The largest coat we make is an S 10. Check the large for the sizing chart. After that, we need your measurements. Our measurement chart is available under the Custom order tab. go to #2, to download the chart..very handy to have an extra one. The S 10 will fit a Bouvier, large GSD, Black Russian terrier.But these dogs can vary in size, so best to check measurements. Chose the custom tab when ordering. We can make them in any color that we have fabric in, so have fun with it. They can be styling, and healthy with our coats. Remember they last 10 years. All our fabrics resist dog hair and are washable.