Pet experts at Veterinary Pet Insurance recommend never feeding almonds or any kind of nuts to dogs. While almonds are not toxic to dogs, they do upset a dog's stomach because dogs are not able to digest them well. Almonds tend to move slowly through a dog's gastrointestinal tract, which leads to stomach irritation.

In addition to almonds, there are several varieties of nuts that cause severe stomach distress in dogs. Some of these nuts pose a fatal risk to dogs.

The ASPCA points out that macadamia nuts are high on the list of foods that dogs should never eat. According to Web MD, eating up to six macadamia nuts causes rapid heart rate, tremors, vomiting and severely weakened back legs among other symptoms. Dogs may be very ill for up to 48 hours after eating the nuts.

According to Veterinary Pet Insurance, black walnuts, English walnuts and Japanese walnuts contain various levels of toxins that pose a risk to dogs. When mold forms on walnuts, it releases toxins that cause dogs to experience neurological symptoms and seizures. Without the mold, walnuts are similar to almonds in causing intestinal blockage and stomach upset.

Other popular nuts that people love but which dogs should never eat include hickory nuts, pecans and pistachios, per Veterinary Pet Insurance.