Omega-3's may benefit your dog's heart, joints, skin, immune system, and more. Your veterinarian may recommend a specific amount of EPA, DHA, or other omega-3's depending on your dog's issues. If your dog is itchy or you are simply looking to support skin and coat health in your dog, you'll want to give about 180 mg of EPA and 120 mg of DHA for every 10 lbs. of body weight.