Dogs that are suffering from an overdose of acetaminophen simply will feel very sick. They will become progressively and increasingly depressed and suffer abdominal cramping and pain. This often will be accompanied by retching and vomiting. Unfortunately, these symptoms are relatively nonspecific and can be attributed to any number of things other than acetaminophen toxicity. However, from the dog’s perspective, the results of ingesting too much acetaminophen will cause it to feel lousy, sick, sore, nauseous, lethargic, depressed, weak and wobbly. The signs usually become quite evident to the dog’s owner within a few hours of its ingestion of acetaminophen.