Effects of medetomidine on serum osmolality; urine volume, osmolality and pH; free water clearance; and fractional clearance of sodium, chloride, potassium, and glucose in dogs.
OBJECTIVE
To determine effects of i.v. medetomidine administration on selected clinicopathologic variables in dogs.


METHODS
6 healthy adult Beagles.


METHODS
Dogs were randomly assigned to each of 3 treatments in a crossover study design. Serum osmolality, urine osmolality, urine pH, and fractional clearances of sodium, chloride, potassium, and glucose were determined before and 20, 40, 60, 120, 180, 240, 300, 360, 420, and 480 minutes after i.v. administration of 0.9% NaCl (saline) solution (control) or medetomidine (10 or 20 micrograms/kg of body weight). The urinary bladder was emptied prior to saline or medetomidine administration, and urine volume was determined at the same posttreatment times as those described previously. Free water clearance was calculated for all posttreatment times.


RESULTS
After medetomidine administration, serum osmolality, urine volume, free water clearance, and fractional clearance of potassium and glucose increased; urine osmolality decreased. Initially, urine pH and fractional clearance of chloride decreased, then subsequently increased. Fractional clearance of sodium did not change.


CONCLUSIONS
Because i.v. administration of medetomidine to dogs at dosages of 10 and 20 micrograms/kg induces a diuretic effect that lasts up to 4 hours, the drug should be used with discretion in hypovolemic or dehydrated dogs, and its use should be avoided in those with urinary tract obstruction.
Burton
S
S
Department of Pathology and Microbiology, Atlantic Veterinary College, University of Prince Edward Island, Charlottetown, Canada.
Lemke
K A
KA
Ihle
S L
SL
Mackenzie
A L
AL
D000316:Adrenergic alpha-Agonists / Q000008:administration & dosage / Q000494:pharmacology*; D000818:Animals; D001786:Blood Glucose / Q000378:metabolism*; D001834:Body Water / Q000378:metabolism; D002712:Chlorides / Q000097:blood / Q000652:urine; D018592:Cross-Over Studies; D004231:Diuresis / Q000187:drug effects; D004285:Dogs; D004573:Electrolytes / Q000097:blood* / Q000652:urine; D005260:Female; D006029:Glycosuria; D006339:Heart Rate / Q000187:drug effects; D006863:Hydrogen-Ion Concentration; D007093:Imidazoles / Q000008:administration & dosage / Q000494:pharmacology*; D007275:Injections, Intravenous; D008297:Male; D020926:Medetomidine; D009994:Osmolar Concentration; D011188:Potassium / Q000097:blood / Q000652:urine; D012964:Sodium / Q000097:blood / Q000652:urine; D014556:Urine / Q000737:chemistry*
D000316:Adrenergic alpha-Agonists; D001786:Blood Glucose; D002712:Chlorides; D004573:Electrolytes; D007093:Imidazoles; D012964:Sodium; D020926:Medetomidine; D011188:Potassium