Stallions housed in so-called social boxes had fewer undesirable social interactions when harnessed in pairs for carriage driving, fresh study findings show.
Researchers, writing in the journal Animals, said allowing horses to have more social interactions in their stables may have positive consequences on their behaviour during training.
“Previous studies reported increased aggressiveness between horses after social deprivation, especially during ridden training sessions, which could be explained by social frustration and an impairment in social skills induced by limited social contacts between horses,” wrote Annik Imogen Gmel and her fellow researchers at the Swiss National Stud Farm.
The authors said negative social interactions are of particular concern to equestrian disciplines using several horses simultaneously, such as carriage driving.
In this equestrian discipline, pairs are often chosen based on their affinity. “However, interactions between horses while driving can be dangerous for both horses and drivers, which is why horses are especially trained not to interact while they are hitched to a carriage in pairs.”
This is to ensure that the horses are attentive to the driver’s and the groom’s indications, and not to the other horse.
Indeed, the forcibly shared personal space could provoke the horses to seek interactions, in order to settle inter‐equine conflicts or to play, and ignore human instructions, which might lead to accidents.
Despite their training, interactions between horses still happen.
The study team set out to investigate whether housing stallions in social boxes changes their behaviour during carriage driving.
They hypothesised that the stay in social boxes would decrease the number of unwanted social interactions when driven in pairs.
Their work focused on eight Franches‐Montagnes breeding stallions, aged 4 to 14, owned by the national stud.
The horses were normally housed in individual boxes on straw litter and were fed hay and concentrate three times a day, with water available at all times. They were exercised 5 to 6 times a week.
During their initial training at 3 years old, all the stallions were ridden and driven to pass the Franches‐Montagnes stallion‐licensing test. However, after initial training, not all horses in the study were still driven regularly.
In the so-called “conventional boxes” at the stud, the partition between stalls consists of a lower solid wooden part standing 1.4m high, while the upper portion features closely spaced metal bars. This set-up allows visual contact and smells to cross, but strongly limits tactile contact.
In the so-called “social box”, the partition between two boxes consists of a portion with vertical metal bars from the ground to a height of 2.55m, spaced at 30cm. These allow the horses to pass their head, neck, and legs to the adjacent box.
The remaining part of the partition is solid, allowing the horses to visually isolate themselves from the neighbouring horse if they want. Each stallion has direct contact with only one neighbour.
Each set of two consecutive social boxes is then separated from the next set of social boxes by an opaque partition.
In the experiment, the eight breeding stallions were observed when driven in pairs with a “neutral” stallion housed in a conventional box that limits physical contact.
They were driven on a standardised route over a course on four different days before, during, and after being housed in social boxes.
The type and frequency of behaviours of the pairs and the interventions of the groom and the driver during the test drives were assessed live and using video recordings.
Analysis showed that unwanted social interactions decreased during and after the stallions were housed in the social box.
Stallions’ interactions also decreased over the four days, they noted, suggesting that they got used to the test conditions by learning not to interact, or by subtly settling dominance.
The social box tended to decrease unwanted social behaviours of stallions driven in pairs and could therefore be used as an environmental enrichment for horses, they concluded.
“Another important factor in reducing unwanted social interactions of stallions during carriage driving appears to be the consistency of the driver and the groom in their demands to teach the stallions that social interactions are unwanted while being driven in pairs,” the authors noted.
“Other effects, such as habituation to the test conditions and the pairing, could not be assessed here and represent a limitation of our study.”
The researchers said further studies should investigate if factors, such as the affinity between harnessed horses, could influence the number of interactions, and whether horses staying together in social boxes would show even fewer interactions when driven together.
The study team noted that single stable housing has been shown multiple times to be detrimental to the welfare of horses.
“This restrictive housing system offers poor opportunities for the horses to fulfill species‐specific behaviours, i.e., social interactions and locomotor behaviour, and results in animals staying in a frustration related stress state.”
Housing‐related welfare impairment can lead to undesirable traits, excessive aggressiveness towards humans, unresponsiveness towards their environment and an increase in alert posture.
It might also negatively affect the training of horses.
The study team comprised Gmel, Anja Zollinger, Christa Wyss, Iris Bachmann and Sabrina Briefer Freymond.
Gmel, A.I.; Zollinger, A.; Wyss, C.; Bachmann, I.; Briefer Freymond, S. Social Box: Influence of a New Housing System on the Social Interactions of Stallions When Driven in Pairs. Animals 2022, 12, 1077. https://doi.org/10.3390/ani12091077