What happened on the A329m today?

[onyx39]

Probably nothing major, but a bit odd. Driving home about 4pm, suddenly hit the back of a jam. Didn't move for a good 20 minutes, people out of the cars etc walking around.
During that time 2 bib astra's and a Highways agency pass me.
Suddenly traffic heads off, soon up to speed limit.
After a quarter of a mile, I see a Merc estate on the opposite carriage way, no visible damage, a Police Astra immediately behind it and another 50 metres behind, both with blues on.
I thought it was initially a breakdown, but then wondered if it was a "stop"', if so, is it likely that my carriageway would have been closed?

[MantaMike]

Heard on the local radio traffic news that there was a dog loose on the carriageway, held the traffic to round it up!

[Xtremescoobys]

Who let the dogs out! Must of been a Rover

[SVTRick]

This thread will go Barking Mad now....