There has been little work published concerning the effect of processing on the degradation of water-soluble B-vitamins in canned pet foods. The objectives of these experiments were to evaluate the effect of thiamine type (mononitrate vs hydrochloride), protein type (species meat and livers), and sulfite (yes or no) addition on B-vitamin retention. All diets were produced at a batter temperature of 60°C and moisture of 78%. The cook time was one hour at 121°C and 21psi. In Exp. 1 (n = 26) thiamine type tended (P = 0.12) to influence retention, wherein thiamine mononitrate retention (140.68 mg/kg) was higher than that of thiamine hydrochloride (128.37 mg/kg). In Exp. 2 (n = 14), protein type had an effect on retention of several B-vitamins. Thiamine retention was highest in fish relative to chicken or liver diets (P < 0.05; 202.26 vs 140.72, and 131.19 mg/kg, respectively). Riboflavin retention was highest in diets containing liver, intermediate with fish, and lowest for chicken (P < 0.05; 200.83, 153.46, and 113.66 mg/kg, respectively). Niacin was at its lowest retention in diets containing chicken compared with fish and liver diets (P < 0.0015; 238.42, 327.90, and 444.64 mg/kg, respectively). Pyridoxine retention was highest in diets containing fish versus those with liver or chicken (P < 0.05; 135.89 vs 113.34, and 100.59 mg/kg, respectively). Cobalamin retention was at its lowest in diets containing chicken, and intermediate for fish and highest for liver (P < 0.05; 0.45, 0.62, and 1.53 mg/kg, respectively). The addition of sulfites indirectly from dehydrated potatoes in Exp. 2 had a negative effect on pantothenic acid (P < 0.05; 234.80 mg/kg vs 360.29 mg/kg), and pyridoxine (P < 0.05; 108.02 mg/kg vs 134.34 mg/kg) relative to the controls, respectively. The dehydrated potatoes with sulfites tended to influence thiamine retention (P = 0.07; 137.80 mg/kg vs 188.22 mg/kg) and riboflavin retention (P = 0.09; 147.89 mg/kg vs. 188.25 mg/kg) relative to the control. Vitamin form, protein type, and presence of sulfites may influence their retention in canned pet foods.