Ms. Shaw, a freelance photographer who lives in San Diego, was on medication for irritable bowel syndrome, migraines, allergies and recurring sinus infections when she learned about the health benefits of a plant-based diet. She decided to go vegan, abstaining from meat, fish, eggs, dairy and other foods made from animals.

On the new diet, her health improved so much that she wondered if Portland, her golden retriever who was suffering from bouts of diarrhea and itchy hot spots on the skin, could also benefit from a vegan diet.

She switched him from a meat-based dog food to v-dog, a vegan kibble that uses a pea-based protein and forgoes corn, soy and wheat, and saw his symptoms clear up. She supplements his diet with homemade smoothies and vegetables.

“He’s a cancer survivor, and he has way more energy than ever,” she said of Portland, who now has a clean bill of health.