Most apparel factories use one basic coat block and simply scale it up or down by weight. A French Bulldog weighing 12kg has a wide chest, a short back, and almost no neck. A Dachshund at the same weight is long, narrow, and low to the ground. Scaling one coat pattern to both breeds produces a coat that fits neither. Customers return it. You lose money. The factory blames your spec.
A lot of waterproof dog coats on the market use PFAS-based DWR (Durable Water Repellent) coatings. These chemicals are persistent, bioaccumulative, and under increasing regulatory scrutiny. More importantly, dogs lick their coats. If the waterproofing chemical is toxic, the risk lands directly with your customer. Many general factories cannot tell you what chemical process they use | let alone provide a test report.
You want to launch 4 coat styles to test the market. At 1,000 pieces per style that is 4,000 units to fund before you know what sells. Most small brands either give up or cut corners by going with uncertified factories that do smaller runs. Neither outcome is good for your brand.
A dog wearing a coat still needs to wear a harness. If the coat has no D-ring hole or harness opening, the owner has two options: remove the coat to attach the lead, or skip the coat entirely. A surprising number of factories produce dog coats with no consideration for how dogs actually get walked. The product fails in real life even if it looks fine in photos.
Here is what dog coat manufacturing looks like when it is done right.