Effect of phenobarbitone on the low-dose dexamethasone suppression test and the urinary corticoid: creatinine ratio in dogs
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Published on: April 25, 2016
S F Foster1, D B Church, A D Watson
1Department of Veterinary Clinical Sciences, University of Sydney, New South Wales.
Objectives:
To investigate potential effects of phenobarbitone on the low-dose dexamethasone suppression (LDDS) test and urinary corticoid to creatinine ratio in dogs in a controlled prospective study and in a clinical setting.
Animals:
Ten crossbreed experimental dogs and 10 client-owned dogs of mixed breeds treated chronically with phenobarbitone to control seizures.
Procedures:
Experimental dogs were allocated to treatment (6 mg/kg oral phenobarbitone, n = 6) and control (n = 4) groups. LDDS tests (dexamethasone 0.01 mg/kg intravenously, cortisol concentration determined at 0, 2, 4, 6 and 8 h) were conducted repeatedly over a 3-month period. Urinary corticoid to creatinine ratios were measured before LDDS tests. A single LDDS test was performed on 10 epileptic dogs.
Results:
LDDS and urinary corticoid to creatinine ratios in dogs were not affected by treatment with phenobarbitone.
Conclusions:
Phenobarbitone does not interfere with LDDS testing regardless of dosage or treatment time. Urinary corticoid to creatinine ratios are also unaffected.
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