The HRS has a list of safe veggies you can feed so it’s a good idea to check it out: https://rabbit.org/suggested-vegetables-and-fruits-for-a-rabbit-diet/

Romaine is alright and lots of people feed it to their buns. There seems to be cases of contaminated romaine in the U.S. (I think?) right now though, so depending on where you are, you may want to stop getting that for now.

There are disputes on whether kale should be given often as some bunnies have gotten bladder sludge from it. Spinach is also high in oxalic acid and should not be given very regularly. Cabbage and carrots should also not be given daily. Cilantro and rocket lettuce can actually be given more regularly.

There is indeed an E-Coli outbreak connected to romaine lettuce in the USA at the moment, I don’t know how/if it affects rabbits, but it might be safer to avoid that if you live there. I think all kinds of lettuce apart from iceberg and possibly butter are ok, right? I give mine a bit of parsley and bok choy too.

Your vet would be right in saying that. Lettuce doesn’t actually contain that much nutrients a(think about it-hlw
many people have told you to eat your lettuce to be healthy? ) It’s mostly water. Additionally iceberg lettuce is actually unhealthy, containing components that are actually poisonous.
Bunnies need 5 types of different veggies a day in order to be truly healthy. However, that’s what pellets are for-they contain all the vital nutrients your bunny will need, so leaves mainly contribute to healthy teeth and mental stimulation.

As for the current romaine lettuce issue in the U.S. (which is the second time this has happened in the past half-year or so; seriously, people in the agriculture industry are getting sloppy), this affects romaine harvested in the Yuma, Arizona region. This is why the Centers for Disease Control is advising people to not eat romaine unless they know it’s not sourced from that area. I avoided romaine last week due to this, but stores and restaurants have gotten it sorted out so I was able to get Panda and Fernando a nice head of romaine this past weekend from a supermarket that’s sourcing its romaine from areas other than the affected one.

To follow up, I’ve read that the lettuce-growing season for the affected area (Yuma, Arizona) is now over, so there won’t be any more lettuce coming from that region until the next harvest, so I’m expecting the warning to be lifted fairly soon if there aren’t any more incidents of illnesses.

Romaine lettuce is fine, however it’s the sort of thing where you don’t want all or half of their salad to be romaine. I just use 1-2 leaves for my pair each day along with an assortment of other greens and herbs so the romaine ends up only being 10-20% of their salad. Less of more variety is better than more of less variety