Experiments were conducted to investigate the effects of feed-borne ' Fusarium' mycotoxins on mature beagles, to test the protective efficacy of a polymeric glucomannan mycotoxin adsorbent (GMA), and to investigate the effects of 'Fusarium' mycotoxins on the canine serum proteome. Feed intake and body weight of dogs fed the contaminated diet were significantly reduced compared to controls. Significant reductions in blood pressure, heart rate, and serum concentrations of total protein, globulin, fibrinogen, alkaline phosphatase, and amylase as well as an increase in blood monocyte count were also detected. Dogs fed the contaminated diet + GMA exhibited significantly higher nutrient digestibility compared to controls, possibly due to the physiological adaptation to reduced feed intake. Significant changes in response to diets were detected in the canine serum proteome using SELDI-TOF-MS. It was concluded that the feeding of grains naturally contaminated with 'Fusarium' mycotoxins can adversely affect feeding behavior and metabolism of dogs.