title: Liquid chromatography-tandem mass spectrometry (LC-MS/MS) for analysis of endogenous steroids in the luteal phase and early pregnancy in dogs: a pilot study.
abstract: BACKGROUND
  Blood samples from dogs are often limited in volume, only allowing few steroids to be quantified with immunoassays. In addition, immunoassays may be compromised by interferences such as anti-reagent antibodies. Liquid chromatography-tandem mass spectrometry (LC-MS/MS) can be used for the simultaneous quantitation of several steroids. This has not been described in dogs before.
  
  
  OBJECTIVE
  The aims were to use LC-MS/MS to study steroid profiles in early pregnancy and luteal phase in dogs, and to determine if differences exist between pregnant (P) and nonpregnant (NP) dogs.
  
  
  METHODS
  Nine female dogs were included, 4 during a NP luteal phase, 4 during a P luteal phase, and one during one NP and one P luteal phase. Blood samples were collected around the time of the LH surge (Day 0) and on Day 26. Serum was analyzed for 5 classes of steroids, including glucocorticoids, androgens, estrogens, pregnanes, and progestins, using LC-MS/MS methods.
  
  
  RESULTS
  The concentration of progesterone was significantly higher on Day 26 in P than in NP bitches. Distribution of concentrations of glucocorticoids, androgens, estrogens, or pregnanes in P and NP dogs were not statistically different. The predominating glucocorticoid was cortisol, and dihydroepiandrosterone (DHEA) was the predominating androgen. Concentration of estrone was comparable to oestradiol, whereas concentrations of pregnenolone were higher than those of 17-OH pregnenolone.
  
  
  CONCLUSIONS
  Only concentration of progesterone differed between P and NP bitches, being significantly higher on Day 26 in P than in NP bitches. LC-MS/MS offers interesting possibilities for studies of canine reproductive endocrinology.
authors.affiliation: Department of Clinical Sciences, Swedish University of Agricultural Sciences, Uppsala, Sweden.|Centre for Reproductive Biology, SLU, Uppsala, Sweden.
authors.forename: Bodil S
authors.initials: BS
authors.lastname: Holst
authors.affiliation: ARUP Institute for Clinical & Experimental Pathology, Salt Lake City, UT, USA.|Department of Pathology, University of Utah School of Medicine, Salt Lake City, UT, USA.
authors.forename: Mark M
authors.initials: MM
authors.lastname: Kushnir
authors.affiliation: Department of Pathology, University of Utah School of Medicine, Salt Lake City, UT, USA.|Department of Chemistry - BMC, Analytical Chemistry and SciLife Lab, Uppsala University, Uppsala, Sweden.
authors.forename: Jonas
authors.initials: J
authors.lastname: Bergquist
mesh_terms: D000818:Animals; D002853:Chromatography, Liquid / Q000662:veterinary*; D004285:Dogs / Q000097:blood*; D005260:Female; D008183:Luteal Phase / Q000097:blood*; D010865:Pilot Projects; D011247:Pregnancy; D011270:Pregnancy, Animal / Q000097:blood; D013256:Steroids / Q000097:blood*; D053719:Tandem Mass Spectrometry / Q000662:veterinary*
chemical_list: D013256:Steroids
keywords: Androgen; glucocorticoid; laboratory analysis; progesterone; reproduction