IMO it is a myth that Basenjis cannot have good manners on a walk. Yes, great if you can do off leash, but when circumstances dictate that a leash is necessary then walking calmly without a lot of drama and pulling should be achievable. Personally I do not like long lines or flex leashes. Or allowing dogs to eat whatever they find on the ground, which can in some cases earn you a trip to the vet or worse. Like most dogs, Basenjis are not overly discriminant about what they will ingest. A short leash and being observant can protect them from unwelcome outcomes. Mental exercise will also go a long way with any dog. But one should have a definite opinion about who is running the show, and it should not be the dog....they are quite willing to take up the position should you abdicate.
