Onions contain a compound which is toxic to the red blood cells of cats. The red blood cells are destroyed and this results in anemia. The specific type of anemia is called 'Heinz body anemia' because the red cells develop an abnormality called a 'Heinz body' which can be seen under the microscope.
Dug, the dog, is easily distracted by ... squirrels (well, he's easily distracted by everything, but especially squirrels). He can be talking (yeah, it's Pixar/Disney so the dog talks) & right in the middle of the sentence, he shouts, Squirrel!. Then he carries on with whatever he's talking about.
Snoopy often lies on top of his doghouse and sleeps, sometimes all day long. In one strip, Charlie Brown refers to him as a hunting dog, because he always hunts for the easy way out of life. In later strips, Snoopy's main human contact (when not indulging in his fantasy life) is with Rerun van Pelt.