Deer maybe? Dogs ? The good news is that they will survive and put out new foliage (given a chance).

A broken branch or two doesn't make for "destruction". The rest of the plant will survive and, as noted, stems will replace the ones that broke off.

Dan, here in the PNW, our growing season for tomatoes is very short ( especially this year with unusually cold temperatures). Any setback can mean no fruiting. I see you are in Texas. I envy your heat right now!

any more ideas on what shreded these stems?

It might be that a bird or animal landed on the plant and was too heavy; or I'd go with perhaps a squirrel. I've had squirrels do similar damage when they need water... but then I'm in central California where summers are dry and water is a precious commodity.

Squirrels will chew through branches to fell them and get at the fruit. Could also be something big and clumsy like a groundhog? But if the damage isn't at ground-level, my money's on squirrel.

Deer make very clean cuts when they sample, so doubt they are the issue......my 'maters get pruned regularly by deer if I am not diligent with the spray :-) My guess is either squirrels or rabbits, so I'd try some hot pepper spray to discourage them.

And I'd not be overly concerned about the damage. As long as you have selected varieties best for this area, there is plenty of time for them to produce new stems and flower and fruit. We haven't even come close to our 'hot season' yet, such as it is :-)

I wouldn't worry about the damage, but I'd do something ASAP to dissuade them from doing further damage.

Sometimes, though, just to warn you, there's an overpopulation of squirrels due to environmental factors, and if you have a population of desperately hungry squirrels, nothing except locking the tomatoes away behind a wire cage type barrier they can't penetrate will work, and your plants will be completely destroyed.

Under normal pressures, deterrents based on scent or hot pepper type deterrents may work.