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Study Indicates High Insulin Sensitivity In Newborn Foals, Challenging Existing Research

Though longstanding literature suggests that newborn foals have impaired glucose tolerance due to immaturity of their endocrine system, scientists at Ohio State University recently determined that newborn foals are actually more sensitive to insulin than mature horses.

Led by Dr. Hannah Kinsella, the team evaluated glucose and insulin levels in healthy newborn foals and compared them to the levels of healthy horses using intravenous glucose tolerance test samples. Twelve healthy Standardbred foals between 24 and 60 hours old were used in the study; eight horses of other breeds that were between 3 and 14 years were also used.

The results suggest that a newborn foals' pancreas can secrete a high level of insulin, which allows it to save energy. Baseline glucose in foals was found to be significantly higher than in horses, showing that foals are insulin sensitive in their first days of life.

The ability to maintain normal glucose levels may also prevent low blood sugar right after birth. The team suggested that this may indicate evolutionary adaptations that allow the foal to transition to life outside the womb.

“Published reference ranges for glucose in the neonatal foal are higher than those used for adults, and the results of this study further solidify that this should be taken into account in the clinical management of the neonatal foal,” Dr. Kinsella reported. “The question of whether the use of tight or liberal glycemic control is more beneficial in the treatment of the critically ill neonate continues to remain controversial, and additional investigation is warranted.”

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Read the study here.

Diet And Exercise Key To Managing Tying Up From PSSM

Polysaccharide storage myopathy (PSSM) is a glycogen storage disorder in horses that causes muscles to cramp. It occurs primarily in horses with Quarter Horse bloodlines, like Paints and Appaloosas, but it can also occur in draft horses, draft crosses and Warmbloods.

In normal horses, insulin goes from the blood and is stored as glycogen in the muscle and liver cells. In horses affected by PSSM, a large amount of sugar (glycogen) is stored in the muscle and up to four times the typical amount of polysaccharide (an abnormal form of sugar) accumulates in the muscles.

Horses with PSSM are generally in good weight and have a quiet temperament. They often experience a PSSM episode when they begin training or go back into training after a layup, when their movement is restricted. The episode normally comes on after the horse has been walking and trotting for about 20 minutes.

When a horse has a PSSM episode, their muscles get very stiff and hard, especially over their hindquarters; they will sweat profusely, refuse to move, and their flanks may tremble. When they stop moving, the horse may stretch out as if urinating. Foals with PSSM often show signs of muscle pain and weakness when they have diarrhea or an infection like pneumonia.

Horses that have PSSM should not be fed sweet feed, wheat, oats, barley, molasses or feeds high in starch. They should also be exercised daily. Exercise encourages the body to use glucose properly and improves energy metabolism in skeletal muscle.

Researchers have found that if horses have only their diet adjusted, about 50 percent will improve. If both diet and exercise are adjusted, more than 75 percent of horses with PSSM will have few or no tying-up episodes. Though it may seem counter-intuitive, horses should be turned out and encouraged to move as soon as a PSSM episode has dissipated.

Confirmed: Specific Patterns Of Fat Associated With Laminitis, Similar To Human Obesity Issues

Though horse owners and equine veterinarians have long believed a cresty neck to be associated with equine metabolic syndrome and associated laminitis, there has never been scientific proof of the link—until now: New research out of Australia has confirmed the correlation, reports EQUUS magazine.

Fat tissue stores energy and plays an important role in the synthesis and release of hormones that assist with metabolism and insulin function. Abnormal insulin function is a key risk factor for horses that develop hormone-related laminitis.

Drs. Danielle Fitzgerald, Stephen Anderson, Martin Sillence and Melody de Laat used 26 ponies for a study to determine if there is a correlation between cresty necks and the incidence of horses developing equine metabolic syndrome. Each of the ponies was given a body condition score (BCS) and a cresty neck score (CNS), which objectively measures the accumulation of fat on the neck. The scale goes from 0 to 5, with 5 indicating that the crest is so large it had dropped permanently to one side.

The ponies were then divided into three groups: those with a CNS of 3 or greater, but moderate body condition; those with a CNS of 3 or greater that were obese; and those that had moderate body condition and no cresty neck. The researchers used an oral glucose test to determine how each pony regulated insulin.

From the results, the scientists concluded that crestiness was a primary indicator of insulin dysregulation. Ponies that were not overweight, but that had a cresty neck score of greater than 3, were five times more likely than non-cresty neck ponies to have insulin dysfunction, and therefore be at risk of laminitis. Obese horse without a cresty neck were less likely to have an increased risk of insulin dysregulation and related problems.

These finding confirm what horse owners and veterinarians have suspected, that a cresty neck is a key indicator that a horse or pony has an insulin regulation issue. The results are also consistent with human obesity studies that link specific fat accumulation patterns to health complications.