Begonia can cause oral irritation, intense burning and irritation of mouth, tongue and lips, excessive drooling
, vomiting, and difficulty swallowing but it's the tubers that are the most toxic
. Insoluble calcium oxalate crystals are responsible. Washing out your dog's mouth with copious amounts of water is indicated. Senecio species such as the silver dust are more dangerous. They contain pyrrolizidine alkaloids. Clinical Signs: The plant is not very palatable to dogs and is usually eaten by ruminants with no other forage; poisonings typically occur from ingestion of green plant material or material in hay. The toxic components can cause liver failure, referred to as "walking
disease" or "sleepy staggers". Signs include weight loss, weakness, sleepiness, yawning, incoordination, yellowish discoloration to mucous membranes (icterus), neurologic problems secondary to liver failure (aimless walking, chewing motions, head pressing). Animals may appear to be normal at first, then become suddenly affected; the syndrome progresses rapidly over a few days to a week. Liver damage, depression, anorexia, vomiting, diarrhea, muddy mucous membranes, weakness, ataxia
can also be seen.It would be prudent to induce emesis by dosing your dog with 3% hydrogen peroxide at a dose of 5 mL (one measuring teaspoon) per 5 lbs of body weight (maximum dose of 45 mL - 3 measuring tablespoons) by means of a small poultry baster placed between its cheek teeth and cheek. Your dog should vomit within 15 minutes. If not, repeat the same dose.