In large doses the most you'll actually see are side effects and interactions with tyramine "in lots of aged cheeses" which will give you a killer headache. Low dosages started early will make it so you'll never need a higher dose and your dog/human will retain their mental capacity right up until other parts of the body decide it's time to go!
Don't just read one article, actually do the research on it. It's one of the safest MAO-B inhibitors out there. Also read up on how monoamine oxidase inhibitors work.