tired on trail

Question
I have a 4 yo spainish barb/quarter palamino gelding named Lakota,who is in great health, although he does get 2 shots per month due to allergies. We started trail riding last spring with him and my spotted saddle paint who is now 7 yo. My problem is that he will start out fine, and about an hour later he will slow down some, then about 30 mins later, he is down to grandma mode, then he will just stop & will not move. When it first started to happen, I got off and lead him back to the trailer and he walked fine, no problems. I have changed all of his tack just in case something was pinching him, he is not sore anywhere. We take them out riding 2-3 times per week and he does this everytime. The last time he did it, my husband got on him & he had the whip and he bucked one time & they went. My husband thinks that I am just not firm enough with him to get him to go. My paint, starts and ends in the same walk and only slows down when she is behind me & Lakota. He is on safe choice and also have a mineral block, he is not over weight--is he just giving me a hard time??? My farrier was out today & I told him what he was doing and he sided with my husband, I also asked him about giving him supplements, thinking maybe he was lacking something, and he told me that he didn't think he needed any. He is about 16.3 hands and he is kind of wide and stockie. As many times as we have been trail riding, I would think that we could go at least more then 1 1/2 to 2 hours. The trails we go on are not that bad, some hills but not real step. I just don't understand the probelm, any help would be great.

Answer
Teresa,

There could be a number of things going on here.  I am going to suggest you get him checked out by a vet, especially some bloodwork and check out his heart.  You may well need to get several blood panels done to determine what, if anything, is going on.  You may also need to have some blood gas and lung volume studies done.  All this depends upon what the initial exam by the vet shows.  

If you rule out everything physical then you do have a behavioral problem but my gut feeling is no.  I know this sounds expensive but this is one of the things associated with animal ownership unfortunately.  You need to know what's going on.  Also be aware that he is still very young and you are riding him for what I consider too long a time.  He still has 4 more years to grow, until his skeleton is fully grown.  I try to keep time on a horse's back as a 4 yr. old down to no more than 1.5 hrs. and that's at the end of their 4th yr. after they've been conditioned.  I want my horses still useful well into their later years and arthritis free so give them time to grow and mature.  I saw first-hand what happens in Thoroughbreds when I was a pre-vet student at the University of KY. and worked in the animal necropsy room.  You know how young TB's are when they start them.  We got a lot of older ones in to post and the changes in their spines from weight carrying as youngsters was not pretty.  Dr. Deb Bennett did a study some years ago and determined that the bones of the spine are some of the last to ossify.  So keep that in mind when riding.  

Let me know what the vet says, this has reminded me of a horse a friend of mine had that would lay down on the trail and sleep for 15-20 min. then get up.  He turned out to have a heart problem.  She had a lot of work done before they finally figured out what his problem was.  He had to work on a high-speed treadmill to bring about a repeat of the behavior in the clinic that he did on trail.  

Lyn