Sprouted potato

A plain white potato is not the problem. The problem is what a potato becomes in the back of the pantry. Potatoes are nightshades, and they defend themselves with glycoalkaloids -- solanine and chaconine. Those compounds are not spread evenly through the tuber. They pile up in the sprouts and eyes, in skin that has turned green under light, and in the leaves and stems of the plant. The sprout itself carries the highest concentration in the whole potato, far above the peeled white flesh. Solanine inhibits cholinesterase and disrupts cell membranes directly, which is why a bad potato causes neurological signs and not just a stomachache. Two beliefs get dogs into trouble. The first is that cooking fixes it. Solanine is heat stable: boiling, baking, roasting and frying at home temperatures leave it essentially intact, so a sprouted potato mashed with butter is still a sprouted potato. The second is that trimming is enough. A sprouting potato has already switched into germination metabolism, and the glycoalkaloids have usually spread through the eyes and the layer just under the skin. Cutting out the eyes and peeling deeply is a risk calculation built around a 150 lb adult human, not around a 12 lb terrier. There is no published mg/kg threshold for dogs, so nobody can tell you how many bites are acceptable. Judge by the part and the condition instead. Out: sprouts, eyes, green skin, potato vines and leaves from the garden, and any potato that has gone soft or wrinkled. Seed potatoes are worse still -- they are commonly treated with fungicide and sprout inhibitor and dyed to mark that treatment, so a dog that raids a seed bag gets pesticide on top of solanine. Garden beds and compost piles are the other common exposure, since potato foliage and the small green fruits are toxic too. Signs usually begin 2 to 12 hours after ingestion: heavy drooling, vomiting, diarrhea, and a hunched, painful abdomen. Further along you may see lethargy, weakness, a wobbly gait, dilated pupils, a slow or irregular heartbeat, tremors, and seizures. Neurological signs mean the emergency clinic, now. Call your veterinarian, or the ASPCA Animal Poison Control Center at (888) 426-4435 (a consultation fee applies, and they will issue a case number your vet can use). Have ready: which part was eaten, roughly how much, what time, and whether it was raw or cooked. Do not induce vomiting at home. Decontamination, activated charcoal, IV fluids and cardiac monitoring are veterinary decisions. Store potatoes cool and dark, throw out anything sprouted or green rather than saving it for the dog, and if you want to share potato at all, give a small amount of peeled, fully cooked white flesh with no butter, salt, onion or garlic.