Unlike some other nuts, peanuts do not contain substances that are toxic to dogs. However, they are very fatty and may cause digestive upset or allergic reactions. A small amount of unsalted, raw peanuts can sometimes be given as a rare treat. Regular feeding is not safe - it overloads the pancreas and liver, and can lead to vomiting, diarrhea, and weight gain. Salted peanuts, peanuts in glaze, or with spices are dangerous for dogs.
Peanuts for cats
Peanuts offer no benefit to cats. Due to the high fat content, they can cause stomach and intestinal problems. Cats, as carnivores, cannot digest nuts the way humans do. There is also a risk of allergic reactions. It is better not to give peanuts to cats at all, even as a treat.
If your pet eats a large amount of peanuts and shows vomiting, diarrhea, or lethargy, contact a veterinarian as soon as possible.