Serum amyloid A and haptoglobin concentrations are increased in plasma of mares with ascending placentitis in the absence of changes in peripheral leukocyte counts or fibrinogen concentration

Am J Reprod Immunol. 2014 Oct;72(4):376-85. doi: 10.1111/aji.12278. Epub 2014 Jun 11.


Problem: Currently, placentitis, an important cause of late pregnancy loss in mares, is diagnosed by clinical signs and ultrasonography. Acute phase proteins (APP) are mainly produced and secreted by the liver in response to acute inflammatory stimuli. We hypothesized that APP are increased in mares with placentitis.

Method of study: Concentrations of serum amyloid A (SAA), haptoglobin (Hp), fibrinogen (Fb), and white blood cell counts (WBC) were determined in plasma of mares with experimentally induced placentitis and gestationally age-matched control mares. Placentitis was induced via intracervical inoculation of Streptococcus equi subspecies zooepidemicus, a common isolate from clinical cases of bacterial placentitis. Concentrations of SAA and Hp were also determined in the 10 days pre-partum in normal mares.

Results and conclusion: Mares with placentitis aborted within 5-25 days after inoculation. Concentrations of SAA and Hp rapidly increased subsequent to experimental induction of placentitis and remained increased until abortion. Neither Fb nor WBC appeared to be useful markers for placentitis. Parturition did not trigger increase in either SAA or Hp in normal foaling mares.

Keywords: Abortion; acute phase proteins; horse; pregnancy loss.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Acute-Phase Proteins / metabolism
  • Animals
  • Female
  • Fibrinogen / metabolism*
  • Haptoglobins / metabolism*
  • Horse Diseases
  • Horses
  • Inflammation / pathology
  • Leukocyte Count
  • Liver / metabolism
  • Placenta / pathology
  • Placenta Diseases / immunology*
  • Placenta Diseases / microbiology
  • Pregnancy
  • Pregnancy Complications, Infectious / veterinary*
  • Serum Amyloid A Protein / metabolism*
  • Streptococcal Infections / immunology
  • Streptococcus equi / pathogenicity


  • Acute-Phase Proteins
  • Haptoglobins
  • Serum Amyloid A Protein
  • Fibrinogen