The most popular patterns and big dog shirts prints for pet clothing include classic plaids, playful polka dots, and chic animal prints like leopard or zebra. Florals are a favorite for spring, while festive designs like snowflakes and pumpkins dominate holiday seasons. Trendy options include tie-dye, camouflage, and personalized prints featuring pet names or quirky slogans, making pet fashion both stylish and fun.