Danny Colyer wrote:

I remember sometime in the last few months seeing an advert in a
magazine for a modular trailer (single base, multiple possible tops).
One of the modules was designed for towing dogs. Can anyone tell me off
the top of their head what make the trailer might have been, or whether
it has a website?

Not sure of the name or URL, but it was sold in the Bike-Gear catalogue
that came with Cycling+ a few issues ago, if that helps.