A. This can be a number of respiratory issues including laryngeal paralysis, laryngeal obstruction, or just a benign condition called reverse sneezing, where it appears he is struggling to breathe but it is actually a tickling of the larynx and completely harmless. See this video for an example of reverse sneezing https://www.youtube.com/watch?v=0IszRBYxsGI
The event has to be seen to give you a better idea of if this is something to worry about or not. I would recommend recording the next episode on your phone and then showing the video to your vet for advise on what to do.
If at any point your pet's tongue turns blue or he passes out or if you feel that he is in respiratory distress, then I encourage you to go to an ER vet.
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