Health Problems of Young Horses in Training
Young horses in training are vulnerable to a wide variety of problems–everything from respiratory disease to training injuries. These horses are often taken off the farm where they grew up, transported to training facilities where they
Young horses in training are vulnerable to a wide variety of problems–everything from respiratory disease to training injuries. These horses are often taken off the farm where they grew up, transported to training facilities where they experience a new environment, and exposed to other horses from various places. This commingling of youngsters means they face diseases or strains of diseases they have not encountered before. Stress can hinder the immune system and make them more vulnerable to these infectious/ contagious diseases. Training for athletic performance can sometimes overstress immature bones, joints, tendons, and ligaments.
In this article we’ll take a look at problems faced by young horses when they enter training, and we’ll present information that could help your young horses stay healthier during this process.
Respiratory Diseases
Probably the diseases most common to young horses in training involve the respiratory system. Young horses have not encountered as many pathogens in their environment as older horses, so when they are taken from home pastures and exposed to other horses, they are vulnerable.
M.C. Baker, DVM, an equine practitioner in Weatherford, Texas, often sees respiratory problems in 2-year-olds in training. “Often we see pharyngeal folliculitis–blisters in the back of the throat,” he says. “This is generally associated with some kind of infection in the guttural pouch (the horse has one on each side of the oral cavity), often caused by Streptococcus. It may be either S. equi or S. zooepidemicus.
“This seems to be the most common respiratory condition in young horses,” he continues. “The blisters are lymphatic tissue, similar to tonsils in a human. It’s mainly just a troublesome irritation. If it’s due to Strep infection that’s contaminated the guttural pouch, the horse has chronic drainage from the pouch, which, in turn, causes chronic irritation in the back part of the throat. This results in prominent blisters and may develop into tracheitis (inflammation of the trachea) or bronchitis. The horse coughs and has a nasal discharge.”
This discharge is what horsemen often call the “snots” in young horses.
“A lot of these horses don’t cough unless they exercise,” Baker explains. “Then the guttural pouch starts to drain. Often a horse is set up for this condition by (rhinopneumonitis or EHV-1) or flu virus. The virus hinders the immune system, erodes the mucous membranes, and allows environmental bacteria (such as Streptococcus) to invade.”
Diagnosis involves taking blood and performing a blood count along with observing clinical signs.
“We also use a video endoscope to examine the guttural pouch as well as the trachea to see if there is any material coming up out of the trachea–pus or phlegm,” Baker says. “When there’s a lot of inflammation in the back part of the throat, it changes the integrity of the soft palate as well as the laryngeal area, just like a person with a really sore throat. It’s harder for the horse to swallow, so more debris accumulates back there.” The reason horses cough is to clear the debris.
A tracheal wash can help the veterinarian diagnose the problem. This involves flushing sterile water into the trachea and recovering the water with debris washed from the throat. A sample is cultured to determine the causative bacteria and what antibiotic works against it most effectively.
“Even though we have vaccines for flu and rhino, and for Strep, these vaccines may not hold, depending on how virulent the bacteria or the particular virus is and the amount of exposure the horse has,” says Baker. “These young horses are exposed to a lot of things, just like young kids going to kindergarten. They always come home with the snots.”
The California Horse Racing Board’s equine medical director Rick Arthur, DVM, says a major risk today is equine herpesvirus.
“At least 50% of horses have latent infection with herpes, whether or not they show signs,” explains Arthur. “There’s also significant risk for influenza, which is a much more aggressive viral infection than rhinopneumonitis. Flu spreads very quickly, just like it does in people, and it can be difficult to control.”
Fortunately, vaccines for influenza are much more effective than vaccines for equine herpesvirus.
“The new intranasal (flu) vaccines work very well; it’s a big advantage to have horses vaccinated,” says Arthur. “This doesn’t mean they won’t get influenza, but it definitely does inhibit spread of the disease. And if horses do get sick with flu, it tends to be a much less serious infection. They get over it faster and don’t get as sick.”
Most training facilities do a good job with sanitation, but many infections are spread via sharing of tack, bits, buckets, watering systems, etc., says Baker.
“These horses are coming from all over the country,” he explains. “The strain your horse is vaccinated for may not be the same strain being brought in. The young horse is continually exposed to a lot of different strains.”
“The horses also contend with bedding dust, irritants, and molds in the hay and environment,” Baker says. “These are all irritating to the respiratory system.”
Some facilities keep barns closed up tight, and the lack of ventilation can result in higher levels of ammonia, which might be irritating to the respiratory system and predispose a horse to infection. Anytime the tissues of the respiratory system are irritated, it is easier for pathogens to cause disease.
Vaccinations
Because these horses will be exposed to so many things when they are shipped off for training, they should have a good vaccination program in place before leaving home. “If you’re sending a horse off to a training facility, you certainly don’t want him to miss training days being sick,” says Baker. “It’s costly to miss days, and the horse also gets behind in his training schedule. Young horses (that have been primed with their initial vaccines) need to be vaccinated for flu and rhino at least three times, 60 days apart, before they go to the trainer and are subjected to these diseases.”
Arthur says with most vaccines it takes at least two vaccinations to start building immunity, after which a horse should be boosted at regular intervals. “In my practice, in horses in intense training, we vaccinated them as often as every 60 to 90 days for influenza,” says Arthur, who works with Thoroughbreds. “Most well-run barns pay close attention to vaccination schedules and try to give flu vaccinations at least four times a year and equine herpesvirus twice a year.”
Baker advises giving the Strep vaccine frequently. “It’s not a very protective vaccine, because it doesn’t cause a good antigen response,” he explains. “But it may give the horse more immunity.”
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