Soy is good for most dogs if fed as part of a nutritionally complete and balanced diet. Some dogs will be allergic to soy, but soy allergies are not common in dogs. Some human foods containing soy are not good for dogs, such as soy sauce, which is much too high in salt for dogs.
Most dogs can safely eat soy, with no ill effects. If your dog is allergic to soy, they would show symptoms after eating soy. Symptoms of a food allergy in dogs include itchy skin and/or digestive upset (sickness and diarrhea). If your dog eats soy in a human food, then it’s important to check the other ingredients. Many human foods are too high in salt for dogs, and some are even toxic to dogs. Call your veterinarian for advice if you aren’t sure.
Yes, most dogs can eat cooked soybeans safely. Soybean allergies are not common in dogs. As with anything, moderation is key! It’s very hard to formulate a nutritionally complete diet for dogs at home, so it’s safest to stick with soy as an ingredient in a good quality dog food. If you do wish to offer home-cooked meals, it’s important that you consult a veterinary nutritionist first.