Urinary catecholamine and metadrenaline to creatinine ratios in dogs with a phaeochromocytoma

Urinary adrenaline (epinephrine), noradrenaline, dopamine, metadrenaline (metanephrine) and normetadrenaline to creatinine ratios were measured from spot samples of seven client-owned dogs with a histologically confirmed phaeochromocytoma. Urine was collected on day 0 in the hospital in six dogs, and additionally on days 2, 6 and 7 after discharge in two of these dogs. In one dog, urine was sampled on day 7 only. Samples were also collected from 10 healthy control dogs on days 0, 1 and 7. In dogs with phaeochromocytomas, normetadrenaline:creatinine ratios at all time points ranged from 103 to 6430 nmol/mmol. From day 0, ratios of samples taken at the hospital (range 157 to 925 nmol/mmol) were significantly higher (P<0.0012) compared with control samples (range 14 to 91 nmol/mmol). The highest normetadrenaline:creatinine ratios were found in two dogs with bilateral phaeochromocytomas. Adrenaline:creatinine and noradrenaline:creatinine ratios were also significantly increased (P<0.016) in dogs with a phaeochromocytoma at day 0 compared with controls, although the difference was less pronounced than that between controls and dogs with a phaeochromocytoma for the normetadrenaline:creatinine ratio. Urine normetadrenaline:creatinine ratios may be useful in the diagnosis of canine phaeochromocytomas.