Why those two slices won't trouble a beagle
A 12 kg dog can handle small amounts of plain cooked vegetables without issue. The two slices your beagle grabbed are roughly the size of a couple of cucumber rounds — not enough to cause anything beyond mild curiosity in her digestive system. Since the lotus root was cooked, it's already broken down enough to pass easily.
Dogs this size often snatch much richer foods without consequence, so plain lotus root is one of the safer things she could have taken. The only concern would be if it was seasoned with something like onion powder, but you'd likely have noticed that by now. Just let her drink normally and observe her stool tomorrow.
How her weight changes the calculation
At 12 kg, your beagle has plenty of body mass to process tiny vegetable portions. Smaller dogs might react to unfamiliar fibers, but her system can handle this without straining. Compare it to a human eating a single carrot stick — noticeable, but not impactful.
Her stomach acid will break down the slices within an hour or two. You might hear some gurgling as her gut adjusts to the new fiber, but that's just normal movement. If she were under 5 kg, we'd be more cautious about even small amounts of new foods.
What 'plain cooked' means for safety
Raw lotus root has tough fibers that could irritate a dog's throat, but cooking softens it completely. Since these were boiled or steamed slices without oils or sauces, they're essentially just starchy water-filled cells now — harmless at this quantity.
The cooking process also eliminates any residual soil bacteria that might cling to raw tubers. What's left is comparable to a bland potato slice, which most dogs tolerate unless they have known grain sensitivities. No need to check her gums or temperature over this.
When to relax versus when to react
Over the next 6 hours, you might see her drink slightly more water as her body processes the extra fiber. That's normal and actually helpful. Only consider calling your vet if she produces watery diarrhea multiple times or strains without passing anything.
Given the time that's passed since ingestion, any adverse reaction would have started by now. Since she's acting normally, you can assume those slices are already moving through her system uneventfully. Next time, maybe keep the lotus root farther from the table edge!
The full verdict, portion guidance and serving notes are collected on the Lotus root food facts page.