Poison ivy (Toxicodendron radicans) is a woody vine that produces a toxic resin called urushiol, which causes intense itchiness and raised rashes when it comes into contact with skin. This plant grows all over the United States and is identifiable by its bright green color and distinctive three-leaf structure. While a dog’s hair coat provides some physical protection from poison ivy, exposed areas where hair is thin or absent, such as the belly, inner legs, external genitalia and muzzle, can be affected. Short-haired and hairless breeds are at increased risk. Contact between poison ivy and the skin causes severe dermatitis. Dogs itch, scratch, lick, chew and bite at their skin, developing open sores and raised red patches that may blister and weep. If a dog eats poison ivy, its mouth and throat can become irritated and inflamed. It can also develop a terrible tummy ache and become extremely sick.