It sounds like what we call a reverse sneeze.
It is caused by having excess tissue in the back of the throat. It gets caught up when in normal activity causing the snorting.
Your dog will be ok while you are gone. Sometimes this snorting can seem like it goes on for a long time, but other than covering his nostrils there isn't much you can do to stop it.
If it is really concerning, you could see a surgical specialist who may be able to remove the excess tissue, but this may not help.
It is good you are concerned.
But he will be ok and live a long life with this bothersome problem.
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Always consult the advice of your veterinarian if you are in doubt.
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