There are some people foods that are harmful to dogs, and some are likely to be in your hiking pack! Here are some typical hiking foods to avoid giving to dogs.
Raisins and Grapes
Many trail-mixes have raisins. The very acronym, GORP, stands for “Good Old Raisins and Peanuts.” Grapes and raisins can cause kidney failure for dogs. Even a small amount can make a dog ill. Vomiting is an early symptom, followed by depression and low energy. I have been told stories of dogs dying from only a handful of grapes. I wouldn’t know, I haven’t tried it and never will.
The most dangerous types are cocoa, cooking chocolate and dark chocolate because they have the highest levels of theobromine. The danger is higher with smaller dogs, but even a few ounces of dark chocolate can cause tremors and stomach disorders. Rather than figuring out which chocolates are high in theobromine, just nix all chocolates for your dog.
Not all nuts are bad, but the worst are Macadamia nuts and to a lesser extent, Almonds and some others. Peanuts seem to be OK but much better in peanut butter form. Smaller dogs can choke on larger whole-nuts like almonds, but it goes beyond that. If your dog gets into a bag of nuts, it is best to get to a vet in a hurry. Signs of distress include vomiting, diarrhea, coughing and choking. If your dog eats just a few nuts and is OK several hours later, the danger may have passed.
Ingesting even small amounts of macadamia nuts can be lethal to a dog. Symptoms include muscle shakes, vomiting, increased temperature, and weak back legs. The combination of macadamia nuts and chocolate is even worse.
Many salty snacks are also not great as too much salt can cause dehydration, but that is true for humans too. I don’t take salty snacks on hikes, so I have no issues there.