Why the 10 kg dog is the only one at risk
A whole cooked sweet potato is a significant volume for a medium-sized dog, even though the ingredients aren't toxic. The dog who ate it may feel uncomfortably full or gassy, while the dog who didn't eat any has no exposure to monitor. Their digestive systems work independently—what one ate doesn't affect the other unless they're sharing symptoms like contagious illness, which isn't the case here.
Focus your attention on the dog who consumed the sweet potato. Check their abdomen for unusual firmness or distension, and note if they're reluctant to lie down or seem restless. These signs would suggest their stomach is struggling with the sheer quantity, not poisoning. The other dog requires no special observation beyond their usual care.
What a bloated belly looks like in this case
A 10 kg dog with too much sweet potato may show subtle swelling along the ribs or a tighter-than-normal waist when viewed from above. Gently press the sides of their belly—it should feel like a half-filled water balloon, not a drum. True bloat (GDV) is rare from food alone, but any rapid swelling, unproductive retching, or pale gums means an immediate vet visit.
More likely, you'll see milder discomfort: pacing, lip-licking, or turning down treats. These are signs to withhold food (including the other dog's meal if they try to steal it) for 4–6 hours, then offer a quarter of their normal dinner. Hydration is safe—keep water available unless they're gulping it excessively, which could trigger vomiting.
When vomiting becomes a concern
One or two vomits of undigested sweet potato chunks in the first few hours are the stomach's way of reducing the load. It's only worrisome if the vomiting persists beyond 3 episodes, contains bile (yellow foam), or happens after 8 hours when the food should be moving to the intestines. At that stage, dehydration risk rises, especially in smaller dogs.
Prevent overdrinking by offering ice cubes or small licks of water every 15 minutes if they've vomited. The other dog can drink normally. Neither needs anti-nausea medication unless prescribed, but do call a vet if the vomiting dog seems weak or can't keep water down after 2 hours. The unaffected dog needs no intervention.
Why their next meal matters
Resist the urge to 'balance' things by giving extra food to the dog who missed out. Their systems aren't keeping score, and overfeeding the second dog could cause its own digestive upset. Stick to their scheduled portions—if the sweet potato eater skips a meal due to fullness, that's okay. Missing one dinner is safer than forcing food into an already-stretched stomach.
For future meals, consider dividing treats like sweet potato into pencil-sized pieces for a dog this size. What seems like a small side dish to us is a mountain to them. The other dog isn't missing nutrients; commercial diets are complete, and occasional skipped snacks are harmless. Watch the potato-eater's poop for undigested orange bits over the next day—this confirms their system is processing it, however slowly.
The full verdict, portion guidance and serving notes are collected on the Sweet potato (cooked) food facts page.