Dogs sniff urine for different lengths of time
The information available in canine urine is astounding. From a proper sniff, dogs can learn about the sex, reproductive status, diet and stress level of dogs who have been there before. Urine is used to communicate about territories, to mask the smell of other dogs, to detect females who are likely to be reproductively receptive and to compete with other individuals. It’s no wonder that our canine friends find urine so compelling that they are irresistibly drawn to it. As anyone who has spent even a little time with dogs knows, urine sniffing is a favorite pastime.
via Whisker Therapy