Hi, Robin and welcome to the forum.
The following website is an excellent source of information on plants that are toxic to animals:
Here is what it says about the hibiscus plant:
Additional Common Names: Rose of Sharon, Rose of China
Scientific Name: Hibiscus syriacusFamily: Malvaceae
Toxicity: Toxic to Horses, Toxic to Cats, Toxic to Dogs
Toxic Principles: Unknown
Clinical Signs: Vomiting, diarrhea, nausea, anorexia.
"The animals share with us the privilege of having a soul." -Pythagoras
"The soul is the same in all living creatures, although the body of each is different." -Hippocrates
"Let us be loving, hopeful and optimistic. And we’ll change the world." -Jack Layton
"Be the change you want to see in the world" -Gandhi
Kitties: Punky (17), and Sassy (13), Twinky (10),
1991 to May 24, 2009