Why Mouths deteriorate on Horses. What are the reasons for the mouths of horses to progressively deteriorate after being handed over to the owner by the ‘Breaker’? They almost always do, some more than others and some, totally. Lets say the mouth of the horse is finished at a 9-10 when it is handed back to the owner. From that day forward, unless the owner is a professional rider, the mouth of that horse will diminish for various reasons and end anywhere between zero and about 6.5. I rarely meet one over that mark. So what are the causes of this? Having [...]