Stop listening if you can't reach a backend

I'm working on a weird app which just stops listening ("connection refused") in some conditions, and the just as weird client relies on this. I'm using haproxy to load-balance to several application servers. Is there a simple way to have haproxy stop listening when it detects no backend is responding during its checks? If not what would you advise we use to trigger a script to do that based on the log contents?  

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