title: Automated counting of nucleated cells in equine synovial fluid without and with hyaluronidase pretreatment.
abstract: BACKGROUND
  Microscopy is usually used to obtain manual total and differential cell counts in equine synovial fluid. A faster, more precise method is desirable.
  
  
  OBJECTIVE
  The objectives were to compare an automated impedance method with a manual method for obtaining total and differential cell counts in equine synovial fluid and to evaluate the effect of pretreatment with hyaluronidase on automated results.
  
  
  METHODS
  Synovial fluid samples (n=48) were collected into EDTA and analyzed within 48 hours. Automated total and differential cell counts were evaluated using a Medonic CA620-VET hematology analyzer before and after pretreatment for 5-30 minutes with hyaluronidase (final concentration 0.01 mg/mL). A hemacytometer count and microscopic evaluation of a direct smear were used as the reference method. Intra-assay coefficients of variation (CV) were determined.
  
  
  RESULTS
  Thirty-one of 46 untreated samples and 0/46 hyaluronidase-treated samples were error-flagged by the analyzer. Correlation between automated (ANCC) and manual (MNCC) nucleated cell counts in untreated samples (n=15; R(2)=0.93) and pretreated samples (n=46; R(2)=0.94) was high, and pseudomedian difference was low. Intra-assay CVs for samples with medium and high cellularity were significantly lower for ANCC (1.5-2.7%) compared with MNCC (6.1-15.7%) (P<.01). Valid automated differential cell counts were not obtained.
  
  
  CONCLUSIONS
  Automated total cell counts obtained on the Medonic analyzer correlate well with manual counts in equine synovial fluid; however, pretreatment with hyaluronidase is required to minimize error flags. Automated differential counts are not accurate for synovial fluid.
authors.affiliation: ATG Horse Clinic Ltd., Mantorp, Sweden. aekmann@hotmail.com
authors.forename: Anita
authors.initials: A
authors.lastname: Ekmann
authors.forename: Marie-Louise
authors.initials: ML
authors.lastname: Rigdal
authors.forename: Gittan
authors.initials: G
authors.lastname: Gröndahl
mesh_terms: D000818:Animals; D001331:Automation; D005434:Flow Cytometry / Q000295:instrumentation / Q000662:veterinary*; D006736:Horses / Q000378:metabolism*; D006821:Hyaluronoglucosaminidase; D012680:Sensitivity and Specificity; D013582:Synovial Fluid / Q000166:cytology*
chemical_list: D006821:Hyaluronoglucosaminidase