Monday, February 27, 2012

Scoliosis in Adult Equines

Scoliosis in Adult Equines

Q: I purchased my Thoroughbred gelding when he was 5 years old. Within the next two years we were doing really well at entry level dressage. He looked and behaved fantastically.
Then the problems started. As I ride on my own and hadn't had this problem before, it took me a while to figure out that his refusing to go (forward), bucking, and general naughtiness was not disobedience at all, but serious pain from a saddle that was a bad fit. It seemed to be blocking his shoulder movement and extending the pain right through to his hindquarters.
We trekked five hours down to Johannesburg for a new, properly fitted saddle, X rays of his spine, and physiotherapy.
I changed his routine completely from mainly arena work to mainly trail riding, and I just didn't feel he was getting much better. It was on my fifth saddle fitting with the same qualified saddle-fitter that she noticed his spine is skewed to the left.
Do you think that through some imbalance in my posture I caused this crookedness in his spine? Could it be caused by overschooling with pain and incorrect muscle use? Or do you think that the scoliosis was always there and that it has just become worse over the years?
He is on lysine (an amino acid critical for growth as well as muscle and tissue development) and a joint supplement. His teeth are done regularly, and his feet are good (I went so far as to check his angles and breakover with the American Farrier's Association through sending pictures).
Can scoliosis be corrected with work and stronger muscles to support the spine?
Natasha van der Walt, Louis Trichardt, South Africa

A: Scoliosis is a (pathological) condition of the spine where there is a kind of S-shaped deformation of the spine in the lateral plane. That means the spine is not straight as it is supposed to be from head to tail, but has an S shape (like a snake) in the spine to the left and right, in most cases in the chest or loin region.
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Scoliosis usually is a developmental condition occurring after birth. During the growth period of the young horse there might be imbalances (due to feed/work/injury/genetics, etc.) causing spinal deformation, resulting in deformation of the bony structures. This situation is permanent, and it will limit the horse in his normal mobility of the spine. Depending on the kind of work the horse is doing, this could be a problem. You can imagine that for trail riding the horse does not need a lot of flexibility to the sides in its spine, while in jumping or dressage this can clearly be a limitation. With time the scoliosis can become more prominent due to adaptations of the spine due to loading. Also muscles might become atrophied and the spinal curvature could become more pronounced. Realize that when scoliosis is more chronic, quite often the abnormal shape of the spine will limit the flexibility, but the process is not particularly painful.
Scoliosis also can be an acquired condition developing later in life. Injury to the certain spinal structures (intervertebral disk, facet joint, vertebral body fracture) causes parts of the spine to be painful or nonfunctional. Due to pain the muscles around the spine try to protect the affected area and contract (spasm). When this situation goes for a long period of time, the shape of the spine can be altered and develop the same S shape known as scoliosis. This type of scoliosis has the tendency to get worse with time, especially when the originating cause is not treated. Also, when the originating cause is not treated, quite often the horse will experience pain.
In the developmental condition there is not a lot we can do to influence the outcome. However, when the scoliosis is acquired, especially if caught in an early stage, dealing with the originating injury might stop the process of deformation of the spine. Rehabilitation with specific exercises can assist in treating the primary injury, as well as dealing with the acquired S shape, and they can make the horse more comfortable and less crooked. A correct diagnosis is a first step in this process, and a complete physical exam, followed by diagnostic procedures, such as scintigraphy (bone scan), X rays, and ultrasonography, should be performed, but I am not sure if these modalities are available around where you live.



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Tuesday, February 21, 2012

Diagnosing Respiratory Infection



The scenario might sound familiar: You take a couple laps around the arena with your horse, and suddenly he starts coughing so hard he yanks the reins out of your hands. You let him rest but he doesn't seem to be able to catch his breath. Could he have picked up a respiratory infection at the last horse show?

This is a typical case an equine veterinarian would encounter. The owner brings a horse in to a referral clinic, reports a cough and exercise intolerance, and might immediately ask for him to be put on antibiotics. As veterinarians, our job is to decide if antibiotics are necessary and beneficial, particularly since we're seeing increasing resistance of bacteria to these drugs. So how do we decide? And if it's not a bacterial infection, what else could it be?

Your horse's recent history is incredibly relevant to the diagnosis. Be prepared to answer a barrage of questions about new hay or bedding, turnout changes, any new horses in the barn, recent travel, vaccination status, appetite, what triggers the cough, whether it's dry or wet, or if there is any discharge, among other inquiries.

Your vet might then perform a physical exam on the horse, watching him breathe in the stall, undisturbed, taking note of his overall condition and demeanor (e.g., is he alert or dull?). Then once the horse is settled after the trailer ride to the clinic, the vet might perform a more in-depth respiratory exam, listening with a stethoscope for audible evidence of changes (such as increased fluid and scar tissue) in the lungs and/or trachea. More severe changes will be audible at rest, whereas subtle changes will only be detectable after exercise. Longeing for 5-10 minutes is usually sufficient to get the horse breathing deeply enough to hear the entire lung field.

An alternative to longeing is the rebreathing exam, during which the veterinarian places a plastic bag over both nostrils, causing the horse to inhale expired carbon dioxide instead of oxygen. This will stimulate the horse to take a deep breath once the bag is removed from the nose. The vet will listen for crackles, wheezes, or muffled lung sounds and determine whether the horse has difficulty breathing in or out. Often in a respiratory infection the bottom of the lung field sounds abnormal, as gravity pulls mucus and other fluids downward. Inhaling is also typically more pronounced. On the other hand, with recurrent airway obstruction (RAO, or heaves) the caudal (towards the tail) lung fields are abnormal. A horse with RAO has a harder time exhaling than inhaling due to scarring of terminal bronchioles (the tiniest airways of the lungs) and oversecretion of mucus. The extra fluid within the lungs can obstruct the smaller airways when they narrow during exhalation. Thus, increased abdominal effort is required to push the air out.

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Listening to the lungs might not provide enough information to determine if the pathology is infectious. Lab work (including a complete blood count and chemistry) or additional diagnostics might be required. The presence and degree of a fever can sometimes help determine if an infection is bacterial or viral. If the veterinarian suspects a bacterial infection, a transtracheal wash or bronchioalveolar lavage might be necessary to acquire a fluid sample from deep within the respiratory tract for culture and to determine the bacteria's sensitivity to antibiotics. Thoracic ultrasonography can help the vet identify pleural pneumonia (infection of the lung lining) as well as lung abscesses or masses.

If your veterinarian determines your horse has a bacterial infection, he or she might prescribe medications to be administered orally, intravenously, or intramuscularly. Viral infections are most often treated with supportive care and sufficient time off work. RAO is often treated with bronchodilators and corticosteroids, but rule out infection prior to treating a horse for RAO, as steroids can suppress the immune system and cause an infection to worsen.

While medication might be necessary, environmental changes and supportive care are often the cornerstone of respiratory condition treatment--whether viral or bacterial. Ensure your barn is well-ventilated and kept clean to reduce airborne allergens such as pollens, dust, and ammonia. Infectious or not, most respiratory diseases are preventable with good biosecurity measures, vaccination programs, and responsible farm management.