Why 2 hours without symptoms means clear sailing
For a 10 kg dog, the gastric transit time of a small tofu piece is approximately 90 minutes—meaning it's already moving into the small intestine by now without triggering stomach upset. This is the critical window where vomiting would have occurred if the soy disagreed with your dog's system. The absence of retching or drooling strongly suggests their body accepted the tofu as just another protein source, no different than their regular kibble.
Intestinal reactions work on a slower timeline but still within predictable bounds. If the tofu were going to cause loose stools, signs would emerge between the 4-6 hour mark as it reaches the colon. Your dog's normal behavior at the 2-hour checkpoint means any later issues would be exceptionally mild—perhaps slightly softer stool at most, not the urgent diarrhea seen with genuine food poisoning.
The weight threshold that makes this bite insignificant
At 10 kg, your dog's digestive capacity is robust enough to handle this quantity without breaking stride. Veterinary toxicology calculations for problem foods always factor in grams per kilogram of body weight—here, the ratio is so minimal that it falls below clinical relevance. This wasn't enough tofu to displace nutritionally significant amounts of their normal diet or alter gut pH meaningfully.
Compare it to their daily food volume: if your dog eats roughly 200 grams of food per day, this tofu scrap represents less than 1% of that total. Their pancreas secretes sufficient enzymes to process such trivial additions without strain. Even dogs with sensitive stomachs (which yours clearly isn't, based on the 2-hour report) typically tolerate these trace amounts unless they have a diagnosed soy allergy—which would have manifested long before now through commercial foods.
How meal timing affects symptom development
Whether your dog ate the tofu on an empty stomach or between meals changes the expected reaction pattern slightly. Empty-stomach consumption often speeds transit time, potentially leading to quicker (but still mild) symptoms if any occur. Given that you're already past the peak reaction window with no issues, the tofu has likely been incorporated into their digestive process without fanfare.
The next scheduled meal will confirm normalcy. Dogs that experience even minor stomach upset often hesitate before their next bite of food—a protective instinct. If yours eats dinner with their usual enthusiasm, you can definitively rule out gastrointestinal irritation from the tofu. Should they pick at food but still drink water normally, monitor one more sleep cycle before considering a vet check.
Why breed traits matter more than the tofu itself
Larger dogs like yours metabolize plant proteins more efficiently than toy breeds, with more intestinal surface area to absorb nutrients. This explains why the same quantity that might give a Yorkie soft stool passes unnoticed in your 10 kg dog. Their colon has greater capacity to reabsorb water from digesting matter, preventing the loose stools that sometimes follow unusual foods in smaller systems.
Activity level provides another safety buffer. More muscular dogs generate faster gut motility through movement, preventing food stagnation that could theoretically cause fermentation. Unless your dog has been unusually sedentary since eating the tofu—which you'd have mentioned—their normal walking and playing has already assisted optimal digestion. The 2-hour mark with no symptoms plus their healthy weight makes this case medically unremarkable.
The full verdict, portion guidance and serving notes are collected on the Tofu food facts page.