title: The effect of hydration status on the echocardiographic measurements of normal cats.
abstract: BACKGROUND
  Diagnosis of cardiomyopathy of cats is based on 2-dimensional (2D) echocardiography. However, circulating fluid volume largely determines diastolic cardiac chamber dimensions, and reduced diastolic volume in other species results in what has been called "pseudohypertrophy of the ventricular myocardium."
  
  
  OBJECTIVE
  Altered hydration produces changes on 2D echocardiography that may confound the diagnosis or severity assessment of cardiomyopathy of cats.
  
  
  METHODS
  Ten normal colony-sourced mixed breed cats were included.
  
  
  METHODS
  Cats were examined by echocardiography at baseline and at completion of 3 protocols (volume depletion and maintenance-rate and anesthetic-rate IV fluid administration) applied in randomized crossover design with a 6-7 day washout period.
  
  
  RESULTS
  Volume depletion increased diastolic left ventricular interventricular septal (IVSd) and free wall diameter (4.5 +/- 0.4 to 5.8 +/- 0.6 mm; P < .001) with wall thickness exceeding 6 mm in 4 cats. Diastolic left ventricular internal diameter (LVIDd) decreased, and reduction in systolic left ventricular internal diameter (LVIDs) produced end-systolic cavity obliteration in 7 cats. Left-atrial-to-aortic-root ratio (LA: Ao, 1.4 +/- 0.2 to 1.2 +/- 0.1, P < .05) and left atrial area in diastole (LAAd) decreased with volume depletion. Maintenance-rate IV fluid administration increased LAAd and fractional shortening (FS%). Anesthetic-rate IV fluid administration increased LVIDd, FS%, LAAd, and LA:Ao ratios (to 1.7 +/- 0.1, P < .01), producing an LA: Ao ratio above normal limits in 6 cats. A systolic heart murmur developed with administration of fluid at maintenance (n = 1) and anesthetic rates (n = 6).
  
  
  CONCLUSIONS
  Altered hydration status produces changes in the echocardiographic examination of normal cats that may lead to an erroneous diagnosis of cardiomyopathy or mask its presence. Hydration status should be considered during echocardiographic examination in cats.
authors.affiliation: Veterinary Medical Teaching Hospital, School of Veterinary Medicine, University of California, Davis, CA, USA. f.campbell@uq.edu.au
authors.forename: F E
authors.initials: FE
authors.lastname: Campbell
authors.forename: M D
authors.initials: MD
authors.lastname: Kittleson
mesh_terms: D000818:Animals; D001798:Blood Proteins / Q000378:metabolism; D009202:Cardiomyopathies / Q000000981:diagnostic imaging / Q000662:veterinary*; D002371:Cat Diseases / Q000000981:diagnostic imaging*; D002415:Cats / Q000378:metabolism*; D018592:Cross-Over Studies; D003681:Dehydration / Q000000981:diagnostic imaging / Q000662:veterinary*; D004232:Diuretics / Q000494:pharmacology; D015150:Echocardiography, Doppler / Q000379:methods / Q000662:veterinary*; D005260:Female; D005665:Furosemide / Q000494:pharmacology; D006339:Heart Rate / Q000502:physiology; D006400:Hematocrit / Q000662:veterinary; D008297:Male; D011897:Random Allocation
chemical_list: D001798:Blood Proteins; D004232:Diuretics; D005665:Furosemide