Although much of last year's run of animal health IPOs was largely driven by the expectation of fast-growing demand for products to keep pets and livestock healthy, that trend has been slow to pick up steam--at least according to the latest numbers from the Animal Health Institute. On Jan. 14, the organization announced that spending by Americans on drugs for animals remained flat at $7.5 billion from 2012 to 2013, the most recent year for which figures are available. About 60% of the total went toward medicines for dogs and cats, and sales in each of three product categories tracked--biologics, pharmaceuticals and feed additives--did not change. Release