Research

Published scientific studies confirm that extending daylength for mares using blue light from Equilume Light Masks advances reproductive activity as effectively as stable lighting, with the bonus that mares can be fitted with these masks while out at pasture, keeping mares in their natural environment. Early reproductive activity means production of early season foals and increases the economic value of youngstock. Light masks should be fitted 70 days before desired ovulations.

Research presented at the Equine Symposium of the British Society for Animal Science’s Conference, showed that pregnant mares wearing blue light masks in the final 100 days of gestation had shorter pregnancies, earlier post-foaling ovulations, developed larger follicles, and produced foals that were more mature at birth. The exciting studies, conducted by researchers at the University of Veterinary Medicine in Vienna, Austria, also found that foals from mares wearing light masks in the final months of pregnancy were 15 minutes faster at getting to their feet after birth than foals born to mares that did not receive additional light.

The two-year study was conducted at the historic Brandenburg State Stud in Germany. The blue-light stimulated mares developed larger follicles in the late stages of gestation and could be bred sooner after foaling. Foals born from mares wearing blue light masks also had shorter hair coats, demonstrating that the light perceived by the pregnant mare is transmitted to the foal and influences their physical development in utero.

These study findings show how correct light management of our pregnant mares can improve breeding efficiencies similar to Nature, but still allow foaling earlier in the year to fit with industry timelines.

Stallions too need adequate light duration for optimum fertility. While they can breed all year long, fertility is highest during the longest days of the year. Published studies have shown that semen volume, sperm concentration, libido and reproductive behaviour are all positively influenced by the duration of light. It is recommended that long-day light therapy for stallions also be initiated 70 days prior to the time of peak reproductive activity. This is especially important for young stallions facing their first breeding season when testes size naturally limits the amount of sperm that can be produced.

Research conducted by Equilume’s R&D team in conjunction with University College Dublin has revealed that time of year influences the response to extended daily light on coat growth in horses and ponies. The important practical take away findings from this research (O’Brien et al., 2020) can be summarised as follows:

• Horses and ponies have a strong seasonal rhythm and there are only certain times of the year when they are responsive to extended daylight
• Don’t leave it too late to start light therapy if you want to maintain a summer coat!
• For horses, ensure that lighting starts within one month after the summer solstice
• For ponies, it is advised to start light therapy at the summer solstice
• To induce early shedding of a winter coat, it is recommended that light therapy is initiated on or before the winter solstice
• The environmental temperature affects a horse or pony’s response to light therapy – ensure they are protected from the elements and well-blanketed
• Nutrition is very important and should be carefully monitored so that increased energy is provided to compensate for temperature drops
• Horses and ponies respond differently and may require different management depending on the rusticity of the breed

PPID Study 1: Impact of blue light therapy on plasma adrenocorticotropic hormone (ACTH) and hypertrichosis in horses with pituitary pars intermedia dysfunction

Pituitary Pars Intermedia Dysfunction (PPID) is a debilitating neurodegenerative disease of older horses. Affected horses frequently present with hypertrichosis (growth of a long curly hair coat that fails to shed properly) and suppressed immunity which leads to them suffering multiple infections, laminitis, lethargy and depression. Blue light therapy was proposed as a potential management tool for hypertrichosis and for investigating the impact of photoperiod manipulation on ACTH hormone profiles in these horses. In an initial preliminary study conducted at the University of Kentucky, PPID horses receiving blue light treatment via Equilume light masks had lighter hair weights compared to the PPID control horses. Results also suggested that while blue light therapy does not alter seasonal ACTH concentrations, it could be used as an additional management tool for hypertrichosis in PPID horses. 

PPID Study 2: Influence of Extended Photoperiod Using Blue Light Masks on Hypertrichosis, Coat Condition and General Health Parameters in Horses with Pituitary Pars Intermedia Dysfunction

In an intensive follow-up collaborative study between University College Dublin and the University of Kentucky, owners of 52 PPID horses were recruited from across North America and Europe and enrolled in a 12-month study using Equilume Light masks. The horses were divided into two groups. One group (29 horses) wore blue light masks from mid-December to extend their daylight exposure to 15 h daily. The other group (23 horses) acted as a control and experienced the natural changes in the light/dark cycle. As most (44/52) of these horses received daily medication to treat PPID, a second control group of unmedicated research horses (17 horses) was also recruited and experienced natural daylength changes for 13 months. Researchers measured hair length, hair shedding, and body condition monthly and collected owner feedback about other symptoms every two months. There was no difference in hair lengths between the blue-light-treated and the first control group, but the second control group had shorter hairs. Shedding started a month earlier in the spring for the blue light group. Owners reported better coat condition in April, less fat coverage in April and June, and more energy in February for the blue light group. A final survey showed improved coat condition, fewer PPID symptoms, and better quality of life in the blue light group only. These findings suggest that blue light masks can help manage PPID symptoms and work in tangent with pergolide to improve the health and well-being of horses with this condition.

Headshaking Syndrome: Effect of maintaining Equinox light on clinical signs of seasonal onset headshaking in horses: A preliminary study

Equine Headshaking Syndrome (HS) is a painful neuropathic condition that is believed to involve a seasonal, hormonally mediated alteration of the sensitivity of the trigeminal nerve, which runs down the side of the horses face, leading to overstimulation. HS affects geldings disproportionately and failure of negative feedback on seasonal hormone release by testicular testosterone has been hypothesized as a cause. The present preliminary study aimed to block the seasonal photoperiodic signal and test a light therapy treatment that maintained exposure to the same daylength from autumn through to spring. Owners of HS geldings with spring/summer clinical sign onset were recruited via an online survey in Australia. Horses were fitted with Equilume™ light masks providing 15 hours of light (08:00 – 23:00) for six months starting from the autumn equinox. Questionnaires were circulated to collect information on HS clinical signs and intensity at the start, middle and end of the study period. Clinical sign intensity was assessed on a 5-point scale: Not observed = 0; Very occasionally (i.e. observed once per week) = 1; Sometimes (i.e. observed several times per week) = 3; Often (observed at least once per day) = 4; Constantly = 5 (observed multiple times per day). Complete data from 10 participants was used for analysis. There was a significant reduction in the number of clinical signs reported over time (P<0.05). While not statistically significant, the reported intensity of each clinical sign reduced over time. Overall clinical sign intensity was reported as decreased by 7/10 participants, of which two reported complete cessation of headshaking behaviour. Quality of life was reported as increased by 6/10 participants. Results suggest that blue light treatment used to ablate perception of the shorter winter daylengths may offer a treatment option for managing headshaking clinical signs and justify future studies that incorporate improved methods to quantitatively assess HS intensity, blinding of reporters and increased sample size.

All mammals have an internal timing system that is responsible for regulating most aspects of physiology and behaviour. This internal timing system, or body clock, is regulated by the daily 24 h rhythms in light and dark exposure and functions in almost every tissue and organ. Domesticated species such as horses are often stabled and exposed to lighting at different times than they would in nature. The cells in hair follicles possess a clock that can be evaluated without the need for more invasive tissue collection. This study aimed to evaluate the clock in hair follicles of horses kept under two lighting systems. After 20 weeks housed with either an incandescent light bulb or a custom-designed LED lighting system, 24 h clock gene rhythms from hair follicles of horses housed under the LED lighting system were found to be stronger. The LED lighting system contained blue light by day, which is more like the light produced by the sun and is known to be responsible for keeping the biological clock ticking, and dim red light at night to help avoid the disruption caused by turning on a white light in the stables at night. Therefore, our results suggest that there is the potential to improve stable lighting for horses to optimise the function of the body clock and ultimately the health of horses. By improving the circadian (24 h) rhythm of horses, all aspects of their physiology can work in better harmony and in synchrony with the environment.