An evaluation of serum prolactin in anxious dogs and response to treatment with selegiline or fluoxetine

Defining objective, reproducible and standardized parameters for the evaluation of patients is one of the main academic focuses of veterinary behaviour medicine. Prolactin, a peptidic neurohormone and a cytokine, whose main regulator is dopamine, seems to be of particular interest in relation to chronically distressed patients. The aim of this clinical study was to assess the correlation between prolactin levels in the blood (prolactinaemia) and chronic anxiety and to evaluate its value in helping to guide the choice of the most appropriate drug in dogs displaying emotional disorders. The inclusion criteria included an EDED score superior or equal to 10 and the absence of any previous treatment or physical condition, which could modify prolactin secretion or emotional reactions. After inclusion, a randomization number was assigned to the dog, with a preselected treatment: fluoxetine (1 mg/kg once a day) or selegiline (0.5 mg/kg once a day). Each dog was evaluated with a complete behaviour examination, a physical examination, EDED score and a blood sample to measure prolactinaemia.The dogs were re-evaluated 4 weeks, 8 weeks and 16 weeks later. The follow-up visits were organised the same way as the inclusion visit, including EDED scoring and prolactinaemia evaluation.A population of 84 dogs was enrolled in study. The analysis of the correlations between prolactinaemia and EDED score show a positive significant correlation.Evaluation of treatment follow up showed a statistically significantly greater improvement with selegiline in the dogs with higher levels of prolactinaemia compared to those with lower levels of prolactin, who were significantly more improved by fluoxetine.