sluggish horse

Question
I have an 18 yr old appy mare, I have had her for about 8 months, she was in a pasture and handled by small children for the past 4 years.  When I first got her she was a little overweight, the vet checked her and said teeth and feet were good and wasn't concerned about her weight.  Since then I have been riding her more and more every week, we take an hour lesson once a week, I will ride in the arena once or twice a week, sometimes take her for a couple mile ride outside on the rode, and now that the weather is getting nicer we trail ride at least once a week, sometimes twice a week. we do go for fairly long trail rides, at first she seemed to have plenty of energy and was doing well she has been loosing some weight, (not sure how much exactly)so my trainer noticed it and said to up her calorie intake she now gets 4 pounds senior grain 2 flakes alfalfa and 2 flakes grass hay, plus a supplement for joint, and digestion.  Last weekend the weather was warm around 75 to 80 and we rode for 5 hours,(which she has done many times) with some breaks for grass and water that she refused to drink, we rode again the next day for only a couple hours but from the very beginning she was acting sluggish, no energy.  Oh ya she tends to be a lazy horse by nature and sometimes I really have to push her to make her go past a walk or trot, I became concerned when she would not/could not stay at a lope when her other horse buddies were loping and getting to far ahead, shes some what heard bound and on the trails doesn't let her friends get to far out of sight so I became concerned at that point
I have been increasing our riding time over the last several months to build up her stamina and not over work her all at once, we eventually want to trail ride 3 times a week, some times we will go 2 days in a row, she will stay at a friends overnight that lives close to where we ride and or we will camp and take them with us.  I don't want a different horse right now I am a fairly new rider and she is a good sound horse that is well broke,she is level headed, doesn't spook. been on hundreds of trail rides and packed on many trail rides.  I don't think she has any physical problems, but concerns about weight loss due to over riding and or dehydration are a concern,and have been suggested by others. what can I give her on the trails to help with dehydration if that is the problem, when she wont drink? and, am I feeding her enough for the amount of time I'm riding her? she seems to be building a lot of muscle in her front but her back end is till some what flabby, her previous owner says she looks great but did notice the weight loss.  I did recently have her adjusted by a chiropractor
Thanks
Teresa

Answer
Hi Teresa,  I'm not really concerned by what you have explained.  My horses don't always drink when I think they should (like after a hard ride) but that doesn't mean they're dehydrated or will become dehydrated.  You can mix electrolytes with her grain or in her water.  I've had more success with adding it to their grain.  You can also mix Gatorade in with her water while on the trail if your camping and she's drinking out of a bucket.  She may not like the Gatorade but sometimes they'll drink it.  Her weight loss doesn't concern me because it sounds like you are riding a whole lot which would cause the weight loss.  I would feed her the ration you described 2 times a day if you're not already.  You can also feed her rice bran along with her grain as it's a good source of fat.  If your concerned about her water intake you could wet her feed and make it soupy to add a little extra water.  You can also feed her soaked beet pulp, that's a good source of fiber plus it adds water also as it has to be soaked before feeding.  I would feed about 1-3 quarts with grain.  You can try adding red cell (an iron supplement) to her grain.  You can get it at almost any feed store.  Vet's will say it won't do anything if they're not anemic but from my experience it just depends on the horse.  It's purpose is to give one more energy.  I think the lethargy on the trail has to do with her being lazy like you said and being 18.  18 is considered to be a senior age for horses.  She's probably so relaxed with her job because she's a seasoned trail horse that she just doesn't exert the extra energy.  I've had plenty of horses who are under the age of 5 who are fit give out on a trail or hunter pace where we will be cantering quite a bit.  It's only because they need a break and are just not motived like a TB or hotter type horse would be. When that happens don't push her and let her have a break.  It sounds to me like you have a very fun horse.  If you have more concerns contact a vet, they can pull blood that will tell if you she's anemic or dehydrated.  Good luck!  Jessica