Eli Lilly (LLY -0.89%) is one of the most prominent drugmakers on the globe. However, with a market cap exceeding $62 billion and product offerings in a wide range of therapeutic areas, it can be difficult for investors to understand every aspect of its business. In this segment, health care analyst Max Macaluso takes a close look at a specific division that generated more than $2 billion in revenue last year but that many Lilly investors might not know about: animal health.