How can I keep my dogs away from my tomato plants that have the cages

Oh dear! Well at least they ate their veggies and are healthy!

Is it possible to put up some sort of small fence around them for a visual barrier?

I have 3 dogs and the neighbor has 3 dogs, plus 6 cats. After each addition, it took a lot of training and temporary fencing to keep them out of the veggies and herbs, but it can be done.

You will have to put a fence around them.

try loose fitting netting-- over the tomatoes should be light weight enough to not damage but discourage any intruders. Birds like them too!

When catch them near the plant go to the dog point away from the dog and say OUT. MUST BE CONSISTENT with yourself and the dog

Restrict where the Dogs can roam or rais your tomato plants up off the ground to a point where the dogs can't get them. Grow them in Hanging Baskets.

Put a small fence around them.

Either fence them in, or put them in a raised bed garden that is enclosed.

I've used hanging planters and it works well, no one can reach them so high up.

Motion activated sprinkler.