Milk samples are providing vital information about iodine levels in western Canadian broodmares — the focus of a study led by theriogenology specialist Dr. Claire Card of the Western College of Veterinary Medicine (WCVM). Iodine is essential for producing thyroid hormone and the normal function of the thyroid gland — a key factor in metabolism and the normal development of growing animals.
A newly-born foal
Researchers hope study will help them understand and prevent congenital hypothyroidism dysmaturity syndrome which results in the death of newborn foals.
© 2007 by Heather Smith Thomas
For horses living on the Prairies, there’s little information about iodine levels in the serum (blood) or milk of horses, or about their levels of seleni-um — a trace mineral that contributes to thyroid hormone production.
Members of Card’s team include theriogenology resident and graduate student Dr. Maria Lopez, epidemiologist Dr. Tasha Epp and summer research student Mikayla Swirski, along with Dr. Bernard Laarveld, an expert in effects of plant glucosinolates, and Dr. Nadia Cymbaluk — an equine nutrition expert.
In addition to milk samples, Card and her research team analyzed mares’ blood samples to determine iodine and thyroid hormone levels. They also used hair from the horses’ manes to assess the horses’ selenium levels. Preliminary analyses showed 73 per cent of the mares and 38 per cent of the foals tested from various farms had marginal or low serum iodine levels.
Twenty-two per cent of the mares’ milk samples had inadequate amounts of iodine, despite access to iodized salt blocks. As well, 88 per cent of mares were deficient in selenium.
“People spend a lot of money on feed. Horses, especially pregnant mares, aren’t getting what they need,” says Card. “Horse owners should consider getting a serum iodine, mineral panel, and mane hair selenium concentration [tests] done on their horses, because these deficiencies are so common in Western Canada.
”The researchers hope this study will bring them closer to understanding and prevent-ing congenital hypothyroidism dysmaturity syndrome (CHDS).
This disease, which results in the death of newborn foals, has been reported in Western Canada and in the state of Washington.
Previous WCVM research indicated that CHDS-affected foals suffer from primary hypothyroidism, a condition where the thyroid gland is unable to make sufficient amounts of thyroid hormone.
Researchers identified a lack of mineral supplementation and nitrate exposure as risk factors for CHDS. Nitrate is also known to suppress iodine uptake.Card and her team recently reported that dams of CHDS foals also have impaired thyroid function.
Although a mare carrying a CHDS foal will often appear healthy, her foal is born with serious issues including hypothermia, an overshot lower jaw, contracted tendons, severe bone defects, and sometimes an enlarged thyroid (goiter).
Card wants to understand how to prevent the disease, but researchers still need more information: “We need to know more about the levels of important minerals that affect thyroid function, such as iodine and selenium, along with and what role ingestion of toxic plants and weeds had in CHDS.
For complete article see horse-health-lines-spring-2019-online/
Article by Mikayla Swirski
Press release provided by Horse Health Online