Pistachios are bad for dogs in large amounts because they contain fat and salt. The ASPCA recommends feeding a dog only one pistachio once in a while; otherwise, vomiting and diarrhea may occur.
Pancreatitis, or an inflamed pancreas, is also possible if a dog eats too many pistachios, adds the ASPCA. Pancreatitis can be brought on by consuming foods that have high levels of fat. Sodium ion toxicosis can occur if dogs consume too many salted pistachios.
Dog owners need to remain vigilant with regard to mold on pistachios and other nuts, warns Paw Nation. The aflatoxins in mold can cause many issues, such as liver failure.