Why must dogs stop, sniff and pee every 5 yards?

Tuesday, December 25--
Merry Christmas. Report: easy 2.2M loop with Bosley the dog and another easy 2.2M (17:05) solo. Why must dogs stop, sniff and pee every 5 yards?
Looking forward to a good race(s) tomorrow at the Armory.

The 400 (goal)

1st 150--19.7 sec
2nd 150--20.3 sec
last 100--14.5 sec =54.5

OR

1st 200--26.5 sec
2nd 200--28 sec = 54.5


Possible reality...

1st 150--20.2 sec
2nd 150--20.6 sec
last 100--14.6 sec =55.4

OR

1st 200--26.7 sec
2nd 200--28.7 sec = 55.4