I believe you meant "Horse Latrine" or more commonly referred to as "Horse Toot" or simply a play on words "Horse Tube" could relate to an informal term. However, I'm assuming you are referring to a colloquial or humorous term 'Horse Toot'.
In a more serious context, if you are referring to "Horse Tube" as in a structure or medical term, there isn't a widely recognized term as such. shemale horse fuck tube
In equine care, managing gas and digestive health is crucial for the well-being of horses. This can involve diet management, providing plenty of fresh water, and ensuring they have adequate exercise. I believe you meant "Horse Latrine" or more