Rare
OTHER DIAGNOSES CONSIDERED
Other conditions or ailments that might also need to be ruled out by a vet.
Diagnosis
Conditions or ailments that are the cause of a problem that you see - your observation.
Your vet may diagnose
Benign Enlargement of Thyroid Gland
Synonyms: Goiter
Summary
Enlargement of the thyroid gland in the throat region is fairly common in older horses. In most cases, the cause is benign (non-cancerous).
Enlargement of the thyroid gland is often called "goiter". This term is confusing, because it generally means that thyroid enlargement is caused by elevated amounts of iodine in the diet. In human medicine, this is a common reason for thyroid enlargement. Horses with iodine excess (usually from overfeeding of iodine) may also have an enlarged thyroid. In rare cases, foals are born with a congenital enlargement of the thyroid gland.
Benign thyroid enlargement may be differentiated from true goiter via ultrasound appearance and blood iodine testing. In most cases, the diagnosis is made presumptively (without any further diagnostics). Ultrasound and/or biopsy of the mass is used to rule out thyroid cancer. In some cases, testing blood iodine levels may be helpful if true goiter is suspected.
Goiter in the horse is rare enough that I do not discuss it further here. Benign thyroid enlargement is usually not considered a problem and you and your vet simply will monitor the growth, without any treatment.
There is no recommended treatment for benign thyroid enlargement. However, in some cases the masses can become quite large. Although unsightly, usually these masses do not seem to bother the horse.
Enlargement of the thyroid gland is often called "goiter". This term is confusing, because it generally means that thyroid enlargement is caused by elevated amounts of iodine in the diet. In human medicine, this is a common reason for thyroid enlargement. Horses with iodine excess (usually from overfeeding of iodine) may also have an enlarged thyroid. In rare cases, foals are born with a congenital enlargement of the thyroid gland.
Benign thyroid enlargement may be differentiated from true goiter via ultrasound appearance and blood iodine testing. In most cases, the diagnosis is made presumptively (without any further diagnostics). Ultrasound and/or biopsy of the mass is used to rule out thyroid cancer. In some cases, testing blood iodine levels may be helpful if true goiter is suspected.
Goiter in the horse is rare enough that I do not discuss it further here. Benign thyroid enlargement is usually not considered a problem and you and your vet simply will monitor the growth, without any treatment.
There is no recommended treatment for benign thyroid enlargement. However, in some cases the masses can become quite large. Although unsightly, usually these masses do not seem to bother the horse.
my vet's role
Diagnostics Used
These are tests that might be helpful to make this diagnosis or further characterize the condition.
Treatments May Include
These treatments might be used to help resolve or improve this condition.
PROGNOSIS AND RELEVANT FACTORS
The prognosis for benign enlargement of the thyroid is very good, although the masses can become very large and unsightly.my role
I might observe
You might make these observations when a horse has this condition.
Skills I Might Need
I might need these skills if my horse has this diagnosis.
Questions To Ask Your Vet:
- How can you be sure this is benign and not cancerous?
- Is this related to iodine excess or deficiency?
Prevention
There is no known prevention. In cases where iodine is thought to be involved, ensuring appropriate levels of iodine in the diet will help remedy the thyroid enlargement.
Related References:
Smith, BP ed. Large Animal Internal Medicine 4th ed. St. Louis: Mosby Elsevier, 2009.