Head gear is all the rage for our horses these days. We’ve got fly masks, nose nets and ear guards – and now we could see brood mares donning a natty new light mask.

Artificial light

Artificial light has long been used in breeding circles to extend a mare’s reproductive cycle. In the natural world a mare would give birth during the longest days of summer (ie between May and September), which gives their foal a stronger chance of surviving.

However, in the racing world foals are normally born around 1 January, in order to produce mature yearlings and two-year-old racehorses. This is where light therapy comes in.

“Mares are maintained indoors under barn lighting until 11pm for eight to 10 weeks beginning around 1 December,” explained Dr Barbara Murphy, a lecturer in equine science with the school of agriculture and food science at University College in Dublin. “The artificially extended day length acts to inhibit the hormone melatonin and fools the mare’s reproductive system into activating earlier in the year.”

Advance breeding season

Research showed that the inhibition of melatonin didn’t differ whether light was administered to one or both eyes. A second study in Kentucky was then carried out to see if a light mask, which shone low-level light into one eye, could bring forward the breeding season in mares that lived out.

Fifty-nine Thoroughbred mares were used in the test carried out in December, and divided into three groups. Group one lived indoors under barn lighting until 11:00 pm every day; group two wore light masks programmed to be on from 4:30 pm to 11:00 pm daily and lived outdoors as a herd; and group three lived outdoors under the natural light, as a control.

Two months later the number of mares found to have ovulated was 87.5% in group one; 80% in group two; and 21%, in group three. This shows that indicating that mobile light therapy is as effective at advancing the breeding season as indoor lighting.

The Equilume light-mask will be available commercially from 2013.