The impacts of transport on a horse’s well-being

There are 5 fundamental needs necessary for an animal’s well-being :
•    Absence of hunger or thirst ;
•    Absence of fear or distress ;
•    Absence of physical and thermal stress ;
•    Absence of pain, injury or illness ;
•    The possibility for the animal to express the behaviour considered normal for the species.

During transport, the conditions are specific due to :
•    Confinement ;
•    Lack of food or water;
•    The movements of the vehicle ;
•    Noise ;
•    Road conditions and the way the vehicle is driven ;
•    Separation from a familiar environment in addition to either isolation; or inappropriate groups ;
•    Temperature and climatic and environmental conditions;
•    Humidity in the vehicle itself.
The horse’s well-being can no longer be respected. Certain behaviour and parameters contribute to establishing this fact.

Muscular fatigue

One  could suppose that this position compensates for the movements of the vehicle and gives the horse more stability. However this posture requires a constant muscular effort from the horse, therefore increasing his energy expenditure and muscular fatigue (Waran and Cuddeford, 1995). The horse’s performance in a competition partly depends on his energy metabolism and stored energy, factors which may be disrupted by transport (Fazio et al.,2008).

Abnormal behaviour

When we compare a 50km trip and a 200km trip, the shorter journey causes proportionally more stress than the longer journey. This could be due to a lack of time for the horse to adapt to a new situation.
Some horses will be particularly stressed by a transport situation, and can appear aggressive, neighing and pawing. Horse will also sometimes try to turn round,  and end up with their neck bent backwards, and their head stuck between the partition of the vehicle and their flank. Some horses will demonstrte stereotypical behaviour, such as crib-biting, triggered by a transport situation.

Perception

A horse’s eyesight is very sensitive to movement and contrast compared to human eyesight. Areas of light and darkness in the vehicle can therefore be disturbing for a novice horse. In addition, the horse’s eye accomodates slowly when there is a change in light intensity. This explains that horses will often slow down or stop for a moment when loading from the ramp to the vehicle which is darker. Providing educaton for loading will alleviate this, and ensure that transport situations go smoothly subsequently.

The horse can also be disturbed by noises in the environment (engines, partitions in the lorry…). The horse’s frequency range is  55 to 33500 Hertz, so he peerceive the sounds that we hear, but can also hear ultrasounds.

Heart rate

During transport, and even more when loading, which is considered to be the most stressful moment of a journey (Schmidt et al., 2010), the horse’s heart rate increases. Even more so when loading a young inexperienced horse.
Even with education, the horse’s heart rate will be higher during transport, than when resting. In fact, even if stress can decrease thanks to a learning process, the muscular effort required during transport will contribute to increasing the horse’s heart rate.

Cortisol rate

Cortisol is a hormone secreted by the adrenal gland from cholesterol. It is commonly known as the « stress hormone » and uses the body’s reserves to deal with stress, warning the organism of a « dangerous » situation.
With horses cortisol levels in saliva have been observed to increase substantially when loading. The level decreases again during travel, but remains high compared to rest levels. Once the horse is used to travelling, cortisol levels increase a lot less. The level goes back down to normal quite quickly a few minutes following unloading (Schmidt et al., 2010).
When cortisol levels remain high  for a prolonged period, they can decrease the progesterone level in gestating mares, causing them to abort. During transport, the abortion rate increases, but mostly over long periods of transport rarely in journeys of under 8 hours (Baucus et al., 1990).

Dehydration and weight loss

During transport horses seldom have constant access to water. This can lead to dehydration following a journey. A horse may lose between 0,45 to 0,55 % of his body mass per hour due to losing body fluids (breathing and sweating). This means that a horse weighing 500 kg can lose up to 30kg during a 12 hour trip. This weight loss is however regained over a 3 to 7 day period following the trip (Leadon, 2000).
When travelling for 24 hours, a horse could therefore lose up to 6 % of his body mass : this is why it is important to give him access to water at regular intervals.