A: There are various general regulations that affect trailers, notably whether they need brakes.
The maximum weight for a trailer without brakes is 750kg, but there are no regulations that seem to be aimed specifically at the transport of dogs.
I had a purpose-built trailer imported from Germany, specifically made with the welfare of the dog in mind. It has ample-sized compartments, thermal material to avoid extremes of temperature, good ventilation and a long coupling to allow dissipation of exhaust fumes.
These trailers are readily available in the UK and are now a common sight at field trials. While expensive, it is nearly impossible to find one manufactured here with the same excellent features and at a lower cost.
Under the 2006 Animal Welfare Act, you must ensure the welfare of any dog for which you are responsible so, with this in mind, any trailer should be constructed with the dog’s best interests at heart.