Onions cause hemolytic anemia in dogs (and cats). Allyl propyl disulfide has been reported as being considered to be the main cause of onion poisoning in dogs. Thiosulfate has also been implicated. Thiosulfate levels are not affected by cooking or processing. Occasional exposure to small amounts is usually not a problem, but continuous exposure to even small amounts can be a serious threat. Also garlic contains thiosulfate, even if to a significantly lesser extent, and it is also known to cause diarrhea and vomiting. Other signs of toxicosis include pale gums and intravascular hemolysis.