NOW that the international horses have arrived, some of the problems facing them are already apparent. Dermot Weld’s Melbourne Cup hope Galileo’s Choice fell ill soon after arriving. With any recently travelled horse the concern is they might have ”travel sickness”. If this is the case, the focus shifts from getting to the races to simply saving the horse’s life as it is an extremely serious condition and one which can be fatal if not treated early or if the horse does not respond.

So what is travel sickness and why are the international horses at risk? Travel sickness is the lay term for pleuropneumonia, an aggressive infection affecting the horses lungs and pleura (the lining of the chest cavity). In its most severe form, litres of fluid literally fill the lungs and the chest cavity, almost drowning the horse from within.

We used to believe that the horses who developed travel sickness were horses that already had an underlying problem such as a mild viral lung infection, which triggered pleuropneumonia when these horses were subjected to stress such as a long trip – hence the term ”travel sickness” was coined to describe the condition.

But while that still applies, we now know that this disease is multifactorial and many elements come into play – such as the duration of the flight, breaks or stopovers, access to food and water during the flight, how the horses are restrained during the flight, and a horse’s own individual ability to cope with stress. Racehorses that are travelling present as a vulnerable group – this is because the immune system in very fit, highly trained athletes seems to be marginal. We see this in human athletes that seem to be at greatest risk of getting sick when they are at the peak of fitness and performance.

The same applies to fit racehorses – their immune system and defence to infection is weakest when they are fit and racing. On top of this is the effect of stress. We know that stress causes the body to release cortisone from the adrenal gland and that cortisone further suppresses the immune system or the body’s defences – so a stressed, fit athlete is at greater risk.

How the horses are managed during the flight has surfaced as a crucial element. We now recognise that horses depend on ”gravity drainage” to help clear mucus and other contaminants from the airway. This means they need to be able to put their head down during the flight – so having them somewhat unrestrained, and feeding and watering them off the ground facilitates this ”gravity drainage”.

Interestingly, horses used to travel in a crate with a chest bar keeping the head up – but when the chest bars were removed, which allowed the horses to put their head down, the incidence of travel sickness dramatically reduced. Hydration is now recognised as a significant factor. This is because in a dehydrated horse, there is a drying effect to the lining of the lungs and windpipe. In a normal horse this lining is moist, which acts to trap or catch foreign matter – dust, viruses, etc, which are then passed up the windpipe and cleared by the horse.

Ensuring the horse is well hydrated before and during air travel is an important strategy in minimising travel sickness. It is common for horses to be treated with intravenous fluids before and after travel. IV fluids are used during a flight if there is a concern about a horse’s hydration.

The ventilation within the aircraft is another area that has improved in recent times, as clearly poor ventilation would increase a horse’s exposure to airborne pathogens. Not surprisingly, the length of the trip is another critical factor. It would appear that around 10 hours is the critical time, with trips longer than that producing a significant increase in the percentage of horses getting a temperature after the trip.

It is interesting to note that veterinarians in Hong Kong observed about 15 per cent more sick horses arriving in Hong Kong from New Zealand, compared with those from Australia. The travel times were 14 hours from New Zealand and nine hours from Australia. Horses coming to Australia from Europe generally have a three-leg trip, each of seven to nine hours in duration.

In Hong Kong at times there has been the hit-and-run approach, where horses don’t have to be quarantined for long periods, so they can fly in from Europe and race almost immediately. This is a successful approach as the jet-lag effects are delayed and avoided.

As well as all these extraneous factors, there is simply the fact that some horses cope with travel better than others – perhaps it is mental toughness.

These horses are probably less stressed and keep eating and drinking well throughout the trip, meaning they are better hydrated and don’t lose as much weight.

While travel sickness is a potentially serious disease, as with most diseases early recognition and early treatment generally produces excellent recovery. Although it can be an insidious disease one of the first signs is an elevated temperature, so the temperature is regularly monitored in horses during the flight and after arrival.

Even when the horses arrive in a healthy state, that is not the end of the problems. There are the nuances of quarantine, where the feed and water are different and sometimes unpalatable to the horses because they are different or altered by the sterilisation procedures applied to imported feed.

There are the difficulties associated with having a new veterinarian and farrier, who are unfamiliar with the horse’s problems, idiosyncrasies and the treatment/management strategies that have been used successfully in the horse’s home environment.

Finally, there are the problems we see with these overseas horses acclimatising to the different climate and track conditions. The European horses, in particular, are used to exercising and racing on lush grass tracks with plenty of give in the ground. Many struggle with the hard tracks that the Australian climate throws up, so bruised and sore feet are a common complaint. Similarly, many also have joint and bone problems that come with the need to gallop on surfaces that are different, harder and less forgiving than the tracks back home.

Dr Glenn Robertson-Smith is the founding partner of the Melbourne Equine Veterinary Group, one of the largest veterinary practices in Melbourne. He is a specialist in equine surgery and consults here and overseas.

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