Observations on histamine, serotonin, cortisol and cortisol binding globulins in bovine anaplasmosis.

Changes in histamine, serotonin, cortisol and cortisol binding globulin (CBG) levels were observed in Anaplasma marginale-infected bovine calves. In addition, packed cell volume (PCV), platelet number and percentage parasitaemia were also recorded. The whole blood histamine and serotonin values rose significantly (P less than 0.01 and P less than 0.025, respectively) during the acute stage of Anaplasma infection. Higher serum cortisol and CBG levels (P less than 0.05) were observed in acute and carrier infections, respectively. A sharp drop in thrombocyte count (59%) and PCV (33%) was also noticed in clinical anaplasmosis. The results suggest that the higher levels of biogenic amines which are known to produce increased vasodilation, capillary permeability and tissue anoxia and hypercortisolaemia to protect animals from stress and cell damage may play a similar role in the pathogenesis of acute anaplasmosis.