Effects of exercise-induced stress and dexamethasone on plasma hormone and glucose concentrations and sedation in dogs treated with dexmedetomidine.
OBJECTIVE
To compare the effects of pretreatment with dexamethasone, physical stress (exercise), or both on sedation and plasma hormone and glucose concentrations in dogs treated with dexmedetomidine (DEX).


METHODS
6 healthy purpose-bred Beagles.


METHODS
Dogs received 4 treatments each in a randomized order prior to i.v. administration of DEX (5 fLg/kg). Pretreatments were as follows: (1) i.v. administration of saline (0.9% NaCI) solution and no exercise (control group); (2) IV administration of dexamethasone (0.05 mg/kg) and no exercise (DM group); (3) i.v. administration of saline solution and exercise (EX group; 15 minutes of trotting on a treadmill at a speed of 2 m/s); and (4) i.v. administration of dexamethasone and exercise (DM+EX group).


RESULTS
Following DEX administration, all dogs had similar times to recumbency and sedation index values, irrespective of pretreatment with values, irrespective of pretreatment with dexam-d ethasone or exercise. Plasma catecholamine concentrations decreased after DEX administration. Compared with control group dogs, plasma cortisol concentrations were higher in EX-group dogs prior to DEX administration and lower in DM- and DM+EX-group dogs following DEX administration. Administration of DEX decreased plasma cortisol concentration in EX-group dogs only. Plasma glucose concentration was not influenced by exercise or dexamethasone administration was lower than baseline concentrations at 30 minutes after DEX administration and returned to baseline values by 90 minutes. Heart and respiratory rates and rectal temperature increased during exercise. After DEX administration, these values decreased below baseline values. The decrease in heart rate was of shorter duration in dogs that underwent pretreatment with dexamethasone, exercise, or both than in control group dogs.


CONCLUSIONS
Pretreatment with dexamethasone, moderate physical stress (exercise), or both did not influence sedation or cause adverse effects in healthy dogs treated with DEX.
Raekallio
Marja R
MR
University of Helsinki, Faculty of Veterinary Medicine, Department of Clinical Veterinary Sciences, Helsinki, Finland.
Kuusela
Erja K
EK
Lehtinen
Milla E
ME
Tykkyläinen
Marja K
MK
Huttunen
Pirkko
P
Westerholm
Fia C
FC
D000818:Animals; D001786:Blood Glucose / Q000378:metabolism*; D002851:Chromatography, High Pressure Liquid / Q000662:veterinary; D003907:Dexamethasone / Q000494:pharmacology*; D020927:Dexmedetomidine / Q000494:pharmacology*; D004285:Dogs; D004359:Drug Therapy, Combination; D004837:Epinephrine / Q000097:blood; D005260:Female; D005938:Glucocorticoids / Q000494:pharmacology*; D006728:Hormones / Q000097:blood*; D006854:Hydrocortisone / Q000097:blood; D006993:Hypnotics and Sedatives / Q000494:pharmacology*; D007118:Immunoassay / Q000662:veterinary; D008297:Male; D009638:Norepinephrine / Q000097:blood; D010805:Physical Conditioning, Animal / Q000502:physiology*; D011863:Radioimmunoassay / Q000662:veterinary; D013312:Stress, Physiological / Q000378:metabolism; D014667:Vasopressins / Q000097:blood
D001786:Blood Glucose; D005938:Glucocorticoids; D006728:Hormones; D006993:Hypnotics and Sedatives; D014667:Vasopressins; D020927:Dexmedetomidine; D003907:Dexamethasone; D006854:Hydrocortisone; D009638:Norepinephrine; D004837:Epinephrine