Lydia, my sweet Lydia, for most of her life was the mare who could gain weight simply by having a feed bag waived in her general direction, never mind that she emulated the Energizer Bunny.  However, she's 29 now, and for the past year or so, keeping weight on her has been a challenge, and she's been slowing down. 

I talked to friends with older horses, both online and off, in search of ideas.  I experimented with the suggestions that I received from them, tweaking until I had a recipe that came close to working - she didn't lose weight, at least, though she was still under ideal and moping around a bit.  That was a combination of Equine Senior, rice bran, vegetable oil, and apple cider vinegar (for her arthritis), mixed up at every meal and wet down to take into account her teeth that were also 29 years old. 

I fretted over her appearance, though our vet commented on how good she looked and, when I protested, pointed out, "She looks damned good for a 97-year-old woman!"  Point taken, but still I fretted.

One evening, as we were driving home from a night out, a lightbulb floating over his head, my husband said, "Why don't you give her beer?" 

Well, it puts weight on people . . . so I tried it. 

When we got home and I went to feed, I pulled a Shiner Bock (what we had readily available - I use it a lot in cooking) out and used it, instead of water, to wet down her food.  I eliminated the vegetable oil and apple cider vinegar. 

I've rarely seen a feeder licked cleaner.  My reception, the following morning at feeding time, was distinctly more enthusiastic than it had been of late (and this from a mare whose enthusiasm for her food has earned her the title of "The Tallest, Prettiest Pig In the World"). 

However, Shiner Bock was going to be pretty pricey for a horse, so I went out, researched, eliminated the lite beers (hello, we're trying to gain weight here!), and purchased the cheapest I could find, a case of cans of Lone Star Beer (appropriate for a mare living in Texas, I thought).  Lydia turned out not to be a connoisseur of fine beers, and we were set. 

These days, the old, grey mare, she ain't what she'd become.  I go outside in the morning, or late in the afternoon, and there is neighing from the pasture or paddock.  When I bring the bucket with her feed, as I'm walking to the paddock, rather than standing desultorily by her feeder, she's trotting briskly from one end of the fence to the other, nickering at me to "hurry up!" and going to her feeder and back to me to make sure that I haven't forgotten where it is.  On two beers a day, morning and evening, she's putting on weight, her arthritis is no longer a problem to her (or if it is, she's showing no signs of it), she's once more very enthusiastic about her feed and life in general.

As Phil says, "She's 29.  She's retired.  If we end up creating an old, fat, happy, healthy. tipsy horse, where's the harm?"