Dogs should not eat watermelon rind. While the rind is not toxic, it is very tough and difficult for dogs to digest. Eating watermelon rind can cause digestive upset, choking hazards, or even intestinal blockage, which can be serious especially for smaller dogs. It is best to always remove the rind before giving watermelon to dogs. If a dog accidentally eats watermelon rind, it is recommended to call a veterinarian and monitor for symptoms such as diarrhea, lethargy, or signs of stomach pain, as medical intervention may be necessary.