A role for the sympathetic nervous system in sympathetically maintained pain?

Much is known regarding a good prognosis of acute kidney injury (AKI) is achieved with adequate, intensive, and early treatment, which leads to acceleration of the renal blood flow rate and associated urination. Low-dose dopamine (1 to 5 μg/kg bwt per min) is a treatment option for AKI in humans but remains controversial for use in horses because of the lack of extensive clinical trial data. A 19-year-old Westfalen horse gelding was referred to the Animal Medical Center with a 1-hour history of mild abdominal pain and anorexia after dressage exercise for 1 hour. Since elevated serum levels of blood urea nitrogen (BUN) and creatinine were found on days 4 and 5, the horse was diagnosed with AKI. In addition to basic hydration therapy with lactated Ringer's solution, we decided to use ultralow-dose dopamine because of the possibilities of the upregulation of dopamine receptors in the affected kidney and general large animal specificity of drug doses. Infusions with 0.04 and 0.02 μg/kg bwt per min for 1 hour on days 6 and 7, respectively, were effective in decreasing serum levels of BUN and creatinine accompanied with a diuretic effect. Thus, short-term infusion of ultralow-dose dopamine may be useful in controlling the renal blood flow rate and clinical conditions in horses with AKI.