Animal proteins, such as poultry by-product meal (PBM), are commonly used in extruded dog foods. Plant-based proteins have a more consistent nutrient profile than animal sources but may contain anti-nutritional factors (ANF), including trypsin inhibitors and oligosaccharides. The test protein, HP 300, is a proprietarily processed soy-based product with very low ANF concentrations and high nutritional value. The objective was to evaluate if HP 300 can be an effective PBM replacement in pet food and if there are practical limits to its use. We tested the effects of 0% (control), 4%, 8%, 12%, 24%, and 48% HP 300 on apparent total-tract macronutrient digestibility, fecal characteristics, and fecal fermentative end products in healthy adult dogs. All 6 diets were formulated to meet AAFCO nutrient profiles with approximately 30% crude protein and 16% fat. Forty-eight healthy adult beagle dogs (20 females, 28 males; mean age: 3.4 y; mean BW: 10.0 kg) were studied in a completely randomized design. The treatment period consisted of a 10-d diet adaptation phase followed by a 4-d fresh and total fecal collection phase. Stool output (both on as-is and dry matter basis [DMB]) did not differ from control until 48% HP 300 (P < 0.01). Fecal output per unit food intake (DMB) differed (P < 0.01) from control only at the 24% and 48% HP 300 inclusion rates. Notably, no effect of HP 300 inclusion was found for stool consistency scores. Digestibility of DM, organic matter and energy did not differ from control at any inclusion rate, except for a decrease (P < 0.01) at 48% HP 300, which is likely due to increased dietary fiber concentrations. Crude protein digestibility was not affected by treatment and ranged from 82.9 – 86.2%. Short-chain fatty acid production increased (P < 0.01) compared with control only at 24% and 48% HP 300. Conversely, branched-chain fatty acids were reduced (P < 0.01) compared with control at inclusion rates of HP 300 of 8 – 48%. Overall, these data suggest that HP 300 is a suitable replacement for PBM in canine diets up to at least a 24% inclusion rate.