The Horse

MAR 2019

The Horse:Your Guide To Equine Health Care provides monthly equine health care information to horse owners, breeders, veterinarians, barn/farm managers, trainer/riding instructors, and others involved in the hands-on care of the horse.

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22 March 2019 The Horse | TheHorse.com right now, and every single one has a heart murmur," he says. As they become more malformed and develop greater pain and loss of movement, these horses become more sedentary, says Eberth. This inactivity interferes with digestion and general musculoskeletal health, and it has severe consequences on the welfare of an animal that's evolved to move almost constantly. "With combined digestive, musculoskel- etal, and hoof issues, these dwarfs get into a snowball effect, and there's just no stopping it once it's started," he says. Life expectancy in equine dwarfs varies considerably, depending on the extent of the malformation and the care. "Some die in the first year; others can live up to 15 years," says Eberth. The Dwarf Diet As we know, feeding the dwarf can be a challenge due to having the nutritional needs of a full-sized Mini compacted into a tiny frame. There's also the issue of these horses' jaw and dental problems. "Some of them can end up with a mash or liquid diet, but these animals can sec- ondarily starve to death because they're not getting enough nutrients to survive," Eberth says. "These individuals are often very thin and have a lot of gastrointestinal tract issues." Though many appear to be "fat," it's important to remember that the big belly comes from bulging organs, not obesity. "We feed ours an amazing amount of food," Dolan says. "It's surprising how much they need to eat." And for those frequent dental-care vis- its, they need skilled dental professionals, adds Barrett. "It's not always easy because they're so small," she says, adding that not all practitioners have the appropriate equipment. Miserable Little Feet Dwarf feet are true victims of their cartilage protein-affecting mutation, says Eberth. Like the organs, the hooves themselves start out healthy and nor- mal. While they're not compacted by a skeleton, they're still linked to the bony structure inside the foot. And as the foal grows, the bone wreaks havoc on the sur- rounding tissues. "The coffin bone (which is within the hoof capsule) becomes malformed, the joints fuse, the limb bones grow abnor- mally, and all that puts all the angles out of alignment," Eberth says. Indeed, along the whole length of the leg, all the way down to the pointed coffin bone, dysfunctional bone growth has serious repercussions in the hooves. The growing feet try to compensate for misalignment and asymmetries of the abnormally shaped bones within. "They curve and hook and twist and grow side- ways and develop club feet … It's a mess," Eberth says. Interestingly, he adds, these dwarfs rarely have laminitis. "It can look like laminitis, and people sometimes confuse it for laminitis," he says. "But it is the disease progression of the limb deformi- ties in the dwarf Miniatures restricting movement and causing pain." Dolan says good corrective shoeing works wonders for these little feet. "We use polyurethane shoes that we glue on to the front of the hoof," he says. "And we often use an extensor that allows them to have a lot of support, and this strength- ens their ligaments in a healthy way and makes them more comfortable." Managing the feet correctly from the beginning helps keep things straight and supported as the dwarf grows. "It's a lot harder to fix once the joints close up and the tendons (finish developing)," he says, which occurs by the time they're 2. Responsible Breeding Again, they're adorable and cuddly, but that's no reason to aim for one. "Back in the '80s, some breeders of Minis thought these were the ideal Mini and started se- lecting for them, without understanding their pathology (disease)," Eberth says. "Dwarfism skyrocketed, with detrimental effects on the breed." The mutations are recessive, but the odds of it manifesting are still fairly high. "If you breed two healthy carriers of a dwarf mutation, you'll have a 25% chance that the offspring is a dwarf," he says. Fortunately, genetic testing now exists. "You can safely breed a carrier to a non- carrier and not have a chance of produc- ing a dwarf," Eberth says. "So you don't have to scrap your breeding program. You just need to make wise and informed decisions. Educate yourself as much as you can—about the disease and about your own breeding stock." Take-Home Message Unlike the magical creatures of fan- tasy in German fables, Miniature Horse dwarfs do not have special powers—aside from stealing people's hearts. They're pre- cious, but these animals' genetic condi- tion puts them at a high risk of health and welfare issues, and their care is both time-consuming and expensive ("We're talking thousands and thousands of dol- lars per year," Eberth says). While researchers are still uncovering the extent of these equids' health prob- lems, current goals are to treat existing dwarfs as early as possible and to prevent the birth of new dwarfs through genetic testing and responsible breeding. h DWARFISM: NOT A SMALL PROBLEM Dwarfs have notoriously malformed and painful feet. The Peeps Foundation's farriers apply polyure- thane shoes to the hooves to correct and support them.

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