According to this ASPCA List Akebia quinata is not toxic to dogs. This ARTICLE has more info that the plant is non-toxic.

The plant is invasive; its seeds are spread by birds. And, it will re-sprout from the roots. Feel free to remove them completely, but that means digging out as much of the base as possible, then possibly using an herbicide on any sprouts. As these are spread by seed keep an eye out for new plants on your property. Here is info on Managing Akebia.

I wonder if the word ’chocolate’ was a warning sign to a dog owner?

There is a large, well established Akebia growing up a support in an open sided greenhouse structure at my local nursery. It was already growing there when I first started working there 15 years ago. It gets trimmed back when it gets too wild and woolly but otherwise is left to its own devices. Smells heavenly when in bloom but to my knowledge, has never produced fruit. Can't imagine a dog being the slightest bit interested in the fruit anyway as it is unappealingly gelatinous.

Granted, growing up a wooden greenhouse support is not the same as growing on a house pillar but even in the humid, warm atmosphere of the open green or lath house, the vine has caused no damage.

I also would not be overly concerned about invasiveness. Eastern WA state is a very different climate and environment from where the plant has been reported invasive and virtually no plants that are considered invasive species in the eastern half of the country have similar issues here in the PNW. Invasiveness is always heavily influenced by regionality and climate......location, location, location :-)

If they were growing on my house, I'd leave them.

IMO without pictures how do we know what this even looks like. As for the vine itself I think any invasive plant needs regualr control and IMO this situation is a disaster waiting to happen since the vive is so invasive and I can't imgaine it on support posts all across the front of a house so I need pics.Photo

It is NOT invasive in Washington state. Or anywhere west of the Rockies. And vines are grown on or against houses all the time with NO adverse impact. In the eastern half of the state, it should be fully deciduous anyway.

If the OP doesn't like it, then have it removed but its location is not a major concern.

Chocolate vine tends to twine rather than attach when in the air, so it won't dig into your posts like some other vines can. Since it sounds like you have more than one plant, you might get fruits on some of the vines. It's not common the further north one is, but it can happen. If your support posts are spaced apart, it's less likely to happen- they like to be close for pollenation. If they aren't in good full sun all day, that can decrease chances of fruiting as well.

If you are uncomfortable with them growing up the supports, you sure can cut them back and install trellis if you like. Best time to hard prune them is after it's spring flowering and when its starting to die back a bit as we get into summer. You can cut them down pretty hard, and by some recommendations it should be pruned hard every few years to cull out the old wood and encourage new green growth. Otherwise, you can trim off leads and wandering vines every couple months if they get unkempt.

If you want to remove them entirely. Cut them to the ground now since it's about the right time for hard pruning anyway. Then you need to dig them out- be sure to get all the roots because they will resprout. As an alternative, you can try covering them to help smother and continue to cut back any green growth till it gives up, then dig out the root mass best you can. Or you can use an herbicide after you cut it down to help kill it. before you dig out it's root mass.

Do not let the vines sit on the ground- they will want to start attaching through stem nodes. Be sure you hang up to die or bag up as you cut the stuff down. Do not add to the compost pile, even if they seem full dead.

If you like them and want to keep them. If they aren't really producing flowers, amend them with a higher phosphorus fertilizer or blood meal.