Serum thyroxine and triiodothyronine concentrations in neonatal foals and mature horses.

This study investigated the levels of two types of thyroid hormones in newborn foals andadult horses. It found that foals had higher concentrations of these hormones than adults, with potential implications for the normal growth and function of their nervous and muscular systems.

Research method and subjects

• The research focused on the concentrations of two thyroid hormones, thyroxine (T-4) and triiodothyronine (T-3), in the blood serum of newborn foals and adult horses.
• The scientists used a modified radioimmunoassay procedure to measure the concentrations of these hormones.
• Blood samples were collected from 52 clinically healthy foals and horses. The sample set included various breeds including Thoroughbreds, Quarter Horses, American Saddle Horses, and a single cross-bred horse.

Key findings

• The study found that newborn foals had high concentrations of T-4 and T-3 in their blood, compared to adult horses.
• There were no significant differences in T-4 concentrations between different breeds and sexes. However, stallions were found to have slightly higher T-3 concentrations.

Significance and implications of the findings

• The researchers suggested that the higher levels of T-4 and T-3 in foals could play an important role in the normal functioning of their nervous and muscular systems.
• They drew parallels with human health, noting that hypothyroidism in equine neonates has reported signs similar to those of prematurity in people, such as neuromuscular incompetence and musculoskeletal dystrophy.
• Therefore, measuring T-4 and T-3 levels in newborn foals could potentially be a useful screening test for hypothyroidism, a condition in which the thyroid gland doesn’t produce enough thyroid hormones.