title: Urinary and faecal N-methylhistamine concentrations do not serve as markers for mast cell activation or clinical disease activity in dogs with chronic enteropathies.
abstract: BACKGROUND
  This study sought to correlate faecal and urinary N-methylhistamine (NMH) concentrations with resting versus degranulated duodenal mast cell numbers in dogs with chronic enteropathies (CE), and investigate correlations between intestinal mast cell activation and clinical severity of disease as assessed by canine chronic enteropathy clinical activity index (CCECAI), and between urinary and faecal NMH concentrations, mast cell numbers, and histopathological scores. Twenty-eight dogs with CE were included. Duodenal biopsies were stained with haematoxylin and eosin (H&E), toluidine blue, and by immunohistochemical labelling for tryptase. Duodenal biopsies were assigned a histopathological severity score, and duodenal mast cell numbers were counted in five high-power fields after metachromatic and immunohistochemical staining. Faecal and urinary NMH concentrations were measured by gas chromatography-mass spectrometry.
  
  
  RESULTS
  There was no correlation between the CCECAI and faecal or urinary NMH concentrations, mast cell numbers, or histopathological score - or between faecal or urinary NMH concentration and mast cell numbers. Post hoc analysis revealed a statistically significant difference in toluidine blue positive mast cells between two treatment groups (exclusion diet with/without metronidazole versus immunosuppression (IS)), with higher numbers among dogs not requiring IS.
  
  
  CONCLUSIONS
  Faecal and urinary NMH concentrations and duodenal mast cell numbers were not useful indicators of severity of disease as assessed by the CCECAI or histological evaluation. The number of duodenal mast cells was higher in dogs that did not need IS, i.e. in dogs responding to an exclusion diet (with/without metronidazole), than in dogs requiring IS. Further studies comparing the role of mast cells in dogs with different forms of CE are needed.
authors.affiliation: Department of Veterinary Clinical Sciences, Royal Veterinary College, University of London, Hatfield, AL9 7TA, England. kristin.anfinsen@nmbu.no.|Current address: NMBU School of Veterinary Science, Department of Companion Animal Clinical Sciences, Norwegian University of Life Sciences (NMBU), Box 8146 Dep., N-0033, Oslo, Norway. kristin.anfinsen@nmbu.no.
authors.forename: Kristin P
authors.initials: KP
authors.lastname: Anfinsen
authors.affiliation: Gastrointestinal Laboratory, Department of Small Animal Clinical Sciences, College of Veterinary Medicine, Texas A&M University, College Station, TX, 77843-4474, USA. nberghoff@cvm.tamu.edu.
authors.forename: Nora
authors.initials: N
authors.lastname: Berghoff
authors.affiliation: Department of Pathology & Pathogen Biology, Royal Veterinary College, University of London, Hatfield, AL9 7TA, England. spriestnall@rvc.ac.uk.
authors.forename: Simon L
authors.initials: SL
authors.lastname: Priestnall
authors.affiliation: Gastrointestinal Laboratory, Department of Small Animal Clinical Sciences, College of Veterinary Medicine, Texas A&M University, College Station, TX, 77843-4474, USA. jsuchodolski@cvm.tamu.edu.
authors.forename: Jan S
authors.initials: JS
authors.lastname: Suchodolski
authors.affiliation: Gastrointestinal Laboratory, Department of Small Animal Clinical Sciences, College of Veterinary Medicine, Texas A&M University, College Station, TX, 77843-4474, USA. jsteiner@cvm.tamu.edu.
authors.forename: Jörg M
authors.initials: JM
authors.lastname: Steiner
authors.affiliation: Department of Veterinary Clinical Sciences, Royal Veterinary College, University of London, Hatfield, AL9 7TA, England. kallenspach@rvc.ac.uk.
authors.forename: Karin
authors.initials: K
authors.lastname: Allenspach
mesh_terms: D000818:Animals; D015415:Biomarkers / Q000032:analysis; D015550:Cell Degranulation; D002908:Chronic Disease; D004283:Dog Diseases / Q000473:pathology* / Q000503:physiopathology*; D004285:Dogs; D005260:Female; D007410:Intestinal Diseases / Q000473:pathology / Q000503:physiopathology / Q000662:veterinary*; D008297:Male; D008407:Mast Cells / Q000502:physiology*; D008761:Methylhistamines / Q000378:metabolism* / Q000652:urine
chemical_list: D015415:Biomarkers; D008761:Methylhistamines; C048140:N-methylhistamine