The Bernese seem to commonly have soft poops and digestive issues so I have found that adding a probiotic to their diet to be extremely helpful. Here we currently use Bayer Animal Health Lactoquil Soft Chews that we purchase from the vet but I have also heard great things about the product Bernie’s Perfect Poop, i just personally have not tried it out myself yet for my own personal dogs. Adding a probiotic to their diet seems to help with firming up their poops.
Some Website Links to purchase the products:
https://www.perfectpoop.dog/products/bernies-perfect-poop?variant=31051661836322
Bayer Animal Health Lactoquil Soft Chews, Daily Digestive Probiotic Supplement, contains naturally derived ingredients for dogs of all ages, sizes and breeds, 75ct (86582961) https://www.amazon.com/dp/B00A4JGL1E/ref=cm_sw_r_cp_api_i_0P50GK6AXHBV46W2J6TF