Question

I have a 34-year-old Quarter Horse gelding. He is in good health but has a growth, about the size of a golf ball, under the skin on the right side of his throat just behind the jaw. My vet has examined it and says it is not attached to the bone, not malignant, and should not bother him, perhaps a goiter. She considered it solely cosmetic. I would like to know the causes of this type of growth and if there are any supplements that have been successful in reducing the size/growth of such a growth. I am looking for a natural treatment which addresses the cause. I do not want meds that simply treat the symptoms.

Answer

The primary question is whether the lump is indeed involved with the thyroid gland. If the lump is in the thyroid and it is goiter, then the enlargement is likely from an iodine deficiency or excess. If the horse is on a formulated feed, there is little chance of iodine deficiency. Excessive iodine is common in horses that are fed kelp or seaweed, or being given some kind of iodine supplement.

The only thing you can do nutritionally is to have a ration evaluation performed to assess iodine levels. If an iodine deficiency is uncovered, an all-purpose vitamin and mineral supplement would likely correct the imbalance. On the other hand, if excessive iodine is found in the diet, superfluous iodine in the diet can be eliminated.

If goiter can be ruled out, your gelding may have a benign thyroid gland enlargement (nonfunctional thyroid adenoma). These are very common in older horses and are usually only a cosmetic problem. Only rarely will the masses affect swallowing or head carriage and require surgical removal. No treatment is necessary or very effective, and the mass should be observed for any changes in size.

One of the nutritionists at Kentucky Equine Research has a horse that presented several years ago with a similar lump, and her veterinarian said that it was not unusual for the structure that supports the thyroid gland to slip, thus allowing the gland to become more noticeable. Her gelding has had the lump for almost 20 years, and it has never bothered him a bit.

Working with your veterinarian or a veterinary team is the best way to ensure your horse’s well-being. If you would like a ration evaluation performed on your horse by the experts at KER, fill out this form.