If you plan to breed your female dog, you must know the best time to breed her. Most females go into heat for the first time between 8 and 11 months of age. If you do not want to breed your dog, knowing when she will be in heat is critical to keeping her from getting pregnant. Females go into heat twice a year, or every six months. If your dog has been spayed, she will not go into heat and cannot be bred.
Mark on your calendar the first day you see your dog is in heat, or bleeding from the genital area. Count six months to the day to determine the next time she will go into heat, and mark this date on your calendar as well so you can prepare ahead of time. Heat lasts three weeks, and breeding is best done on the second week, when fertility is at its peak.
Purchase disposable diapers and diaper garment that will fit your breed. Generally, there are seven sizes ranging from extra small to extra large. The extra small is used for breeds with weights up to 4 lbs., and the extra large is used for Great Danes, rottweilers and Saint Bernards with weights topping out at 120 lbs.
Keep your dog inside if you do not intend to breed her during the three weeks of her time in heat. Male dogs in your neighborhood will be in your yard and will jump fences and incur bodily harm to get to a female in heat.
Pull the diaper out of the package, and unfold it completely. Keep your dog calm while pulling the tail through the tail hole in the rear of the diaper. Most females are protective of their genitals during heat, so you may encounter resistance.
Pull the top of the diaper over the back of your dog, and reach through the legs to get the lower section of the diaper to fasten. Pull the tabs open, and pull snugly against your dog's back to fasten.
Pull the diaper garment over the diaper in the same manner. The Velcro straps attach the same way as the diaper, and will hold the diaper in place so your dog does not shed the diaper out of aggravation.
Check the diaper every few hours during the first week. If your dog has been bred before, she will have a heavier flow and will require changing more often.
If you have male dogs in the household during the heat period, use a safety gate to separate the animals or place your male dog outside or in a dog crate to keep him from trying to mate.