Trees, Shrubs and Conifers: trimming pine trees question, 1 by DevilDogs

DevilDogs wrote:
I have a stand of pine trees in my pasture that my horses use for shelter from the sun, wind and rain. They prefer their "fort" to the run in most of the time.
Against my wishes, the entire inside and "entrance/exit" was butchered. All the branches going about 4 or 5 feet up were cut off and many were just cut down. I'm concerned this will weaken the trees, open them up to the possibility of disease and/or bug infestation, or just plain old kill them.
Is this a valid concern, and if so, is there anything I can do at this point to save them? I'm not sure what kind of pines they are but have attached a picture of the center area where they hang out.
Thanks,
Kristen