On a long motorway journey while driving behind a horsebox, I wondered, do horses get travel sick? In fact, do we know whether any animals besides humans suffer from motion sickness?
鈥� Horses are unable to vomit, except in extreme circumstances, because of a tight muscle valve around the oesophagus. So it is difficult to know whether or not they feel sick. Other monogastric animals can vomit. Younger cats and dogs frequently vomit during their first car journeys but rapidly become accustomed to travel and no longer suffer sickness. In the UK a neurokinin-1 receptor antagonist has recently been licensed as a treatment for motion sickness in dogs as it reduces the urge to vomit.
James Hunt, Taunton, Somerset, UK
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鈥� Motion sickness is common among animals, affecting domestic animals of all kinds. A carsick dog is not only pathetic, but messy. In his unforgettable book, A Sailor鈥檚 Life, wrote: 鈥淢y worst memories of life at sea have to do with cattle. Two things no sailor will ever forget after such an experience are the pity and the smell鈥� cattle get seasick, and the rolling of the ship terrifies the wits out of them. A seasick monkey or pup may be amusing and easy to deal with, but five hundred head of cattle in the throes of seasickness are a nightmare鈥︹�� He also mentioned horses explicitly and even fish transported in unsuitable conditions may show signs of disorientation.
Motion sickness is ubiquitous because all vertebrates have organs of balance and they correlate balance with feedback from other senses to stay upright. When movement causes say, visual information to conflict with balance, the brain of a sensitive individual interprets the disorientation as a symptom of poisoning and a typical reaction is to vomit to clear the gut.
Jon Richfield, Somerset West, South Africa
鈥� Both Robert Falcon Scott and Ernest Shackleton took ponies with them to Antarctica. On the way they experienced some appalling weather, and both noted how badly affected their animals were. They did, however, perk up when the storms abated. Similarly, Scott鈥檚 dogs spent most of the storms curled up or howling, suggesting they too were suffering. Animals with a similar auditory system to ours would suffer from motion sickness, because it is caused by the confusion of auditory and visual inputs.
Tim Brignall, Bristol, UK