Question
My mother’s 25-year-old mare has an enlarged thyroid. The mare does not gain weight despite consuming two to three times more senior feed than is recommended for her size. I believe her inability to gain weight has something to do with the thyroid, which has grown steadily over the last few years. Is overfeeding making the problem worse? We've had the vet look at her, but I'd appreciate any feedback or suggestions.
Answer
Without knowing more details about the mare’s health problems, it is difficult to determine the best approach for weight gain. Deeper investigation into the swelling, with more diagnostic tests, would likely help pinpoint the problem and may provide greater insight into the weight issue. An opinion of your mare’s health by a second veterinarian may also help put you at ease.
While waiting for further testing, taking inventory of iodine levels in the current diet is a good place to start, as excess iodine could cause thyroid enlargement. Nutritionists need to know a horse’s complete ration before iodine consumption can be estimated. For instance, what senior feed is the mare given, and how much is she fed? Does she get any additional supplements? Is salt top-dressed onto her feed? Is she fed an electrolyte supplement or a seaweed supplement? Does she lick or gnaw at a salt block more than other horses? You’ll have to furnish these details, and others concerning her forage intake, before I can ascertain if she’s consuming too much iodine.
Feeding strategies are also important for senior horses. Anytime horses are fed more than about 5 lb (2.3 kg) of feed per day, the total amount should be broken up into two or more meals. The feeding rates on some senior feeds can be quite high (up to 1.5% of body weight depending on forage intake), so be sure to split the total amount into three or more meals a day. Also, ensure she has access to good-quality, free-choice forage at all times, if her teeth are still serviceable. Depending upon the condition of her teeth, you may want to try adding some short-stem fiber like hay cubes or pellets. Increasing caloric intake of meals without adding more feed can be done by introducing a fat source, such as vegetable oil or stabilized rice bran.
Another consideration is providing support for the hindgut with specialized supplementation. EquiShure works to maintain a more stable pH environment in the cecum and colon, collectively called the hindgut. This is an important part of the digestive tract because it handles fiber fermentation and digestion. EquiShure supplementation has benefited many horses that have not been diagnosed with acidosis but present with suboptimal digestive health and function, including lack of appetite and weight loss. EquiShure helps to balance the environment and promote a healthy microbial population.
