Hi Charlotte, I’m also in the UK …we answer questions on here from a lot of countries.
This episode with Walter needs Veterinary attention. We cannot diagnose on here but this could be anything from a seizure to a mini stroke to something lacking in his blood/diet…..and needs professional assessment to find out what is going on.
I hope Walter is ok and try to keep him calm and quiet until you can get him to a Vet later today hopefully. Good luck.
I had a dog for 15 years, she Loved to chew apart a log or stick and this same sound of coughing would happen but only for a few hours, so I know thi IS a common problem. Thanks anyway.