Why does my dog urinate in her sleep?

As female dogs age, especially ones that have been spayed, they start to lose control over the bladder muscles. This is called urinary incontinence. Generally, the first sign that a dog is becoming incontinent is urinating or "dribbling" in her sleep. Your vet should be able to prescribe a supplement that can help with bladder strength. If your dog is still young, there could be an anatomical issue that may need to be addressed. In either case, a visit to the vet is going to be the best route to go.