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MANAGEMENT An unhappy traveler Q:
My 15-year-old mare is a veteran show horse. She performs well and always seems relaxed and happy when I load her for the return trips. However, twice in the past year she arrived home looking uncomfortable. Both times, I called my veterinarian, who diagnosed a mild colic and gave her a dose of Banamine.
She recovered fully within a few hours each time. But I am hesitant to put her on a trailer again. Can transport alone cause colic? What might be going on?
Name withheld upon request
A:
This is a really important topic. Most cases of colic are caused by changes in feed, water or management, including work schedules, turnout times and types of pasture. What many people don’t realize is that transport can be considered a management change.
Trailering per se is not the problem; rather it is the change in what a horse “goes through” that affects the gut. It’s a little bit like if you had to go to a job interview at a location you’ve never been to before---you’d experience a heightened stress response. This is similar to what happens to a horse in a trailer ---under stress, his brain signals for certain physiological changes in his body, which in turn affect gut motility and the quantity of water and nutrients absorbed. For your mare, these physiological changes are enough to induce the mild digestive upset you’ve seen.
To reduce or prevent this problem, I would start by looking at the first two types of change that can bring on colic: food and water. When traveling with your horse, take steps to keep her eat-
ing and drinking on as normal a schedule as possible. This may mean making hay available at all times in the trailer and encouraging your horse to eat and drink at the show. I would focus on water and hay, rather than grain, on the day of transport to maximize gut movement and encourage a healthy microbiome (gut microbial population).
For racehorses and others routinely hauled over long distances, it is common to have a veterinarian check the horse before the trip and to administer a laxative proactively to keep the gut contents moving while his diet and water intake are fluctuating. That might be something to consider if your mare’s bouts with colic become chronic.
It is also possible that your mare finds trailering particularly stressful. Had you made any changes prior to her first bout of travel-related colic? Even something as seemingly benign as new tires or a new tow vehicle may be giving her a rougher ride. Many horses also have distinct preferences for how they travel: Some are more comfortable in a partitioned trailer with a companion, while others are more relaxed in an open stock trailer, where they can move around. Simple changes like leaving the lights on inside the trailer and letting a horse see out a window can ease anxieties. Also think about your driving: A steady, smooth ride will be easier on horses than one with too many abrupt stops and fast turns. You know your horse, so you are the best judge of which strategies may help her.
Another thing to consider is that
some horses may develop stomach ulcers in response to the stress of trailering. Ideally, you would have your veterinarian do an endoscopic exam on your mare to see what her stomach looks like so that you know what you are treating or preventing. But many horses do well when they are proactively put on omeprazole (GastroGard) beginning about three days before transport.
You might also investigate supplements formulated to support the microbiome and reduce ulceration. It might take some trial and error to determine what works best for your mare. I don’t want anyone to think there is a “magical” product that will resolve the problem you are seeing, but there are some sensible supplements that will help support gut health by adding microbes and stomach buffers.
I strongly suggest you ask your veterinarian how to manage this situation. He or she knows more about your mare’s history and will likely have some other ideas that may help her. Anthony Blikslager, DVM,
PhD, DACVS North Carolina State University Raleigh, North Carolina
Q:
My 15-year-old Tennessee Walking Horse mare coughs three or four times at the start of every ride, usually just after we pick up a trot. It happens whether we are in the indoor or outdoor arena or on the trail. She doesn’t have a history of respiratory problems and she doesn’t seem to have trouble breathing. Should I be concerned?
Name withheld upon request
A:
Coughing is a reflex triggered by stimulation of receptors (cells sensitive to external stimuli) located between the larynx (throat) and deep lung. When material in the horse’s airways comes into contact with these receptors, nerves are stimulated, which trigger a cough. This is a protective reflex to clear out mucus and inhaled dust par- ticles from the airways and prevent the horse from drawing foreign substances into his lungs.
In some horses, however, the receptors become over-sensitized, typically when the airways have been irritated by inflammation (for example, after a viral or bacterial infection) or an allergic disease (such as equine asthma). Once irritation occurs even relatively minor aggravation triggers a cough. Exercise is likely to trigger coughing because the rapid movement of air in and out of the lungs may mobilize excess mucus.
Given that your mare has not been sick and her intermittent coughing has been present for at least a month with no evidence of difficulty breathing, I suspect that she has an allergic lung disease such as mild equine asthma ---this is the current term for inflammatory airway disease (IAD), which is a milder form of recurrent airway obstruction (RAO), also called “heaves.”
A horse with mild asthma will seem normal while resting but will cough when exercised. The condition is usually triggered by exposure to dust. Some horses are more susceptible than others to given dust levels.
The best way to confirm a presumptive diagnosis of equine asthma is to have your veterinarian examine the mare and perform a bronchoalveolar lavage (“lung wash”). Done under sedation, this test entails the insertion of a long, sterile tube through the nostril, down the windpipe (trachea) and into the lung. Then the veterinarian injects a sterile saline solution to “wash” a small region of the lung lobe and draws the fluid back out immediately.
The fluid recovered---a mixture of mucus, cells and saline solution---is then analyzed at a laboratory. Examination of the cells under a microscope will determine if the lung is inflamed.
Management of equine asthma starts with strict control of dust in the
horse’s environment. The most common sources of dust exposure are feed and bedding---hay and straw in particular are associated with high amounts of dust in the air, especially if the hay is fed from a net or rack.
Cleaning stalls and alleyways in the barn also generates high dust levels that take approximately one hour to settle down. The best living situation for horses with mild asthma is turnout for extended periods.
Your veterinarian is in the best position to suggest strategies to reduce your mare’s exposure to dust. General recommendations might be to replace hay with complete pelleted feed or soaked hay cubes as well as to switch her bedding from straw to wood chips or other low-dust options.
Arena footing may also generate high levels of airborne dust. Sand arenas become increasingly dusty over time as the particles break down with repeated use. Sprinkling water on the surface helps, but the effects may be short-lived, especially in drier climates. You might also investigate replacing your arena footing with a low-dust synthetic option.
Feeding a supplement rich in omega-3 fatty acids will further help speed up your horse’s recovery, especially when this is done in concert with measures to reduce her exposure to dust. If her coughing does not subside after implementing dust-control mea- sures, or if you need her to return to her regular activities promptly, treatment with inhaled corticosteroids and bronchodilators will help.
It is essential to have your veterinarian make the diagnosis and then discuss the measures most appropriate for your situation. Laurent L. Couëtil, DVM, PhD, DACVIM Purdue University West Lafayette, Indiana