If a cat gets lost in the winter, you may have the opportunity to track him/her without the use of a search dog. This method would be most useful for escaped indoor-only cats since they are frequently hiding close to home. However, it may also be useful for finding an outdoor-access cat if there are not many other cats in the area where s/he went missing.
Domestic cat tracks are oval and are an average of 1 1/4 inches in diameter (specific measurements from Elbroch 2003: front track L: 1 – 1 5/8 in. W 7/8 – 1 3/4 in.; rear track L 1 1/8 – 1 1/2 in. W 7/8 – 1 5/8 in.). The front track often appears asymmetrical, and the claws usually do not show in either track. The walking stride is 6 – 12 1/2 inches long and 2 – 4 3/4 inches wide. In deep, powdery snow, the prints may not be visible, but the trail shows a distinct triangular pattern.
Recommended Tracking Books
Elbroch Mark. 2003. Mammal Tracks and Sign: A Guide to North American Species. Mechanicsburg, PA: Stackpole Books. (This is my favorite field guide but with almost 800 pages of glossy photos, it is a little heavy for taking into the field.)
Halfpenny, James C. and Jim Bruchac. 2001. Scats and Tracks of the Northeast. Guilford, CT: Morris Book Publishing, LLC. (There are similar versions of this handy little field guide for different regions of the US.)
If you want to learn more about the skill and art of tracking, I would recommend the following books:
Rezendes, Paul. 1999. Tracking and the Art of Seeing: How to Read Animal Tracks and Sign. New York, NY: HarperCollins Publishers.