When the pups were born, gender, color, and a description of white markings were recorded with the birth weight. To identify pups without picking them up, I tied colored yarn loosely around their necks. When the pups were six days old, I replaced single strands of yarn with braided yarn. I braided about three to four feet at a time and cut lengths as needed as the puppies grew.

Males were identified with one color of yarn. Females wore yellow plus another color, but were referred to by the other color (that is, the "green female" wore green and yellow yarn).

I photographed each puppy, showing the markings and collar color, to create a permanent record.

Some people asked me if yarn collars posed a hazard to the pups. While I agree there was a theoretical hazard with the pups wearing something around their necks, the litter was raised without a collar incident. The pups that were still with me at 10 weeks of age were separated from each other, which stopped the opportunity for a collar incident to develop between pups.