Dealing with a dog's discharge while she's in season isn't pleasant, especially since you must take great care about letting her outside. Even if your backyard has a high fence and seems escape-proof, a dog in heat can develop Houdini-like abilities. It's even more likely that some neighborhood male dog will defy the laws of gravity to get to your girl. Except for brief constitutionals under your close supervision, she'll have to stay -- and bleed -- indoors.
Canine Estrus Cycle
If your female dog isn't spayed, expect her to enter estrus approximately every six months. If she's a small breed, you might have to deal with the bloody, smelly discharge accompanying her heat cycle three times annually. Usually, a canine heat cycle lasts for two to three weeks, although the dog won't bleed that entire time. The initial discharge is fairly heavy, but it tapers off during a seven- to 10-day period. In addition to bleeding, a dog in season also urinates more frequently. She "marks" areas when outdoors -- or possibly indoors -- to let male dogs know she's available.
Your dog probably won't like wearing doggie diapers, but they're your best bet if you want to give her the run of the house while she's in season. While diapering prevents her discharge from leaving stains, you might have to put the dreaded "cone of shame" -- an Elizabethan collar -- on her so she doesn't tear off the nappie. If your dog tolerates diapering, it's probably the easiest way of dealing with her discharge and not limiting her indoor access. You must remove or replace the diaper when she goes outside to do her business. Don't let her outside unaccompanied, figuring a diaper will protect her from impregnation by any stray male dogs. It won't.
Crating Your Dog
If you're away most of the day, crating your dog while she's in season avoids having her discharge all over the house. Crates are relatively easy to clean. Get her used to crating long before her cycle starts. She should see the crate not as punishment but as a secure spot, a safe zone. You can keep her crated while you're home when she's in season, but put the crate in an area where she's able to see you and other family members and doesn't feel left out.
If you have areas in your home with easy-to-clean flooring, that's an alternative to crating your dog. You don't want her having free access to rooms with carpeting or wooden floors, but her discharge shouldn't stain a tiled or linoleum surface, and cleanup is straightforward. If the rooms with the easy-care flooring contain furniture your dog might jump on, cover these pieces with old blankets or towels in case she leaves a mess.