When a newborn foal falls seriously ill, every hour of uncertainty can feel like an eternity for owners and veterinarians. But researchers at North Carolina State University may have found a faster way to identify which foals need urgent help. Their study, published in the Journal of Veterinary Internal Medicine, shows that a simple test involving arginine vasopressin — or AVP — can reliably check whether a sick foal's hormone system is working properly. The finding could lead to quicker treatment and better survival rates for some of the most vulnerable patients in veterinary medicine.
Newborn foals face a hidden danger: their endocrine systems, which release hormones into the bloodstream, are not fully developed at birth. When a foal becomes ill, its body normally responds by flooding the system with hormones including ACTH, cortisol, and AVP — essentially calling in biological reinforcements to fight the illness. But if the hypothalamic-pituitary-adrenal gland axis, known as the HPAA, fails to respond properly, the foal's chances of survival drop sharply.
"The HPAA in particular is important for foal survival," said Katarzyna Dembek, an associate professor of equine medicine at NC State. "That's because when a foal is sick, it stimulates the HPAA to release a cocktail of hormones that help the body survive critical illnesses."
The current gold-standard test for checking this system uses a hormone called ACTH stimulation. But Dembek and her team suspected a different approach might work better for newborn foals. AVP stimulates ACTH release and happens to be the primary ACTH-releasing hormone in horses. The researchers wondered if giving a foal AVP and then tracking how its body responds could reveal whether its hormonal defenses were functioning.
The team studied 60 newborn foals, all less than one week old. Fifteen were healthy, 19 had sepsis, and 26 were sick but did not have sepsis. After administering AVP, researchers measured ACTH and cortisol levels in the blood at 15, 30, 60, and 90 minutes. They found that both hormone levels rose in all groups within 15 to 30 minutes. But septic foals showed weaker responses — their hormone levels were lower and did not climb as quickly.
This pattern could become a diagnostic tool. Foals whose hormone levels barely budged after the AVP test might be premature, even before obvious clinical signs appear. And recognizing HPAA dysfunction early opens the door to hydrocortisone therapy, giving these fragile patients a better shot at recovery.
"AVP is widely available, compatible with horses and largely affordable," Dembek said. "Its use in diagnosing HPAA dysfunction warrants further exploration." Dembek is also studying whether the same approach could help critically ill adult horses.
For foals and their owners, this research offers a concrete new option where few existed before.