Hostas are a garden favorite for shady areas; they make a lush display of greenery. But any part of the hosta plant -- leaves, flowers and roots -- can cause misery or worse to a dog if he eats or even chews on it.
What's Dangerous About Hostas?
What makes the hosta dangerous is a chemical substance it contains called a saponin. The name comes from the Latin "sapo," soap; you can actually make a soaplike cleansing substance from the soapweed yucca (Yucca glauca) by using the pounded root, and from common soapwort (Saponaria officinalis) by using the chopped leaves and stems. Both plants contain enough saponin that, when agitated with water, it foams up. Hostas don't contain enough saponin to make soap, but they contain enough to make them harmful to dogs by this foaming action.
What Does It Do to Dogs?
If a dog ingests saponin, whether from eating hostas or food that contains saponins, it stops the dog from vomiting, fills his stomach with foam and can even paralyze his intestinal tract so that for a while he can't get rid of his problem from either direction. At the very least, he'll look miserable and show signs of a severe bellyache and eventually will vomit and have diarrhea. Some experts feel that in large dogs and giant breeds such as Great Danes and Irish wolfhounds, eating saponins can lead to bloating and even twisting of the stomach or intestines, which creates a surgical emergency.
How Can I Protect My Dog?
Keep your dog away from hostas if he seems to have a desire to nibble on them. Dig them out of any fenced area he has access to on his own, being careful to remove all the roots, and keep him on the leash on walks so he can't get at the neighbors' gardens. If you're worried about saponins in his food, take him off store-bought kibble, which may contain naturally occurring saponins in some of its ingredients, such as soybeans, beet pulp, oats and beans.
What Can I Substitute?
Replant your garden with shade-loving plants other than hostas, such as violets, begonias and impatiens. If doing this is impractical, consider building a separate dog run -- and plant only dog-friendly foliage there. Replace the kibble in his diet with homemade dog food, including beans, as long as they are presoaked overnight and slow-cooked in several changes of water to remove the saponins.