Connie Dorsch has been breeding Warmblood horses for more than 30 years and she’s never had a wreck like this.
She has lost four foals and one mare, and it’s taking an emotional and financial toll.
“It’s hard to have buried five horses in two months when we’ve never buried five horses ever,” she said from Weyburn, Sask.
Dorsch said each foal would have sold for about $10,000. As well, she estimated each dead animal cost her $6,500 in veterinary bills and the investment she made to get the foals on the ground.
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She doesn’t know what caused the problem. The foals were born deformed, with lower jaws that stuck out and front legs that wouldn’t straighten. Dorsch saved one foal with milder symptoms after administering medication and bandaging its legs to help it stand.
She suspects the problem was a new source of hay she fed the pregnant mares last winter.
Gail Lee, who has bred registered Paints at Hawarden, Sask., for 17 years, didn’t buy new feed but she has a similar story. She lost her one and only foal last year and three of four this year.
The foals were born with the same characteristics as Dorsch’s.
“It’s pretty devastating,” Lee said.
Andy Allen, a veterinary pathologist at the Western College of Veterinary Medicine in Saskatoon, says Dorsch and Lee’s foals were hypothyroid. He has studied the condition since 1990 and while he knows it is not hereditary, he doesn’t know exactly what causes it.
“These foals are born after normal, sometimes abnormally long, gestation,” he said, yet they look immature.
Those that do have enough strength to stand often rupture a tendon in their legs, he said.
“If a foal is able to at least stand up on its own, then it’s worth it to maybe support them, treat them,” he said.
“If they cannot stand on their own, you’re probably best to cut your losses early.”
These foals are often unable to nurse so they die from bacterial infections.
The mares have difficulty giving birth because the foals are weeks overdue and large.
Allen said something interferes with the fetus’ thyroid function during pregnancy to cause these problems.
Typically, mares carry foals for 330 days. As part of his research, he did fetal surgery to remove the thyroid at 215 days. The foals were born with the abnormalities seen by Dorsch and Lee.
Allen’s research points to high nitrate levels in feed fed to mares as a probable cause, especially if the horse’s diet is already deficient in iodine. Iodine deficiency causes hypothyroidism in people and studies have found that nitrates will do the same.
“I really believe that the feeding of forages that contain nitrate, especially if a source of nitrate is fed in the absence of good mineral supplementation, is the cause,” he said. “It might be the feed; it might be the water. Greenfeed is notorious for containing higher levels of nitrate.”
Hypothyroidism in foals is a predominantly western Canadian disease, first recognized about 20 years ago.
“This year seems to be a particularly bad year,” Allen said.
He added that nitrates are present in all plants at certain times. Hay plants absorb nitrogen through the soil and at one stage that nitrogen takes the form of nitrate.
“If that happens to be the time you harvest, your hay will contain nitrates.”
He recommended producers test their feed and water so they know what level is present.
