Inbreeding brings out recessive traits. Closely related dogs are more likely to have the same recessive problems. I have heard of deliberately breeding siblings to see if there are problems. If that doesn't produce problems, then likely there won't be problems breeding to other dogs. So the answer is maybe, maybe not. A cross breeding is less likely to produce problems than 2 dogs of the same breed.

I am trying to sort this out. Am I correct that your Akita is a male and was allowed to breed with a female from a litter he sired with the Belgian Shepherd? Accidents do happen, and there are legitimate reasons to breed crosses. However this sounds to me like some of the irresponsibly that leads to millions of dogs being slaughtered in the shelters for lack of good homes. You are keeping one puppy from this last litter, but will all the rest have good homes? I really hate to criticize responsible people who are not part of the problem, but if you had done even a start on the research you need to do before being able to make good decisions, you would not have posed this question here. The AKC has a great discussion about responsible breeding on their web site at www.akc.org. Please go there and read it.

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Something funny has happened here. I posted the above in response to a question where a dog bred its daughter. The question is gone leaving my answer as a question.

Saying why a dog does something can be difficult, let alone explaining a web site.