Focus on waterproof ratings (measured in mm); a professional-grade dog raincoat should have a rating of at least 3,000mm to 5,000mm. Ensure the fabric is breathable (e.g., TPU coating or mesh lining) to prevent canine overheating. Key functional features include leash portal access, 3M reflective strips for night safety, and adjustable belly straps to accommodate various breeds. For durability, prioritize ripstop nylon or high-density polyester with heat-sealed seams to prevent leakage at the stitching points.