X-Small
Back Length: 18cm/7in
Chest: 36cm/14in (Most Important)
Neck: 32cm/12in
Recommended Weight: 2-13lb/1-6kg
Small
Back Length: 25cm/9in
Chest: 44cm/17in (Most Important)
Neck: 36cm/14in
Recommended Weight: 13-17lb/6-8kg
Medium
Back Length: 31cm/12in
Chest: 54cm/21in (Most Important)
Neck: 43cm/16in
Recommended Weight: 17-48lb/8-22kg
Large
Back Length: 38cm/14in
Chest: 62cm/24in (Most Important)
Neck: 48cm/18in
Recommended Weight: 48-61lb/22-28kg
X-Large
Back Length: 43cm/16in
Chest: 72cm/28in (Most Important)
Neck: 54cm/21in
Recommended Weight: 61-88lb/28-40kg
2X-Large
Back Length: 48cm/18in
Chest: 82cm/32in (Most Important)
Neck: 62cm/24in
Recommended Weight: 88-110lb/40-50kg