First, read the English article below.

Your dog's vulva is located directly below her anus. Before your dog goes into heat, her vulva will start to swell slightly. When she is in full heat, her vulva will swell to three times its normal size and will take on a reddish color. Vaginal bleeding is a sign that your dog will soon be going into heat. When your dog goes into heat, the amount of blood will decrease quite a bit and the blood will become brownish in color.  If a dog is scrupulously clean and licks away the discharge, it can be tricky to know if a discharge is present or not. A useful tip is to cover her bed with a white sheet or pillowcase. That way when she is asleep you will see blood spots on the white cover. If you plan on breeding your dog, write down the day that the bleeding begins. Breeding is best done on the 10th or 11th day after the first day of bleeding and then every other day after that for three days. Another sign that your dog is entering heat, or in its early stages, is if she constantly licks her vagina. While some female dogs won't do this, most dogs will develop this behavior right around the time that they go into heat. Dogs who are in the early stages of heat tend to develop behaviors that they do not typically display. In particular, female dogs who are about to go into heat are usually nervous, agitated, or easily irritated. Some dogs will also bark more or become more aggressive with people and dogs around them. If your female dog begins mounting male dogs or other dogs, she is more than likely in heat. Mounting is a common sign that a dog is in the full swing of heat. She may even try to mount your legs. However, dogs can mount legs or each other for behavioral reasons, such as masturbating, dominance, or bizarrely from submissive behavior, so this does not automatically mean a dog in heat. When a female dog enters heat, she will curl her tail to one side, making it easier for mating to occur. This action is called 'flagging' and is a common behavior of dog in heat.  You may also elicit this behavior by giving her... 

Now, please write a short abstract for it in Vietnamese. Abstract:
Quan sát nếu âm hộ của chó bị sưng. Lưu ý những dấu hiệu chảy máu âm hộ. Lưu ý xem liệu chú chó có liên tục tự liếm mình hay không. Lưu ý nếu chó của bạn bắt đầu cư xử bất thường. Lưu ý về sự gia tăng các hành vi ghép đôi. Quan sát sự thay đổi về vị trí đuôi của chó.