Grey Iron began as the Grey Iron Casting Company in 1881. It began producing toy soldiers in 1914 and was most active up until World War II. In 1967 the company was merged into the John Wright company that still produces iron products. Toy soldiers and animal figures do not seem to be in production at this time. The company produced two very different groups of animals.
Animals in this line were flats similar to Zinnfiguren. They were painted white and boxed with paints for the child to color themselves. It's unknown if there were other animals besides those listed here.
American Family Series
Grey Iron produced groups of figures along a family civilian theme. These included The American Family Travels and The American Family on the Beach sets that had no animals. There were three series that did include animals.