1 Retained by their creators or by archive service providers, such as national or local government archives, university archives, or other archives that collect and maintain archives of other organisations. 2  A great national resource as they document the history and identity of communities throughout the country.
Although six months old is the average age of a dogâs first heat, this can vary widely. Some dogs can go into heat as young as four months, while larger breeds may be as old as two years before their first heat. Responsible breeders never breed a dog on her first or even her second heat. It is considered best practice to wait until her third heat, at about 18-24 months.
Surprise! Although there are always variations, cats can have their first heat as early as 4 months old, and dogs can have their first heat as early as 5 to 6 months old; and if they can come into heat, they can get pregnant! With 50% of litters being accidents, you can see how unwanted litters can add up quickly.urprise! Although there are always variations, cats can have their first heat as early as 4 months old, and dogs can have their first heat as early as 5 to 6 months old; and if they can come into heat, they can get pregnant! With 50% of litters being accidents, you can see how unwanted litters can add up quickly.