Here is a quick look at some of the research on floating:
This recent article from Equine Science Update found that horses prefer to travel backwards in larger bays. It found that travelling induced or exacerbated stomach ulcers in horses, and recommended that you feed your horse right up until the time of departure.
This article talks about the positives and negatives of straight versus angle loading. It points to a study from Kentucky Equine Research that allowed horses to travel loose in a box. Apparently some horses preferred to travel facing fowards, some facing the rear, but none chose to travel sideways. The author says that the research claims that horses able to lower their heads suffer less respiratory stress.
Interestingly, I have searched for this research and have been unable to find the original source.
This study from The Journal of Animal Science said that horses able to raise and lower their heads, and move their feet had better balance. Here is the abstract:
A review of recent research on the transportation of horses
Journal of Animal Science, Volume 79, Issue suppl_E, 2001, Pages E32–E40,
Horses are transported more frequently than any other type of livestock. Most of our understanding about horse transport has been based on custom and conjecture, but some recent studies have greatly increased our knowledge. Although some horses adapt to transport much better than others, transport is generally associated with lower reproductive rates, increased disease incidence, a temporary reduction in athletic performance, and the alteration of many other physiological traits that are indicative of stress. Horses show marked dehydration after 24 h and extreme dehydration after 28 h of transport in hot and humid conditions when there is little nighttime cooling. Watering horses onboard trailers alleviates dehydration, but fatigue can become extreme after 28 h of transport. Orientation either toward or away or diagonally from the direction of travel does not seem to significantly affect a horse's ability to maintain its balance. Allowing horses the ability to raise and lower their heads or hind quarters and to take at least one step in any direction seems to be the most important factor in their compensating for changes in inertial forces.
This article then talks about horses transported in groups. In short, they experience more stress and more injuries than horses in separate bays.
Here are some tips on maintaining your horse's health during transport:
1. Accustom your horse to loading calmly well before you plan to travel
2. Keep your float clean so there is no ammonia smell
3. Make sure you hay is not dusty which can effect lung health
4. Allow your horse to feed right up until the time of departure, so their stomach is full which helps with reducing the symptoms of stomach ulcers
5. Offer water whenever possible, as horses frequently dehydrate during travel
If you float regularly and would like to support your horse's gut health, Sound Advice has two products that are very useful - both by Alltech Lienert. Bio Mos and Yea Sacc - a prebiotic and a probiotic - both are yeast cultures. Both have a dosage of 10g per day making them very cost effective.
Sound Advice Calm Mix is a muscle relaxant, so it can help with stiffness and soreness horses experience when they are essentially "surfing" - maintaining their balance in a horse float.
Horses find travelling stressful - even if they do it regularly. Allow your horse to recover after travelling. Allow yourself to recover too!