Im not sure if technically they can, but practically they can as that what we used to transport our dexters - we had to make two trips though as 3 cows, 1 steer and 1 calf wouldnt all fit in at once.
We also used a sheep hurdle over the top of the back door rather than fully closing it up - Im not sure if we needed to do that or not but we felt better with them having some light coming in.
Regards
Mark