Effect of oral melatonin administration on inflammatory cytokines and acute phase proteins after the castration of dogs

Melatonin has been used perioperative to control pain, inflammation, and oxidative stress. The present paper aims to evaluate the effect of the administration of melatonin on acute phase proteins and inflammatory cytokines and compare the trends after the melatonin administration in intact and castrated dogs. Twenty healthy mature male dogs (1–3 years old) were divided randomly into 4 groups (n = 5): melatonin, castrated and melatonin, castrated, and control. Melatonin (3 mg capsule/10 kg) was administrated every 24 h for 1 month and castration was performed on day 0. Blood was collected from each dog’s jugular vein every 7 days during this period. The serum samples were tested for hormonal assay using ELISA methods. Proteins and inflammatory cytokines (α-1 acid glycoprotein (AGP), serum amyloid-A (SAA), C-reactive protein (CRP), interleukin-1β (IL-1β), and tumor necrosis factor-α (TNF-α)) usually elevated in the first few days after surgery and returned to normal about 7 days after the surgery. During the study, the use of melatonin in castrated dogs significantly reduced the inflammatory proteins and cytokines, but in intact dogs, it did not significantly change the proteins and inflammatory cytokines. Daily intake of melatonin capsules in dogs may be beneficial in reducing inflammation by affecting the concentration of proteins and inflammatory cytokines released after castration surgery.