The row of collies in Young Ones although I don't think they were real dogs.
The Young Ones episode Interesting also has four horsemen of the Apocalypse and I can remember thinking when I first saw it how calm the horses were. They are probably among the most expensive animals to hire because the transport is difficult and they also have to be trained to be comfortable around a lot of action. I bet back then the horses were as expensive to hire as the actors or probably more if the guys were on Equity minumum https://www.youtube.com/watch?v=_EO6abKG5Hg
I wonder if the BBC, as a public service have to put out a tender when they need animals for filming so they can be seen to be choosing the best value services. I would love to see some of those and they are probably available under the freedom of information act
1 x otter
3 x fillies
1 x moose
1 x hedgehog
assorted cats and dogs (10)
I know of the amazing work the Humaine Society does but is it a legal requirement for them to be on set in any UK television production when animals are used?