Onion
Source: https://cdn-prod.medicalnewstoday.com
Whether eaten cooked, raw, or in powder form, large quantities of onion can oxidize the red blood cells of dogs, and when these cells deteriorate, anemia may result. Another of the Allium plants, people need to be wary as onions are commonly used in cooking and even if it’s only consumed in small quantities, doing so regularly can cause poisoning, with symptoms like vomiting, weakness, and loss of appetite.