Six months ago I adopted a year-old bitch from a shelter. She'd been in various shelters and foster homes for her whole life. She was already house-trained, leash and crate trained and has a lovely temperament. She learns fast and behaves beautifully around the house and out on walks when she's leashed. However, it's a different story when she's off-leash. She won't come when she's called - at least she'll come but not close enough to let me capture her. She does eventually come when SHE'S ready, but not when I want her to. She's half Basenji and needs to run so I don't want to keep her leashed all the time, but this is a problem. In the past I always had German Shepherds and had no problems with them, but I'm aware that sighthounds are a different story! Any advice please?