Why the long face?

A new study has revealed that horses may suffer from a form of Seasonal Affective Disorder, a type of depression that effects humans during the winter.

SAD is caused by a biochemical imbalance in the brain due to fewer daylight hours and a lack of sunlight.

As well as feelings of depression, it can cause sleep problems, lethargy, overeating, anxiety and mood changes.

Now it appears that horses are not immune to winter blues either.

Treatments for humans with SAD has traditionally involved light therapy which is successful in 75 per cent of cases. It involves daily exposure to a special light box at least ten times the intensity of ordinary domestic lighting for a period of one to four hours.

A link between horses and humans was not made until a producer of light boxes approached Nottingham Trent University wishing to establish whether its products would be successful on equine patients.

"The company produced the boxes for human treatment," explained Carol Hall, senior lecturer in equine sports science at the university and a specialist tutor of equine psychology with a particular interest in horse behaviour and welfare.

"Someone working for Brite Box was involved with horses and knew they could get grumpy in the winter so the company approached us with regard to researching a possible link to SAD in horses."

The team at NTU looked at the behaviour of a group of horses, half of which were given light treatment therapy by standing under specially designed light strips for an hour a day for six weeks.

The other six were treated as normal.

Horses are often kept stabled during the winter and consequently live for long periods in unnaturally dark conditions.

Those taking part in the study were assessed on various aspects of their behaviour before and after the light treatment therapy.

Their sleep and eating patterns were monitored and they were scored on how they reacted to being handled and to being isolated from other horses, as well as how they performed when being ridden and jumped.

Every attempt was made to ensure a fair test with a mixture of breeds and sexes and with six similar pairs of horses chosen, one in the control group and one undergoing light therapy.

All horses were selected for their even temperament and were in full health

The results were recorded by students who did not know which horses had been exposed to light therapy and they showed a difference between the two groups.

Although those that had undergone light treatment therapy did not show much of a change in any of the behaviour that was tested, those that had not stood under the lights showed some sign of suffering from the winter blues.

They slept for slightly longer than they had previously and were less enthusiastic about being ridden as demonstrated by poorer performance when jumping.

Those that had undergone the light therapy were reported by the yard manager as being less grumpy than they usually were at that time of the year.

Carol is reluctant to make any generalisations on the findings though.

"We couldn't be sure that these results were as the result of SAD. They could just as easily be due to other seasonal factors," she said.

"Horses could be negatively affected by the lack of light due to increased stabling but it's just as likely that this is due to the associated problems of lack of equine company and claustrophobia."

Carol says it is difficult to predict which horses might be affected by lack of daylight.

"As with people, some horses may be affected more than others. This is not a general condition affecting all horses. It also doesn't appear to be related to hormones or biological sex. Of the horses studied, the two who showed the most grumpiness were both geldings."

She said it was vital that horseowners didn't attribute unexplained grumpiness or changes in their horse's behaviour to SAD.

"If you are at all worried about your horse you should always contact your vet as the symptoms shown might be nothing to do with SAD," said Carol.

The team is embarking on further research, this time using Actulite lights which use a polarised natural light system.

The lights are left on all day but their spectral radiance was more akin to daylight, Carol explained.

"The research shows what we all know to be true - that for the vast majority of healthy horses, exposure to daylight is essential and turnout is the best method of providing this.

"People are more aware now of the problems involved with keeping horses stabled and how over stabling can be detrimental to their welfare," said Carol.

"In practical terms, our results point towards the best idea being horses living as natural a lifestyle as practical with other equine company.

"Quite small things can make a difference to horse's behaviour so it is up to us to consider the features that might affect our horses as individuals."