If your dog eats aloe vera, watch for signs of poisoning such as vomiting, diarrhea, or lethargy. Aloe vera contains chemicals that can harm dogs when eaten. Contact your veterinarian immediately for guidance. Tell your veterinarian how much aloe vera your dog received and any symptoms that occur. Also, make sure your dog drinks plenty of fresh water to stay hydrated. Keep the aloe vera plant away from animals to prevent accidental ingestion in the future.