Female Dogs Menstruation Period

Small dog (small-sized), like a chihuahua and poodle, had loop (menstruation) at age 5-6 months. Race with a medium size, such as husky and harrier, experiencing his first loop at the age of 7-8 months. While the big race, like the great dane and rottweiler, having first loop at the age of 9-10 months.
The loop time female dog usually reaches nine days. Well, while to determine the fertile female dogs, there's an unique way.

Every dog breeders, dog vagina must check every day. By rubbing a tissue, on the genitals, if there was blood or mucus. Female dog will be ready to be mated, if it has undergone a second loop.

In the meantime, to find out whether the fertilization process got them pregnant, could be seen from the shape of the female's vagina. If a week after mating vagina is open, the dog has been pregnant.