated with Mycoplasma suis infection in a sow herd.
abstract: METHODS
  A sudden onset of extreme dysgalactia in gilts and sows in a 1,000-head farrow-to-wean herd was observed in December 2009. Signs of dysgalactia were identified in sows beginning 1 day after parturition and lasted 4 to 6 days. This resulted in a mean piglet preweaning mortality rate of 18% because of starvation.
  
  
  RESULTS
  Sows were neither off feed nor febrile. Udders were not inflamed or congested. Feed sample analysis did not find ergotamine, mycotoxin contamination, or ration formulation errors. Management practices were acceptable. Piglets attempted to stimulate milk production but none was elicited. Oxytocin (20 U) caused milk ejection but the effect was short-lived. Blood samples from sows with affected litters were positive for Mycoplasma suis (formerly Eperythrozoon suis) by PCR assay, and blood samples from sows with unaffected litters were negative.
  
  
  RESULTS
  Chlortetracycline fed to the entire sow herd at 22 mg/kg/d (10 mg/lb/d) for 2 weeks resulted in a near complete absence of dysgalactia in sows farrowing within 5 weeks after the start of treatment. Dysgalactia did occur in sows that received chlortetracycline > 5 weeks prior to farrowing. Currently, gestating sows and gilts receive chlortetracycline in feed at a dosage of 22 mg/kg/d for 2 weeks beginning 3 weeks prior to farrowing.
  
  
  CONCLUSIONS
  M suis is spread primarily by blood contact from animal to animal, and diagnosis of infection with this organism can be easily missed by means of standard diagnostic protocols unless PCR assays or specific stains are used. Therefore, its current prevalence and impact are likely to be greatly underestimated.
authors.affiliation: Department of Veterinary Diagnostic and Production Animal Medicine, College of Veterinary Medicine, Iowa State University, Ames, 50011, USA. erin.strait@merck.com
authors.forename: Erin L
authors.initials: EL
authors.lastname: Strait
authors.forename: Peggy Anne
authors.initials: PA
authors.lastname: Hawkins
authors.forename: Warren D
authors.initials: WD
authors.lastname: Wilson
mesh_terms: D000821:Animal Feed; D000818:Animals; D000900:Anti-Bacterial Agents / Q000008:administration & dosage / Q000627:therapeutic use; D002751:Chlortetracycline / Q000008:administration & dosage / Q000627:therapeutic use; D005260:Female; D007774:Lactation; D009174:Mycoplasma / Q000302:isolation & purification*; D009175:Mycoplasma Infections / Q000473:pathology / Q000662:veterinary*; D011247:Pregnancy; D013552:Swine; D013553:Swine Diseases / Q000382:microbiology*
chemical_list: D000900:Anti-Bacterial Agents; D002751:Chlortetracycline