Changes

During World War II, when metal was rationed in the US (and pet food was classified as "non-essential"), canned pet food wasn't available and the production shifted to dry foods. By 1946, dry food represented around 90% of the US pet food market. This led to the next big innovation in the 1950s, by Ralston Purina, with the use of the extrusion process for cat and dog food manufacturing. For the first time ingredients were combined, cooked and pushed through a mechanical extruder, which expanded the food. This made a larger, lighter and more convenient food much the same as we know today.

During World War II, when metal was rationed in the US (and pet food was classified as "non-essential"), canned pet food wasn't available and the production shifted to dry foods. By 1946, dry food represented around 90% of the US pet food market. This led to the next big innovation in the 1950s, by Ralston Purina, with the use of the [[Dry Pet Food Manufacturing#Cooking and Cooling|extrusion process]] for cat and dog food manufacturing. For the first time ingredients were combined, cooked and pushed through a mechanical extruder, which expanded the food. This made a larger, lighter and more convenient food much the same as we know today.