Question
I own a 19-year-old Thoroughbred gelding. He’s so obese he looks pregnant, but his diet consists only of free-choice coastal Bermudagrass, a handful of barley, a handful of timothy hay pellets, rock salt, and seven acres of pasture grass to eat how he chooses as the season dictates. In spring and summer, I worry about founder. His coat has gone from short, tight, and dappled to long and somewhat curly. Most unusual, though, is his unquenchable thirst. Between him and his aged pasturemate, they can drink 60-100 gallons of water in a day. Something's up, and I want to know what. Any ideas?
Answer
I have come up with a few suggestions for weight loss while making sure your gelding receives required nutrients.
You didn’t mention the quality of grass in the pasture. With his need for weight loss, I imagine you keep him muzzled when grass is available, which may be for most of the year. During the spring, when grass is growing rapidly, you might consider using a drylot and maintaining him on an all-hay diet, as founder-prone horses often relapse during the spring flush, even when muzzled. If at any time this gelding shows tenderness of his hooves, he should be removed from the pasture immediately and placed in a drylot. A veterinarian should be called in promptly for consultation as well.
Free-choice Bermudagrass hay during the winter is meeting the gelding’s forage and energy needs. However, in the current management system, it is hard to restrict the amount of hay he consumes, and this can make weight loss difficult. If his pasturemate could also benefit from weight loss, you may consider getting a slow-feeder net for your round bale to decelerate consumption. Another option would be to get rid of the round bale altogether and offer hay in a more limited manner.
Also, if the Bermudagrass hay is premium quality, you may look around for some mid-quality forage. Horse owners revel in providing horses with green, leafy, premium-choice hay, but not all horses thrive on this. As with all hay fed to horses, it should be free of dust or mold, even in trace amounts, but it might be slightly more yellow than green, as though it was harvested at a later stage of maturity. Feeding this gelding 1.5% of his body weight in mid-quality hay will likely deliver all of the energy he requires for maintenance.
I would suggest adding the micronutrient supplement Micro-Max to this gelding’s diet. This concentrated source of vitamins and minerals will satisfy the missing nutrients in his all-forage diet. If you need to continue to feed the barley or pellets to act as a carrier for the Micro-Max, that’s acceptable. Otherwise, you can remove these items from the ration. For horse owners in Australia, use Gold Pellet.
In addition to calorie restriction, the most effective way to promote weight loss is to increase exercise, as just 30 minutes of structured, low-intensity exercise each day, such as walking and trotting, can help stave off metabolic diseases. Thoughtful management strategies can also help with exercise. For example, you can move the hay and water source to opposite ends of the paddock, so the horses are required to walk each time they desire a drink.
The change in haircoat and excessive thirst you describe, sometimes referred to as polydipsia by veterinarians, are well-known signs of Cushing’s syndrome or pituitary pars intermedia dysfunction (PPID), a metabolic problem caused by a tumor of the pituitary gland that results in increased cortisol production. Several diagnostic tests are available to help determine if your gelding has Cushing’s, but they must be performed by a veterinarian.
Based on laboratory results from these tests, clinical signs, and history, the veterinarian will be able to best advise how to proceed with treatment. Many horses that have a distinct change in hair quality, such as what your gelding is showing, are simply assumed to have Cushing’s. Some cases of Cushing’s can be slowed through the use of pergolide mesylate, known simply as pergolide.
