The first part of heat you will notice bleeding from the vulva, swelling of the vulva, possible increase in urination and the most noticeable, male dogs hanging around the house. (vetinfo.com)
As signs progress, dogs become increasingly lethargic and dehydrated, refuse to eat and may show a transient increase in urination followed by decreased or absent urination in later stages. (peacerivervets.com)
Since one of the functions of the sympathetic nervous system is an increase in urination, heightening the action of the SNS can lead to excessive urination. (mypetneedsthat.com)