Aminopterin, PETA, Anna Nicole Smith and conspiracy theories

Pet owners across Canada and the United States are worried that they've been feeding their dogs and cats poisoned food. Today, that poison, aminopterin, has been blamed for over a dozen animal deaths, and more are likely to be blamed on the contamination. The company that made the food, Ontario-based Menu Foods, is trying to understand how the poison, which is not licensed for use in North America, got into the supply chain. While we wait, I'm going to indulge in some irresponsible musing about who would stand to gain from this.