Unfortunately not all Rhodesian ridgebacks have their unique element - a ridge on their back. This depends on the combination of parents' genes. Ridge is visible when puppy is born. And yes, it happens not so rarely. That is why breeders do genetic tests and according to test results they select best combination of parents. 

Ridgeless dog is considered as pet dog. Owners of a ridgeless Rhodesian Ridgeback can not participate in dog shows. 

But don't worry - even without the ridge Rhodesian ridgeback will have same character as his siblings with the ridge!

The peculiarity of the breed is the ridge on the back, which is formed by the hair growing in the opposite direction to the rest of the coat. The ridge is the escutcheon of the breed. The ridge must be clearly defined, symmetrical and tapering towards the haunch. It must start immediately behind the shoulders and continue to the hip (haunches) bones. The ridge must contain only two crowns, identical and opposite each other. The lower edges of the crowns must not extend further down the ridge than one-third of its length. A good average width of the ridge is 5cm (2”).

FEDERATION CYNOLOGIQUE INTERNATIONALE FCI

Standard N° 146