Hibiscus plants are toxic to dogs, according to the American Society for the Prevention of Cruelty to Animals. Hibiscus plants can cause vomiting, nausea, anorexia and diarrhea. Hibiscus is also toxic to cats and horses.
Ingesting hibiscus can also result in blood in the dog's vomit or diarrhea. According to Dr. William Buck, the loss of so many fluids makes this potentially lethal. Hibiscus is also known as the rose of Sharon and the rose of China. Hibiscus plants are known for their bright colors, and they grow to an average of 2 feet tall, but they can grow taller. The hibiscus has glossy leaves and grows best in sunlight.