My spaniel Newton was impossible to measure accurately, when I phoned Mountain Dog for advice with the rough measurements that I had achieved, the person I spoke to suggested the 45cms instead of 50cms that I was asking for and suggested that I bought both sizes and returned the one that didn't fit for a refund. The Monsoon coats were delivered very quickly, in time for the recent very wet weekend and the young man was right, the 45cm one was perfect, Newton was a very happy dry dog, and I didn't have much cleaning up of muddy dog. Also, the coat that I returned was refunded very quickly. Thank you. Angela W